LN Engineering Ceramic IMS Bearing Failure at 30k miles

I had a local shop preemptively replace original IMS bearing with the LNE ceramic bearing in August 2013 at 54 kmi. They said that they had to do an inspection in which they cut open the oil filter and it was clean. The magnetic drain plug was clean (just microscopic fuzz) at each oil change until I changed the oil in January 2015 at 86 kmi, when there were lots of metal flakes up to about 0.8 mm long. I cut open the oil filter and saw the same thing. I drove a few hundred more miles and the drain plug had more flakes on it. Here are some of the flakes that I wiped off of my magnetic drain plug with a paper towel. The car ran fine and made no unusual noises. After getting conflicting advice from several mechanics, I stopped driving the car, had the motor removed, and sent it to MB Motorsports in Illinois for a rebuild. They disassembled it and found that the IMSB was wobbly (see video at https://docs.google.com/file/d/0Bwcd...lnUGJURkk/edit ). As you can see jn the photos below, the ceramic ***** are fine, but the inner and outer races have a lot of steel missing. This steel from the IMS bearing had gotten to the crankshaft and damaged its bearings. Apparently I caught it a while before complete engine failure, which would have cost more for the rebuilt as my core would have been almost worthless. Here's the bearing still in my old engine. The video shows how the shaft protruding out is wobbly. The IMS flange. On new bearings, the date code (G2 here) should match that on the shoulder bolt (H2 below). Mine from two years ago obviously don't. The dot-peened label from LNE on the shoulder bolt. After removal, the ball bearings and races are still held together. Disassembling the bearing. With the rubber removed, the ceramic ***** are visible. Disassembled. Nasty wear on the outer race. Ugly wear on the inner race. This appears to be the source of my metal flakes. The LNE IMSB cost about $3K to install. The rebuilt engine and installation is another $14K or so. I'm out $17K, when if I had done nothing, I would probably have been fine (statistically, I've read of an 8% failure rate for the 996.2s, and those are lightly driven, which is not my case). When I had the LNE IMSB installed two years ago, I thought it was a permanent, low-risk fix. I am particularly disappointed that at some point after that, LNE decided that this product, the IMS Retrofit, was not a permanent fix. They now say that if you love your car (which I really do) to install a different product, the IMS Solution. I called LN Engineering and they didn't have anything helpful to say. The technical guy I talked to said that the single-row bearing was a weak design (agreed) and that if it was going to go, it would have in the few thousand mile (no, it was fine for about 30 kmi). They did not record my name or any other information, so they are not taking statistics on this. Here are the four replacements for the stock IMSB I know of: * LNE IMS Retrofit, which has ceramic ball bearings. This was an interesting idea, but it turned out to be a bad one, because the harder ceramic bearings can wear the steel races. Heck, I use ceramics to sharpen my very hard steel knives. * Pressure-fed steel or ceramic ball bearings, which Pedro's Garage uses. This resolves the problem of lack of lubrication that the stock bearings had. I would be wary of the ceramic bearings. * LNE IMS Solution, which uses a pressure-fed plain bearing. This is a great idea, and it's not a new one: Porsche used in on intermediate shafts for 911s up through the 996s with the M96 engine. The 996 GT3 still used it. The biggest problem I have seen with this is finding a local installer. * German roller bearings, which MB Motorsports, Vertex, and other rebuilders use. Roller bearings can handle much higher loads than ball bearings because the force is distributed over a much larger area, resulting in a lower contact stress. I've heard it said that roller bearings are not good for side loads. I don't see an issue in this case because the other end of the intermediate shaft already has a plain bearing holding it in place. I've also heard that roller bearings cannot handle the engine speed. Take a look at a parts diagram for the transmission. It has roller bearings, and the input shaft is of course running at the same speed as the crankshaft. And the IMS runs at 2/3 of the crankshaft speed. ** One more product I have to comment on is the LNE IMS Guardian. This is a pair of electrical contacts integrated into their magnetic drain plug. When enough metal flakes pile up, the contacts are shorted together, closing an electrical circuit. This just tells you that your engine is generating ferromagnetic metal flakes, most likely from the IMSB. The problem is that by then it's too late to replace the IMSB. LNE's own rules require that there be no metal flakes in the oil before installing the IMS Retrofit or IMS Solution. This means that the owner is already screwed and needs an engine rebuild. The car can be driven a while longer before complete engine failure, or the driver can stop (like I did) before the engine dies at an inconvenient time and get a rebuild. This same concept is used in some aircraft internal-combustion engines, and it's clearly a good idea to land once there's metal in that engine oil. I just don't see it helping much in a car as long as a magnetic drain plug is used and inspected at each oil change. While figuring out what to do, I'd like to thank Jake Raby for his many e-mail responses to my questions. As a PhD engineer, I really respect and appreciate what he and LNE are doing: finding the M96/M97 failure modes and addressing them (which really was Porsche's job, but they dropped the ball on that one). In the end, shipping my car to Flat 6 for a few months or more (depending on their lead time) and spending $22K+ just wasn't possible for me right now, although I do believe that the result would be nearly bullet-proof. And I could have gone from 3.6 to 3.8 liters with new LNE Nickies cylinders for the same price. In the end, I found an X51 engine that was being rebuilt at MB Motorsports for $12K that I could get in a month or so (plus $2K local installation). I'd like to thank Agnes and Martin there for taking photos of my engine and the used bearing. I know Jake and MB are feuding, but both know what they are doing and offer great products at different price points and with different lead times.

I see something in your photos. Do you know what happened to your core engine? I desperately need some information from that engine. I've been on to something for a while.

I don't understand the H2 v. G2 date stamps and what that implies? I also don't understand the rubber seals since I thought the retrofit was splash lubricated. . . in the pictures on the LNE website it looks like the retrofit bearings don't have these seals. Was this a change in production, or just not in the photos on the LNE website?

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The number and letter designations are production run dates and batch identifications. All the LN bearings are if an open design, the seal is ONLY on the backside of the bearing to keep oil from filling the IMS tube with oil. I have noted the localized inner race wear that's seen here with many OEM bearings that were failing. I have finally found what leads to this, and it will forever change the qualification process for engines that will be retrofitted in the near future.

The IMS is somehow off centered causing the one-sided wear?

Would the IMS Solution have prevented this failure?

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In the first photo, the black seal is on the front side though. Um...

Yep.....

Don't want to jump to conclusions, but this smells fishy to me

1. Somebody put the old seal on a new bearing -- causing lack of lubrication leading to failure?; or 2. Something more sinister....

I believe it's legit per this thread https://rennlist.com/forums/996-forum/703228-lnengineering-replacement-ims-bearing.html The front side black piece is not a seal, more like a shield.

The OP posted the following on 6speed online, so maybe that could be a contributing factor to the failure: http://www.6speedonline.com/forums/9...ne-damage.html "I was rear-ended last year hard enough to knock the aftermarket stereo out of the dashboard. The external damage looked minor (see photos). It turned out that the internal "rails" that act as a frame were crushed inward an inch on the right and half an inch on the left. You can see that the right tailpipe extends more than the right one and that the rear panel has buckled a bit. It cost $12K to repair, which included removing and reinstalling the engine. About 30k miles ago I had the LN Engineering IMS bearing installed. I only use Mobil 1 0W-40 and change the oil and filter at 2/3 the interval that Porsche recommends. At each oil change there has just been a little fuzz on the magnetic drain plug. I just changed my oil last weekend for the first time since getting hit. This time my drain plug was completely coated with flakes of metal in the 0.4 to 0.8 mm size range. I cut open my filter and saw more of the same. Usually metal in a 996 engine is from the IMS bearing failing, but mine is now ceramic, so that shouldn't be it. Does anyone know how an accident might cause the metal flakes in the engine oil? Is there something like an engine dimension that I can measure to show that the accident caused engine damage. If it's from the accident, of course I'll have the other driver's insurance pay for it. I don't see coming up with $22K to have the engine rebuilt any time soon. "

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That looks like a cage to me, it doesn't extend out onto the seal groove in the outer race or inner race. The seal on the back side is marked RS1 which is the designation for single sided sealing.

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...aah, see you came to the same conclusion. I had not refreshed before replying to an older post.

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Thanks for confirming!

So, could the rear end accident have caused or contributed to the bearing failure or the fact that they "removed and reinstalled" his engine to repair the collision damage? Or, does Jake want to share what causes the bearing wear and why the qualification process will change for future retrofits?

The IMS housing bore is sometimes not centered other times the crankshaft is not centered. Both of these create a condition that is less than favorable for the IMS bearing. I noted certain constants when disassembling bearings that lead to the current developments. This is why some engines see multiple bearing failures; because the engine it's self is a leading contributor.

As with any reported failure, I am sorry to see that one of kits possibly was at fault, but being there was already a thread going on 986 Forum regarding this failure, I figured it was important to reference that thread and make a few clarifications. http://986forum.com/forums/general-d...g-failure.html The engine builder in question was banned from Rennlist and his motivations are questionable, as he's trying to use this failure to get his roller bearing kit into wholesale distribution by discrediting the work Jake and I have done. At no point was LN Engineering contacted to even discuss this - this went straight to the forums, again past posts by "Porsche-Land" again and again have been self-serving. We do not have all the information here to truthfully understand what happened. As with any mechanical system or component of that system, there will be failures, it's a matter of reducing the liklihood of said failure. Well knowing that the M96 engine has dozens of modes of failure which can cause foreign object debris that can in turn damage the rest of the engine, including the IMS Retrofit bearing, with a reported 30k miles on the bearing, it's likely there are external factors contributing to the excessive thrust loading indicated in the photos of our bearing. Again, as I have posted on other threads and as is posted on our website, there have been legit LN bearing failures which are far and few between- these occur almost immediately and we can substantiate that it's likely the bearing itself due to jobs being properly qualified and the health of the engine verified and determined as suitable for retrofitting. Warranty or not, if the procedure is carried out properly, we stand behind our product and will usually help out in some way to lessen the pain, even beyond the part warranty, again, if the job was carried out properly and if there is even the slightest chance that indeed it was our bearing.

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This is my understanding both from yourself and from other sources as to one of the major issues causing multiple failures.

Definitely a tough situation for everyone involved given that other factors (i.e., a third variable) can cause a meltdown. To Jake's point, one local Porsche shop owner told me that he had an owner/car that had 3 failures. Hope the car gets back on the road and the owner gets his money's worth on his new engine. The X51 is great.

Oh boy, here we go again. 20+ pages on the topic of the month predicted. To be fair to Martin, he really can't reply since he was banned, so topic should really be centered around the failure itself and not him or roller ball bearing, at least in this thread.

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Ok running with that, how does this issue affect any kind of retrofit or the solution if one has those conditions present in their engine?

Yes, that was my original question about whether the IMS Solution would have saved this motor? And, are you guys (Chuck/Jake) developing a tool or measuring device to tell if the bore or crankshaft are centered or within spec?

Subscribed If I read this correctly the issue is the crank or bore for the IMS isn't centered longitudinally in the block?

So is a ceramic bearing more or less susceptible to failure that a standard bearing is the bore is misaligned?, is one more tolerant than the other? General question on bearings to any engineering experts. I dont wish to be flamed, but I wonder how many actual failures are due to misalignment in which case replacing the bearing with a ceramic of any makebrand/seller makes no difference.

Its already developed. Awaiting the green light from the Patent Attorney before going further. There are several planes to be concerned with in regard to alignment and the tool I have developed takes all of these into consideration.

Porsche discovered the bore misalignment for RMS a long time ago (~9yrs) and they came up with the go no-go tool where a tech will use to decide whether to replace the RMS or the engine (under warranty). Those engines with misalignment will have the RMS failed repeatedly. So it's quite easy to imagine the same kind of misalignment can happen to IMS as well.

Guess what? Those engines with a misaligned RMS also have issues with IMS housing bore distance.

Can it be fixed by a precision custom made IMS flange with a slight off center offset to compensate for the misalignment?

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Each misalignment would be different so each flange would be different. Some crankcases are not correctable.

@Jake: My old engine is with your friends at MB Motorsports. @Charles: You said "At no point was LN Engineering contacted to even discuss this..." Actually, I called LNE in February after I had found metal in my oil and was trying to figure out what to do. As I mentioned in my initial post, I called again last week and the technical person didn't have anything helpful to say. I think you have some great products. I am using your magnetic drain plug and spin-on oil-filter adapter. I would be glad to have the IMS Solution and Nickies cylinders. However, the ceramic IMS bearing didn't work out for me in the worst possible way. Everyone: Please keep the posts useful to the 996 community. I have no intentions to flame anyone; I am just stating what I believe to be the facts. https://rennlist.com/forums/images/smilies/smile.gif Note that on the 986 forum there was a post where Agnes at MB said that they referred a potential customer to Jake for the IMS Solution rather than their roller bearing.

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I read the thread too and Martin also said that he too would use the Solution for his own personal car if he wanted a permanent solution. However all of this might be a moot point if what Jake is saying about everything being centered is true. I can see a future PPI being invasive and consisting of a center measurement as part of the process. Now there'll be a lot of retrofitted worry warts losing sleep once again. Lol.

My car had one of the engines that had had a problem with the bore. "Intermediate shaft bore out of round by 0.07mm" (from the technician's notes). The car had had a history of chronic RMS and IMS Flange leaks since it was built with the tranny out at least half a dozen times per the receipts. The real issue was finally discovered after the prior to me owner bought it and the car was going through its CPO checks. The engine was then swapped out with a reman'd one, no issues since (knock on wood). Oh, the notes also stated that the tech actually split the cases to measure it. He was directed to do so by the factory.

Ok, not an engineer nor engine expert...could the "misaligned crankcase bore" be the real smoking gun in the bearing failures? Or at least a contributing factor? Is this typically measured prior to installing a replacement from a failed bearing? Could this be why some cars run "forever" with no problem and some do not?

Until my tool development, there was no way to check this dimension.

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Not an engineer either but my car (the one that had the engine replaced due to the bore being off, two posts up) was at 58000 miles at the time, the only issues were leaks, there was no mention of the bearing being bad. Presumably it wasn't about to fail either (but who knows), so in any case it lasted a lot longer than some others. My car's symptoms were repeated leaks at the RMS and IMS flange after multiple replacement and updated parts.

so... wouldn't an "out of round bore" be a completely different issue than a "misaligned bore"?

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I'm not sure but someone can probably enlighten us. It may mean the same thing, I'm only transcribing what was written on my work order / receipt. But on the face of it, to me out of round generally means oblong - and misaligned generally means it is the correct size/shape but not placed in the correct position. But like I said it may mean the same thing in this case, unfortunately neither the tech nor the engine are available to ask. What matters to me is that the factory did the right thing and stepped up with a new engine without being asked to. I was pointing out my experience in order to mention another issue with some (or at least one) engines.

I am assuming Jake has been aware of this for some time. I am assuming the tool he has designed has been in his hands for awhile even though the patent has not been issued yet. I am assuming that if he found an off center bore he would not install a new bearing unless he could correct the problem or he would be setting himself up for a failure. Lots of assumptions, hopefully Jake will chime in.

What we are talking about here is the distance between the crankshaft (which drives the IMS) and the IMS housing bore (which holds the IMS flange, thus centering the IMS Bearing). This distance can be too great, not great enough, or perfect. The challenge has been to determine the perfect distance for the measurement; because its all empirical data, as the factory gave us no mention of any of this. When I saw the localized erosion of the inner race of the OP's retrofit bearing, it screamed that the instance was aggravated like many I have seen before that were in process failures of OEM IMSBs. A pre- qualification that we do here includes this measurement; but until I developed the tool others could not easily measure these distances and alignments. That said, even if they could, they would not know what was a good or bad value. As we learn more and more about this things get better and better. Meanwhile, the other guys sit around coming up with things we already had (years ago), and they are only concerned with sales. They tell you what you want to hear, and their hands stay clean.

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So I gather from what you have been posting on this thread that you suspect that the OP's engine had an IMS shaft that is out of tolerance leading to early bearing wear. It does make sense that a misaligned shaft's bearing would wear unevenly due to uneven application of forces. And such a theory would fit with the inconsistent nature of the IMS problems. IE, some engines have problems, often at relatively low miles, while other engines never have a problem. But, if misalignment or a tolerance problem caused the OP's LNE Retrofit bearing to fail, why did his original bearing last so long? The original bearing lasted longer than the LNE bearing and was showing no signs of failure when it was changed out.

A few things jump out at me here: 1) The OP has a very short posting history. 2) The failure has been diagnosed by Martin's shop who (while denying it) has made it obvious that he has a bone to pick with Jake. 3) Metal debris is found on the magnetic drain plug AND in the oil filter, but the OP decides it's fine to fill it back up and drive another few hundred miles? Seriously? Why the hell did you install that plug if you are going to ignore what it tells you? 4) No mention is made in the OP of an apparently significant accident in the same time frame, this is instead found by the RL Detective Corps. 5) An incendiary thread title that implies the LN bearing is at fault. I could be totally wrong, but this reads to me like another bad attempt to attack Jake and the LN products (the "I like LN products and respect Jake" comments read like the "I'm not a racist, but..." opening line).

I agree that the subject line is very suspect.., But when you are at the top of the food chain, you have a target on your back. We are used to that. That said, the point about the original bearing lasting is a good point IF the misalignment does exist. I have also considered this. We do now know if the OP registered his OE bearing with LN by sending it in, if he had we could look at the data base to see if it had any localized wear when it was disassembled and inspected. I merely noted the localized erosion of the inner race (the one that is stationary from the moment it is installed) and picked up on the issue as I have seen it play out before. Localized erosion is always aggravated by something. Why I do so much with this failure, is because it intrigues me. All the dynamics and variables that lead to issues are never ending.

"3) Metal debris is found on the magnetic drain plug AND in the oil filter, but the OP decides it's fine to fill it back up and drive another few hundred miles? Seriously? Why the hell did you install that plug if you are going to ignore what it tells you?" THIS....

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You have indeed turned what may have been intended as an ugly thread into an enlightening one, thanks as always. In your opinion, how long would it take for the misalignment damage that is shown to occur? Could it be that this rear-end collision caused something to happen internally and this damage occurred over the "hundreds of miles" that he ignored signs of a problem? Seems unlikely from my layman's point of view, but it could explain why the original lasted so long compared to the new one.

I've had a handful of bearing failure reports that happened after a vehicle has crashed... But there's no rhyme or reason with it. It's too far out for speculation too.. The studies continue. Maybe one day we'll be able to put the whole puzzle together.

As I knew it would happen in good ole RL fashion, let's get back to the original topic. Jake has made some observations that may or may not affect most of the engines. It is unknown at this point. His tool won't fix the issue but merely diagnose it. There will be a certain amount of pissed off owners that will be turned away when trying to get a retrofit done. The ones that don't get turned away by shops that either do not carry out the prequalification or does it but wants the extra business of installing IMS, could have a false sense of security and/or suffer the consequences later. When is that "later" is the million dollar question. If my doctor told me I could get a certain cancer when I'm 90yo wouldn't bother me as much as if he said 30 for example, Also do we know if other Porsche engines have always had some off center tolerance issues too?

Jake: I echo what gnat said above...Thank You for sharing your knowledge and experience. I have not read the "other guys" deal and don't plan to. There will always be professional jealousy but it is ashamed when it turns into attacks. I appreciate that you speak with facts and not emotion.

I would think that a misaligned IMSB would fail pretty quickly. Cars that are driven often and "like you stole it" should have failed faster than low mile garage queens. This goes against the conventional "wisdom" that is often mentioned around here. Jake...if the IMSB Retrofit is not a true 50k mile fix for some cars, is the IMS Solution, the solution?

Since we are doing the guessing game, the bearing flange could just as easily not be at a right angle to the block as the block bore being out of alignment. Someone needs to make some careful measurements of everything before coming to a conclusion. Until then we are all just guessing. However, the original bearing lasting longer than the replacement is an interesting point.

It definitely doesn't effect all engines, or even most of them. It is noted enough to warrant attention, and to create concern. I first noted this when developing the IMS Solution, and it made me chase my tail for a while before I figured it out. I had one of the test engines that created localized wear that was ever so slight on the flange, but none of the others had this. One late night I just happened to take not where it was occurring, and decided to break out the measurement tools. Thats when I found the issue. Every since then we've been watching for this and taking measurements during pre-qual. Trust me, they will be. I have had a guy ship me a car from Canada that failed the pre- qual inspection and we refused to do the work, because the car wasn't qualified. He was all sorts of pissy when I presented him with the data and explained it. That makes no sense, because in the end we saved him lots of money and we caught an issue that was repairable before the engine failed. What did he do? Called car max and told them to come pick his car up here, he basically threw it away. When we do any retrofit there's no chance of failure, because unlike any other shop, we can't simply blame the part for the failure. Here we have to know the case is a solid one and that the engine will not have any issues moving forward, no matter what. Thats how we've done over 400 retrofits and haven't ever had one fail. We take no chances, and moreover we know how to pre- qual the engine, because I developed that procedure and the associated tools. . The real issue is the techs. Other shops pay people on commission (we don't) and those people don't get paid if they don't produce. All too often the tech will pull the sump plate and find debris or other issues and they wont's anything, because thats their paycheck at the end of the week. Its not their shop and its not their product, so they don't care. They have nothing to lose, except money at the end of the week if they turn the engine down. Its easier to be a victim than a failure, so if the engine that was not pre- qualified ends up failing, the shop just says "sorry, not our problem". This is what happens today, and it comes more from the shops that have done A LOT of IMSR procedures as they have learned how to cut corners and do the job cheaper. Thats why you NEVER, EVER price shop for this procedure. If you do, you will get exactly what you pay for, plus a bonus that you won't like. If you have precision measuring devices and if you know how to use them well enough, you'll find a gripe with every engine that you measure. Just like when I crewed aircraft, I could down any aircraft on the flightily if my pre- flight was extensive enough. Some days it was better to be in the air than on the ground, so we had to look at the gripe and know if we were going to be at risk of falling out of the sky, or not. There were lots of those days. I got lucky. No matter what, it is.. I am totally biased on this, but of all my developments the invention, development and distribution of my IMS Solution is the one I am most proud of. The Solution is the most forgiving of debris laden oil, misalignment and collateral damages stemming from other issues. Removal of all the dynamic components is the key, each of those bring with it another wear point and another failure point.

I sent my car all the way from Las Vegas to Jakes shop within days of owning it. I read this site right AFTER I got the car. I was not looking to buy a Porsche of any kind but I took the car on trade towards another car I was selling. I knew absolutely nothing about its value or the issues that I soon discovered. I did not know anything really about the different model Porsche's but I always liked the way they looked and was under the impression that they had similar motors to a Volkswagon. I didn't drive my car until AFTER I took it on trade. I was planning on selling it as it only had 18000 miles on it and looked and smelled new. I knew the owner and remember when he bought the car brand new. I also knew he had some Ferrari's and other vehicles and that the Porsche would be just another garage queen that would get the best of care but would driven very little. In any case I liked the way it looked but after driving it I really liked it even more and I thought I should keep this car instead of selling it. After reading this site and still making the decision to keep it and to have the issues dealt with for peace of mind I decided to contact Flat Six. I liked Jakes attitude on all his posts, he seemed to be the expert and he didn't ***** foot around about anything, he had done much work and was in my book a fanatic. The perfect guy to send your car to if what you were looking for was the peace of mind that your car would be as good as it can be in todays world. The price would surely be higher but so would my peace of mind. I was told by Jake that he never had a failure, he didn't care how little miles were on my car it would still spend a day getting pre qualified and only if it passed that would he do the work. I've never been anything but happy that I sent the car there. Now I realize there is a guy in So Cal named Tony that Jake speaks highly of that also would have given me the peace of mind that I have now if he had done my car. I still am a firm believer that price should be the least of the criteria if a decision is made to do the IMSB, the main thing is to get the job done the best it can be because like we learn here there is lots more to this than a bearing swap.

Jake, out of your 400 installs to qualified engines, how many didn't pass your pre-qualification? Just curious.

+1 - I sleep a little better at night knowing that Tony Callas and his excellent mechanic (Ramon aka "Ray") at Callas Rennsport did my IMS Solution install. I played Russian roulette for about 1 year after my CPO warranty expired, and based on Jake's advice went with the Solution over the retrofit. The Solution is pricier but I did not want to worry about changing it out again (assuming I keep the car for a long time), or with the potential that some third variable would cause even a replacement bearing to fail. I've got about a week's worth of driving on the Solution at this point and all seems good (including 100 MPH on the bank at Festival of Speed AAA Fontana Race Track during the track tour), and my daily commute of 220 round trip. The Solution seems to make the engine rev a bit higher (e.g., 3200 to 3500 in 5th gear at 70 to 75 MPH) compared to before the install -- or this could just be my imagination. But I like it so far. Now, let's just hope the chain and rod bolts hold.

RE: The misalignment issue. I read through this thread and the one on 986 last night (I'm flaps10 over there). I'd like to add to the discussion if I may with regards to the misalignment issue. I'm unclear as to why slight variation in the distance between the centerlines of the crank and IMS would cause an issue, since there is a chain with a tensioner between them. Jake, you obviously have observed something there so I'll respectfully leave that to you. As far as angular differences between the centerlines, that is a discovery with some meat on it. When I first read it I thought, "okay, so we will end up welding up the bores of the crankcase and then align boring them to an agreed upon tolerance. Problem solved. However, it is way more complicated than the bores in the crank case. This is a situation that as a designer/machinist we refer to as "stack up". It is the collective imperfections of a pile of parts. If you have several parts to bolt together and they are machined to a tolerance of +/- .005" they would, in most cases, be considered pretty damn well machined. In fact if you want parts machined to +/- 0.005" day in and day out you should be prepared to pay some good money. (Not that 0.005" is anything like amazing, but please stick with my blathering for a bit.) If each of those parts were manufactured to the low end of the tolerance, then after 5 parts you are off 0.025" and that (could) cause a huge problem. In the old days we would have done a lot of machining of assemblies, or shimming. If you are cranking out a car every 120 seconds you don't have time for hand building anything. You need to design intelligently so that tolerance stack ups "wash out" every few parts, but I'm already getting off the track. This is my wheelhouse and I get a little excited. Onward... To help others visualize my input here, there are a pair of holes in the front and a pair in the back of the crank case. The top pair is for the crankshaft and the lower one is the IMS. But. Those bores don't center either of those shafts. Let's talk crankshaft first. The bores in the crankcase have the rear main seal in one end and the front main seal on the other. The seal is a wide gasket. To be sure, if there was significant misalignment it would cause early failure of the Rear Main Seal (RMS), but again, the crank isn't located by that bore. In my perspective an RMS failure is a zit and an IMS failure is *** cancer, so I'm not going to fret about RMS failures in this discussion. The crankshaft is located by the bearing carrier, which is dowel pinned into the bank 1 crank case. Right there is issue number 1. The bores in the crank case are done in one machining set up, and the locations for the dowel pins are done in another. Any time you take a part off of a machine and put it in another (or unclamp it and rotate it in the same machine) you introduce an opportunity for variation. Before anyone says "but it's done on a CNC!", my response if "pfft". All CNC does is allow you to make the same mistake over and over with shocking repeatability. And if you are running a $70k FADAL it just isn't the same as a $2 million Mazak or Okuma. It just ain't. Just one chip getting between your clamping surface and your part and you are off. One guy clamps the vise like this, and on second shift the guy does it like that. Journeyman machinist vs. button monkey. We can pretend that Porsche only hires Journeymen. Now add the bearing carrier itself. That is one beefy block of two kinds of metal. That carrier and the crank appear to me to be the only two things about the M96 that are "hell for stout". That carrier controls the crankshaft centerline, and it has a dowel pin pattern which matches the bank 1 locations. They pin together very nicely, or did in my case, but the dowel pin pattern can be machined very nicely "to itself", that is, the hole pattern is spot on, but if bank 1 crankcase half or the bearing carrier half was tipped just a tiny bit in the machine where those features were created then everything is going to look just fine. Let's go to the other shaft, the IMS. What a friggin train wreck. There is a bore on the flywheel end where the famous IMSB lives. It is a bore that is on the centerline split of the crankcase. Not exactly ideal right from the get go. If the case halves aren't "married" and machined as a pair then you run the risk of the bore not being round (picture a football for the exaggerated view), or one perfect half circle could be shifted vertically, resulting in a mismatch. To allow for this the hole has to be oversize. Just a touch, but it is yet another place for error. We aren't done with that end yet, because we need to add the IMS cover itself. The outside diameter that goes in the crankcase bore has to be undersize or it won't go in the hole. Granted, it is a pretty snug fit, but the IMS cover is held with three bolts. In my years as a tool designer I would use press fit dowel pins to locate two parts as perfectly as my machining processes would allow. Bolts are only used to clamp the parts together. Now lets look at the other end. Wow. Just wow. The oil pump end of the IMS, you know the one that doesn't cause any problems? It doesn't run directly in the crankcase bore either. It runs in the oil pump housing. The oil pump housing is a die cast contraption about the size of your face, maybe bigger. It has a "spud" on it that goes into that bore in the crankcase. It has a gap between its outer diameter and the bore in the crankcase that is big enough that there are two O-rings used. There is nothing precision located about the oil pump housing. It is held to the front of the engine (986, rear for you backwards guys) with an array of, what are they M5 bolts? Oh and one M10. Add to that, the chain tensioner for the non flywheel end of the engine spends its entire life trying to pull the nose of that shaft to one side. The holes in the oil pump housing are a class III fit, that is pretty damn sloppy so that it always fits together. But wait, there's more! This is where they chose to bolt on the front engine mount. In fact one of the four front engine mount bolts goes directly into the oil pump housing. I don't know what they were smoking when they came up with that idea but they probably had to go to Denmark to get it. There needs to be an added machining process where the oil pump housing and crank case half are modified so they can be pinned together with precision. I'm leaving that laying on the table right now. My point of all this is that it would be nice to say we could measure the bores of a crankcase and accept or reject it based on what we find. But the only way to get meaningful measurements during and engine build would be the assembly consisting of: Bank1 crankcase half The bearing carrier, with main bearings and crank installed Enough clamping force to hold the bearing carrier socked into place, just like we do for installing pistons 1-3 IMSB cover installed Oil pump housing installed IMS shaft installed Now you have a fighting chance to measure the angularity between the axis of the two.

Just a thought, don't want to start anything but wondering if anyone else is thinking the same thing - flame suit on. Fact. Most bearings don't fail. What if the problem is a misalignment and not the bearing. And you only replace good bearings on cars with out any misalignment issues or signs of failure. Then, chances are the new bearing (whether is be single, double, roller, pelican, etc.) will last because the first would not have failed. Therefore, a lot of people have replaced perfectly good bearings for no reason. And the failure rate for the replacement bearing will be really low. And lots of money spent on an unneeded repair. I wonder if Porsche has the answer or whether they don't really care.

Good question. Probably multiple causes of bearing failure, including the faulty seals allowing grease to be washed out, the load on the single row, and who knows what else. If it were misalignment only, then why would the 1999 failure rates be so much lower than the 2001 to 2004 (according the the class action settlement statistics 1% for dual row, 8% for single row as of the date of discovery/settlement) -- unless the 1999 MY had a different manufacturing process for the alignment issues.... Think it is multi-factorial and given that even some high mileage cars are now experiencing bearing failure I personally would still buy the relatively cheap insurance of a retrofit rather than a $12 to $20k engine replacement. Also since Porsche got rid of the IMS bearing in 2009+ after repeated attempts at fixing the issue -- my guess is they really don't know. Since our cars are out of warranty, they also really don't care. A few disgruntled 996 owners can be brushed aside since sales of the new models are still going strong.

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Hey Gnat: So does that make anything that I said untrue? I have previously been posting on 6speedonline. Because rennlist concentrates on Porsches, I moved here. I talked to several mechanics. Two, including one who is well-known for his development work on Porsche engines, suggested running another few hundred miles to see if the problem went away. I saw little downside: if the engine needed a rebuild, it would still need a rebuild, at the risk of the core being worth less. The upside was that if there was no more metal, the engine was probably fine. Gnat, you seem really smart. Tell me how this logic is wrong. No one could give me a reason that getting rear-ended would cause metal in the oil. In an email from Jake in February, he said that he'd heard of it, but I never got any details. I really wanted the damage to be from the accident, because then the other driver's insurance would pay for a new engine. After my local shop, who removed the engine, and MB, who rebuilt it, looked at it and found nothing linking it to the accident, I dropped the reference. Good job to the detectives on using Google! Yes, I think that the LNE IMSB is at fault. The races are clearly worn and I'm out over $14K. Sorry Gnat if the truth is incendiary. Yes, you are totally wrong. I asked posters to keep this discussion useful. I guess you're not on board with that.

DrMeMs: How long after the accident did the metal shavings start to show up? In the law, there is a concept called "res ipsa loquitor" meaning the thing speaks for itself. If your car was working fine and then an impact occurs and shortly thereafter things aren't working fine anymore -- one can impute the damage to the impact. I'm no expert when it comes to how these cars are put together, but a hard impact that causes some type of frame damage could damage other vital components from the impact itself -- and your shop and Martin may not have seen any "visual link," to the accident, but what if the impact caused the IMS or stud to wobble or come loose, causing the bearing to go south? (again I'm a lay person -- so maybe this can't happen). Again, it's hard to understand why your bearing failed if other LN bearings are in service and have not failed. Very hard to quantify since there are many unknowns (such as how many LN bearings are in service and how many miles do they have on those bearings etc.). You may want to speak with an attorney to see if you have a claim against the driver's insurance. I also hope you filed a claim against the driver's insurance for diminished value relating to the impact/accident. This could give you another $5 to 12K in funds from the accident, since an accident damaged 911 (even if perfectly repaired) is harder to sell and will bring less upon resale. PM me if you need additional information.

I saw the metal in my oil at my next oil change, about 4 kmi after getting rear-ended. My first thought was that it was related to the accident, but now I have nothing that proves it. I do feel that I am owed for the diminished resale value of my car. However, the OD's insurance company is with Southern California Automobile Association. Their agent just stonewalled me for several weeks after the accident, so I ended up going through my own insurance company under my collision insurance and paying the deductible, which I finally got back many months later. It's really easy for an insurance company to just do nothing. Any ideas for extracting the diminished value from them?

Yes. PM will be sent.

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I didn't call you a liar or question any specific claim you made. I pointed out a series of items about your posts that make the whole thing questionable. Based on my observations your post reads like a troll or mouthpiece for Martin. I haven't called you such because I'm not convinced that's the case, but that's what those flag would seem to indicate. That may be, but on RL you made one post about a roof rack and then a series of posts in a couple of threads implying that the LN bearing failed including starting a thread about it. For a "new" user to post such incendiary statements is worth questioning. That the basis of the failure statement is coming from someone who has personal and financial reasons to want to see Jake and LN smeared is also a red flag. The reality is that the odds are against the LN bearing being the primary failure point. It's always possible of course, but it is such a small chance. The much more likely scenario, which Jake has been kind enough to delve into, is that there were other issues at play and the bearing was a casualty of the motor not being healthy. This is why "LN Engineering Ceramic IMS Bearing Failure at 30k miles" is so incendiary without further evidence by a knowledgable non-biased party. It's well known that ferrous metal in the oil at the level you describe in the M96 is a sign of a very unhealthy motor. Anyone that is not seeing possible dollar signs and has a remote idea about these motors knows that continuing to run it is a bad idea. It's the simple difference between possibly being able to save the motor if it was indeed caught soon enough and a hunk of useless metal. The whole point of the magnetic drain plug is to know that something very bad is starting to happen. The wisdom is that you stop driving it immediately and get it throughly inspected. You are of course free to use it as a "my engine is going to die, so fsck it!" indicator though, but that diminishes your right/credibility to jump on a public forum and start moaning about how someone's product trashed your engine. Honestly (as evidenced in my dialog with Jake) I wouldn't expect an accident that didn't cause exterior damage to have an internal impact. When you are delving into a complex failure like this, however, something like a major accident in the recent past could be relevant. I debug problems for a living and the reality is that no matter how insignificant, all data that can be gathered is significant. Either to diagnose the given failure or to help build a predictive model for future failures. You are still jumping from A to Z and skipping everything in between. No one is claiming that those images show a perfectly healthy IMSB. The question is what caused it to get that way and why (if Jake's theory is correct) was the original bearing not similarly impacted (maybe that's where the accident comes in)? You are making up a cause to explain the result you see, but such things are rarely that simple. I am perfectly on board with that. I am also on board with making sure, given the history of IMSB related discussions on RL, that such claims are vetted and viewed clearly. It is also perfectly useful to make sure others that read this thread know that you never run the motor when you know it is throwing metal around in the oil. You lost your engine and I feel for you on that. Everyone holds some amount of fear that theirs can go (though we all accept and manage it differently), so we understand your pain and loss. What I have a problem with is how you presented the whole thing and your continued insistence that the bearing itself is to blame when you have no actual evidence of what happened (at least partly because you continued to drive it after the metal showed up).

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How long has this tool been in development?

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I don't think res ipsa loquitur applies in this instance. > duty > breach of duty > causation - Actual cause - Proximate cause > damages Even if you could somehow prove that the engine damage can be traced to the collision, there will always be the issue of defective parts, how the car was treated prior to the accident, etc. etc. If I were on the defense, I would have a lot of fun with a case like this. Traffic cases are fun. And they almost always settle, in my experience, because of issues of proof.

Yeah, for every argument there is a counter-argument and an insurance defense lawyer to raise those arguments. In positioning the claim: 1. My car went 58,000 miles on an original OEM bearing; 2. My car then went 30,000 on a state of the art ceramic bearing with improved design; 3. My car was rear ended and I suffered frame damage etc. 4. The next time I changed my engine oil I noticed metal that wasn't there in my prior oil changes during the past 30,000 miles with this bearing; 5. The bearing designer states that the likelihood of the new bearing failing in 30000 miles is minimal after X,000 installations. and so on and so on...Res Ipsa Loquitor every juror knows that a hard impact can cause unseen damage right? I'm still suffering from neck and back pain from a rear ender that totaled my car in college -- but nothing on the x-ray will show soft tissue damage. The diminished value claim also may take away the need to get into the engine damage and causation issues anyway and pay for all or part of the OPs engine repair cost, but a suit likely will need to be filed to get AAA's attention. This is not legal advice and one should retain and consult their own attorney. I'm not a litigator, I only play one on TV.

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Good point! I'm sure Jake and LN are keeping their ears close to the ground wrt future failure(s) within the same batch as this failed bearing. My point being that the inner and outre races of this failed bearing could be stemming from a bad batch for some reason(s). Moreover, this discussion has been all about single-row bearings, understandably. Wondering if sporting a dual-row diminishes the effect of this potential misalignment! Excellent read nonetheless and good luck to the OP.

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That's why I'm here. I have a 99 with a dual row and on third bearing (long story) and wondering if 75K is too long a service interval.

I'm not an engineer, or a lawyer, but one cannot exclude the possibility or, indeed probability, of some driveline side loading after an admitted accident including frame damage. Is it so hard to believe that the thrust vector of the driveline may not be centered post accident? And isn't it possible that the lateral shift ( if present ) would manifest itself in the driveline and its components/ bearings? From a laymans' perspective, the accident may be a contributing factor in this failure.

Exactly. and this too: http://www.bodyshopbusiness.com/powe...onsiderations/ or: RES IPSA LOQUITOR

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Not for nothing, but my 99 is on it's original with 120k.....

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The fact that we have to take all those steps before we arrive to the potential cause of injury (metal shavings in the oil that led to the engine being damaged) makes it so res ipsa would not apply, because it can reasonably shown that the injury could have occurred as a result of one or two more causes. OP stated he changes his oil at 2/3rds the recommended interval by Porsche. The bearing could have been defective. The IMS and crank bores could be defective. So on and so forth. So how much per hour would Mr. Raby or Mr. Navarro charge as expert witnesses? "The thing speaks for itself" ... If I didn't get it in law school, I didn't get it on the bar exam, but I'm slowly starting to figure things like this out. I should ask one of my colleagues who handles aviation injury cases about the doctrine of res ipsa . If only for the fact that she just picked up a new Maserati GranCabrio and she wears her skirts a little too tight and her heels are a little too tall.

Respectfully disagree. 1. Duty - to not rear end me while I'm sitting in traffic and use reasonable care 2. Breach - you rear ended me you *&%$ 3. Proximate cause - my engine worked fine until you rear ended me and then I discovered hidden damage that only became visible after I changed my oil since the part is hidden in the engine. And, so the presumption applies, and you can now rebut it if you, the defendant, can prove that the other 3 "causes" above are true. I already have 1 lay juror on my side - TSMacNeil Cal Evid Code: (c) If the evidence, or facts otherwise established, would support a res ipsa loquitur presumption and the defendant has introduced evidence which would support a finding that he was not negligent or that any negligence on his part was not a proximate cause of the occurrence, the court may, and upon request shall, instruct the jury to the effect that: (1) If the facts which would give rise to res ipsa loquitur presumption are found or otherwise established, the jury may draw the inference from such facts that a proximate cause of the occurrence was some negligent conduct on the part of the defendant; and (2) The jury shall not find that a proximate cause of the occurrence was some negligent conduct on the part of the defendant unless the jury believes, after weighing all the evidence in the case and drawing such inferences therefrom as the jury believes are warranted, that it is more probable than not that the occurrence was caused by some negligent conduct on the part of the defendant.

I'm gonna go against the grain and say DrMems is the victim here, not a criminal, although you couldn't really tell from some of these posts. He stated what he believes to be accurate. One can accept it or not but it's not gonna change what happened but it is at least a record of it. In the end he liked his 996 enough to keep it, even after an accident. He got a great deal on a x51 engine(for a great price) which I would consider an "upgrade" instead of just a "repair". Plus it seems like he got the OEM PSE mufflers with that which is also another great "upgrade". He's a true devoted enthusiast which I can't say for a lot of recent peeps on here lately. "OMG, my car is leaking fluids. I think I need to sell it NOW!!!!" If he drives it for 5 years trouble free, the last laugh will be on you guys. My $.02

How many of you guys actually fix your engines with your own hads? If you would, all these BS theories of a reared causing the bearing to fail would not be posted. These cars don't have frames, the entire drivetrain is suspended in rubber so even if the chasis moved, the engine and transmission will move with it. And if it didn't, parts would bend or break. Some of you guys have one heck of an imagination and zero first hand experience.

So, in a unibody car with the entire engine/transmission shifted a few degrees off-center would have no affect whatsoever? Makes no sense at all. I think most of us know there's no "frame" in the car. Grab a bicycle and shift the rear axle a few degrees out of true for awhile...report the results after a few weeks of riding.

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Actually, I had to pay for the PSE separately. I also had to purchase several other components for the X51 conversion, such as the intake and exhaust manifolds. I spent several hours documenting the differences at https://rennlist.com/forums/996-foru...mentation.html .

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A bicycle has a frame. Let the sprocket represent an engine since it is the power side. The frame holds the sprocket parallel with itself but the wheel is no longer parallel with the frame because you shifted only it. The chain which is like a drive shaft is trying to ben and its destroying itself and both sprockets. The Porsche has no frame or driveshaft and so the engine and rear axle shift together but they both are still inline with each other. After weeks of driving with this situation I just picture worn out tires since they are the only things not in line with each other any more. After reading the machinists post about how the engines are made I'm pretty sure NOTHING is inline anymore anyway. I wish Jake would respond to all he posted.

Yes, vivid imagination and admittedly no experience as an auto builder or mechanic. But, let me surround your head in rubber and drive a car into it and see if you have brain damage after the accident. Or maybe a better example, buildings in Japan that are built to withstand earthquakes -- building may stand but the contents certainly have shifted. [e.g., "Video filmed during the aftershocks that hit Tokyo on Friday shows high-rises doing exactly that - wavering dramatically without snapping. "You will get shelves tipping over and copy machines running across the floor, " said van de Lindt, but structural damage will be minimal, even when the top of the building lurches 10 feet or more in each direction. "It's like a yardstick when you bend it - it snaps back without any damage." Hollow walls hiding sliding metal plates are also common in recently built mid- and high-rise buildings in Japan. The heavy plates help dissipate motion." [Source: Washington Post article c 2011] But, you have a point. (and by the way -- I've changed my motor mounts and had my transmission mount replaced by the dealer -- and guess what, there is metal there too, not just rubber, so there are only so many degrees of freedom to move).

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My only complaint is how he is presenting the whole thing and putting all the blame on the bearing. It is entirely possible that there was a flaw with that bearing and it was indeed at fault. I really do believe that is a possibility. I also believe, however, that it is a statistically unlikely explanation AND a trustworthy diagnoses was not done at the time damage was first apparent. I do have massive respect for him that he put a "new" motor back in it. Most would say that was a dumb move and he'll never see that money back, but he is now in a select few that do more than talk about how special these cars are and that they are more than the sum of their parts. I hope ours never rolls craps, but if it does I hope I'll have the stomach to bring it back to life too (I'm not that attached to it, but she is which means so am I ).

I get my vivid imagination from articles like these, which admittedly may (due to differences in driveline etc.) have no application to the 996, but it is food for thought and should be vetted since no one apparently really knows why the bearing failed in this instance: "Rear-Ended Rear-end collisions often cause some displacement in differential mounting or support fixtures. On rear-wheel-drive vehicles with independent rear suspensions with half shafts, damage can be similar to that found on front-wheel-drive systems. In a collision, rubber support mounts and torque arms are sometimes relocated and under tension thanks to twisted or out-of-position mounts at either end. These mounts should be free moving and allow for pivoting at the mounting point. Any tension will create unequal torque, which will impart a thrust or sideload into the drive line, causing a lead or pull. Rapid wear of parts and noise can also accompany this type of problem. To fix this, it’s necessary to reposition or replace the damaged mounts. Other common problems mentioned by techs included crushed driveshafts on rear-wheel-drive vehicles and broken or twisted leaf spring mounts, shackles or hangers. Problems with side set or axle skew will sometimes require replacement of the vehicle’s differential housing. Burgant suggests that shops always look carefully at the drive-line angle, both at the differential and at the transmission or transfer case. Drive away or "launch" vibration is also very common following a rear-end collision, says Burgant. This may occur when the rear differential moves too far out of position when the vehicle torque is first applied and may be due to improper drive-line angle or defective springs or torque arm mounts. Solving Manual-Transmission Problems When I spoke with a few techs about internal damage to manual gear boxes, most agreed that clutch pressure plates can frequently be damaged on stationary vehicles hit from the front or rear. Finding and repairing such damage is important. One tech said a recently repaired vehicle was returned to his shop suffering from clutch failure. The diaphragm-type clutch pressure plate showed unequal finger position and definite signs of uneven contact with the throwout bearing due to misalignment. Cracked or broken gears and damaged synchronizers are often the direct result of a collision. Many techs I spoke with said such problems often won’t manifest for months or thousands of miles after the repair, so it’s important to check for damage while the vehicle is in the shop. "When repairing one of these hard hits, a good mechanical inspection is necessary," says Burroughs. "Insurance companies should be made aware of high-risk items that might be problem areas down the road if they’re not replaced at the time the structure and refinish work is completed.""

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I would say it's still a good value considering the alternatives. Some people spend the same as you and only get a base stock motor repair/rebuild for the same price. I'd say you did ok considering the circumstances.

And now no one will know if the debris was created by something else failing first... Or if the impact aggravated the issue... Or if it was an engine with misalignment issues. And the more importantly, what about that core engine?? What if it has a misalignment issue and is reused for another "new engine" and the issue is not addressed? That's why I always build the customers engine, we know what we have to work with.

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Stop typing dude, you are embarrassing yourself.

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No, Nothing to be embarrassed about by asking questions. I believe Paul Simon summed it up best - There must be 50 ways to kill your bearing.

Slip out the back jack, Make a new plan stan

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But you didn't ask a question, you've posted a theory that’s based on earthquakes and shelves moving in high rise buildings. This is a technical forum, not a courtroom where stupidity like this is OK. Trust me on this, it's embarrassing what you wrote. Might as well say the bearing failed because of the gravitational pull of the black hole in the centre of the Milky Way.

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You should see what Forcible Entry and Detainer Court is like in Cook County.

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Crap, so now I have something else to worry about. Will lead shielding around my car help prevent this?

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Actually you are incorrect on several levels. This is an enthusiast forum. Your posts don't have much technical data supporting your points. You are an expert because why? You can put together your car? You have a degree in Physics or Engineering and are an expert in collision damage? By submitting a hypothesis it opens up debate. The purpose of which is to potentially help the OP recover money from the person's insurance to help with his loss. The read between the lines questions on the article is why can this type of damage to clutches, differentials happen from a rear end accident, but not damage an IMS bearing. Sorry if that wasn't clear. Most of your post is fallacious argument with ad hominem attacks and an appeal to your claimed expertise due your wrenching skills, oh yeah and a reductio ad absurdum to boot with your Milky Way comment.

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Very funny. I like that one. Here's one for you two www.theflatearthsociety.org Cheers

This thread's topic has drifted. I really wish that I could show that my IMSB failed due to being rear-ended so that insurance would pay for it, but that is just wishful thinking. To allow pulling the body straight, my engine was removed and reinstalled by my local mechanic. He didn't notice any engine damage, and he obviously knew the car had been hit. Next, the mechanic in Campbell, California, who has taken Jake's class and was recommended by Jake, removed the engine for shipping. He was specifically looking for accident damage and did not see any. Finally, the experienced engine rebuilder in Illinois, MB Motorsports, also looked for accident damage and did not see any.

Yes. And that brings us back full circle. Very sorry this happened and you are out of pocket.

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WTF did you write in the last paragraph?!?! Sweet baby Jeebus! You are an expert at arguing but most of it is BS because you don't have the faintest idea what the F you are talking about. Trust me on this. You are wrong, this is a technical forum and this is a technical thread. There are lawyers here that actually do their own wrenching and know what they are talking about......you are not one of them. Trust me on this. . Yes, I'm an expert not because I can put my car back together BUT because I can take it apart and do it over and over and over again, like I have been for the better part of 30 years. BUT I also do have an engineering degree of sort too and been to courts as an expert witness. So......instead of arguing about earthquakes and rearends, why not grab a wrench and start taking your lawnmower apart for starters? You might learn a thing or two on a subject that you know nothing of. Peace out Cousin Vinny!

"oh yeah and a reductio ad absurdum to boot with your Milky Way comment." Sorry, but ^that^ sounds like it's right out of Harry Potter script...

Yeah, that does sound like Harry Potter, so I'll use the more common phrase of "slippery slope." Here ya go IMO - this will help you through the large words in the last paragraph: http://en.wikipedia.org/wiki/List_of_fallacies "Argumentum ad hominem – the evasion of the actual topic by directing an attack at your opponent." "False authority (single authority) – using an expert of dubious credentials or using only one opinion to sell a product or idea. Related to the appeal to authority fallacy." [i.e., I can turn a wrench, so that makes me a PhD Engineer and I can pontificate on physics, material sciences and parts failure). "In logic and critical thinking, a slippery slope is a logical device, but it is usually known under its fallacious form, in which a person asserts that some event must inevitably follow from another without any rational argument or demonstrable mechanism for the inevitability of the event in question." I actually am learning to do work on my car and have done a number of things. Won't ever make me a mechanic, but the point is you are wrong again sir. [Let's see, I change my oil, I change my wheels/tires, I change spark plugs, I installed the 997 shift console, I installed my new speakers, I installed a new oil pan when mine cracked, I own several wrenches, and torque wrenches and other tools -- doesn't mean I'll ever take out my engine and replace my IMS bearing]. Keep attacking, keep name calling cause it really shows your true colors. While your at it go take a basic course in physics, with particular emphasis on impact, force, and shock damage. You might then understand the arguments above. Here is a link for you when you where maybe you can read about impact forces and parts failure: http://www.winningwithemail.com/cont...ges/TP0445.PDF You sound like you are going Brian Williams on us now mr. expert witness that sort of has an engineering degree. What degree were you awarded and from what institution?

Here is the Wikipedia version for you IMO. Is this technical enough for you, or are you Sweet Baby Jeebused again? Shock: A mechanical or physical shock is a sudden positive or negative acceleration caused, for example, by impact, drop, kick, earthquake, or explosion. Shock is a transient physical excitation. Shock is a term for extreme forces that matter is subjected to. Shock is a vector that has units of an acceleration (rate of change of velocity). The unit g (or g) represents multiples of the acceleration of gravity and is conventionally used. A shock pulse can be characterised by its peak acceleration, the duration, and the shape of the shock pulse (half sine, triangular, trapezoidal, etc.). The Shock response spectrum is a method for further evaluating a mechanical shock.[1] Mechanical shock has the potential for damaging an item (e.g., an entire light bulb) or an element of the item (e.g. a filament in an Incandescent light bulb): A brittle or fragile item can fracture. For example, two crystal wine glasses may shatter when impacted against each other. A shear pin in an engine is designed to fracture with a specific magnitude of shock. Note that a soft ductile material may sometimes exhibit brittle failure during shock due to time-temperature superposition. A ductile item can be bent by a shock. For example, a copper pitcher may bend when dropped on the floor. Some items may appear to be not damaged by a single shock but will experience fatigue failure with numerous repeated low-level shocks. A shock may result in only minor damage which may not be critical for use. However, cumulative minor damage from several shocks will eventually result in the item being unusable. A shock may not produce immediate apparent damage but might cause the service life of the product to be shortened: the reliability is reduced. A shock may cause an item to become out of adjustment. For example, when a precision scientific instrument is subjected to a moderate shock, good metrology practice may be to have it recalibrated before further use. Some materials such as primary high explosives may detonate with mechanical shock or impact. When glass bottles of liquid are dropped or subjected to shock, the water hammer effect may cause hydrodynamic glass breakage.[18] Go ahead, now, discuss the technical points using math, physics and engineering.

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OK, I win:

SDS, dude.....just let it go man. No one is getting anything from your esoteric points and your defensiveness is getting really old. DrMEMS, do you have any specific thoughts about what caused the LNE bearing to wear so quickly? Do you think it has something to do with an improper installation, debris in the engine from some component failing, poor materials or workmanship of the LNE bearing, something else?

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No, I really can't think of anything for sure. It was perfectly fine for a few oil changes. I always kept the oil topped up--I check it every time I turn the key before starting the engine. I've never been on the track. I do a few autocrosses every year, which is blast. Porsches are supposed to be able handle this. I've never lost oil pressure. If I did, I would have heard a beep and had a red light on the dash, which I know because I had an intermittent oil-pressure sensor failure until I replaced it. I don't think it's crooked installation, as I would expect wear to occur right away. Maybe the fit of the ceramic ***** in the races was a little tight or loose so that the ***** did some rubbing in addition to the intended rolling. Or maybe the splash lubrication was not as good as it needed to be. Maybe if we hear of some other failures we'll see a trend. If anyone else has the same LNE failure, please document the batch number(s) stamped on the bearings, as seen in my original post.

While I quit caring about this story a few days ago, I get sds' indignation. This Imo guy has resorted to personal insults that reduce this forum to the level of oh- so- many Japanese boards. Disagreeing is one thing, getting personal and insulting is juvenile and ought to be beneath a Porsche forum. I guess it's not. Did the OP ever say if this LN bearing was installed by a certified installer? Seems Germaine to the mystery. The question the OP just asked ( other LN ceramic failures in similar fashion ) is the other Germaine question. I'd like to know as I, like many of you, have the LN product in my car...but this "technical pissing match" over causality is not getting us anywhere without more facts. Toodles

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My local shop that installed the LNE IMSB is not a certified installer. They said that they had experience and had recently done the job on several other Porsches (we have a lot of P-Cars here in Silicon Valley). I trust them.

I'm sorry but SDS is posting theories that are complete nonsense. He keeps insisting that he is in the right, poor guy has no idea how idiotic those theories are even if he can dig stuff on from Wikipedia. He is embarrassing himself by "sticking to it" and I'm embarrassing myself not being able to not to respond to it.

I'm stepping in.......I think the bearing failure is a result of another cause. I think it was installed out of alignment. Look at the threaded stem the nut goes on....do you see how distorted the end of the stem is? Was it whacked into place? I also think the rear collision shook a bunch of debris loose......stepping out with food for thought.

An interesting bearing issue has been lost.Lets get back to fixes ? Whatever the cause of this bearing failure - would any particular bearing type have survived better than the single row deep groove ,ceramic hybrid shown in the photographs ? Martin speculates that a cylindrical roller bearing is the solution without having identified the cause of the problem. Unless we know the cause of the failure ,how can anyone recommend a specific bearing type ? The misalignment issue is new(for me and many others it seems) in the IMSB saga . The theoretical solution is a spherical bearing ,not a roller,not a deep groove ball. A plain,spherical bearing, or a ball-type spherical bearing maybe -like a CV joint . Why measure for misalignment ? Just fit a spherical bearing !Ducking for cover !

I have plans to retrofit a U-joint on my intermediate shaft, plus for good measure, I'm going to install an 8" Kingsbury thrust bearing.

If misalignment exists anything that's installed into the engine will operate in less than optimum conditions. If it's misaligned, then nothing will be anything more than a band aid that sooner or later will be compromised. This misalignment issue is not new.

"The misalignment issue is new to the IMSB saga . The theoretical solution is a spherical bearing ,not a roller,not a deep groove ball. A plain,spherical bearing" I don't think "the misalignment issue" is new at all - it's just that Jake Raby only recently identified it as such (I think it's safe to say he's known about it for a while). As for "the theoretical solution" of the spherical bearing, I think Jake would take issue with that description as he recently received a patent for such a bearing. Just coincidently it's called "The Solution"

Nope, I just started talking about it.

"Nope, I just started talking about it." That's exactly what I meant when I said "I don't think "the misalignment issue" is new at all - it's just that Jake Raby only recently identified it as such (I think it's safe to say he's known about it for a while)"

I just ran across notes from my mechanic while the old engine was still in the car. He read out the camshaft deviation at 1.69 degrees on bank 1 and 0.88 degree on bank 2, which are well within Porsche's spec of 6 degrees. He said that this meant that the IMS bearing was not installed crooked; it it were, the deviations would be a lot worse.

Which leaves a manufacturing defect (like adverse cumulative tolerances) as the potential cause of shaft or bearing misalignment ? If this is correct, changing to a roller bearing will not be a long term solution. Spherical bearing maybe?

I propose an immediate adoption of Michell/Kingsbury fluid bearing retrofits. In addition to the bearing itself, it will be necessary to tow a compressor/gas generator to supply the necessary air pressure and volume, but otherwise this is foolproof. Note that some modification to PCV will be required to discharge the extra few hundred CFM of high-pressure air. Probably the motorsport AOS will work.

lol I'm beginning to come around and see some of the logic in Jakes' thinking. I had no idea the engine cases could be machined with such inaccuracies. Hard to believe, but if true, explains so much about the unpredictability of these failures. Still subscribed - begs the question: can this machined misalignment be corrected? That is my next question. regarding "shock" and its' effects, while I may struggle translating it to a vehicular accident, this is where I live: Picture of Supersonic Shock Wave.flv - YouTube

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Incorrect. The cam deviations have nothing to do with a misaligned IMS and cannot be used to diagnose such a condition. It takes considerable IMSB wear to show up as a cam deviation as well, and even then it will ONLY impact bank 1, as the end of the IMS thats supported by the IMSB only drives bank 1. I typically find cam deviations that are measurable well into Stage 3 IMSB failure; but, not before. I do not agree with his statement, or theory at all. The misalignment will not show cam deviations, because it is both very slight and also because the cam timing procedure and hydraulic chain tensioner will mask this. The only way to find this slight misalignment (measured in thousandths of an inch") is by using a precision device that measures three different dimensions simultaneously giving an actual value. A slight misalignment is HUGE to the IMSB as it places loads in a localized region of the inner race.

In other news.....something about fingering the sump?

I always enjoy Jakes replies as they are not theories but fact. Unless you think he is lying which is not his style.

OK, guys, not to steal any of the thunder from other inventors here, but I decided to tackle this one. Took me nearly 10 minutes to design a frictionless magnetic flux bearing. No more oiling systems needed, no ball, roller, or other contact-type bearings, and you can whack the car from the rear, front, side all you want and it will remain perfectly centered. I'm going to name it The Ultimate Solution. Is that name taken? I expect retail price to be approx. $19.95 if I can get the right Chinese fabricator. You're welcome. .

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Will there be a Tungsten version for $29.95 assuming you can get Schnell to help you?

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Will this retrofit require installation of a flux capacitor? If so, no thanks. I've seen how that works out. Your teenage mom will call me Calvin, and it gets awkward.

I have another Patent pending that I did just for the hell of it... No one would ever do it, but I decided to protect it anyway. You guys aren't that far off!!! :-)

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Thank you Jake for persisting with this subject and this thread .You have little to gain from participating and the silly posts must get irritating. Particularly when you go in to such detail to explain why things work/don't work. Your correction of the assertions like the one below help us dismiss the 'technical' nonsense which so easily convinces most of us. I totally accepted the cam deviation = IMSB wear assertion and nobody except you refuted it. Thank you for sharing your knowledge. And I am amused that some Poster came close to guessing the concept of your new product to address the misalignment issue. Identifying the misalignment was your work because even Martin discredits that theory ! I hope the OP understands that the 'fix' he bought(roller bearing) is unlikely to work any better than the hybrid ball bearing that just failed so quickly. Perhaps he will postpone further work on his engine repair until Martin's new bearing is available. I hope the OP will share the outcome with us all here on RL.

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He has a lot to gain, it's part of his business model.

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Bingo!

There are bearing retaining compounds which will accept a misalignment of .015" or more. As with any adhesive, preparation of surfaces is everything. This would require a slightly smaller bearing OD than the housing bore size which would be determined by the amount of misalignment. This would not eliminate the misalignment, but it would relieve the misalignment occurring within the bearing. Paul

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And, if you build a better mouse trap......

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A perfect example how more than one person can come up with the same idea without knowing what each of them is thinking. Same thing happened with the �Solution bearing�. A fellow RLer and I came up with the same idea (to use a simple bearing to replace the ball bearing in the IMS). This was before anything was announced from Flat Six. It�s documented on this board in the in my engine repair thread on the Canadian Forum. You took your idea, same idea we had, to an actual product and that�s excellent but people can and often do come to the same conclusion when a problem is presented. As a rough example, if the Wright Brothers didn�t fly, someone else would have and the airplane would have been invented either way.

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He would make a great marketing study.

It amuses me to see people that seem to resent Jake making any statements about the bearings or engines because God Forbid he may get a customer once in a while. Most on here will never have Jake or his shop touch their cars yet many have benefited from his posts.

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The two what? What? Did you say the two Yutes? Oh sorry...yooouuuutttttthhhhhssss. My cousin Vinny. Lovely movie

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We will let you know......or you could leave the original in and it might just last forever too, you never know.

Just a vendor hater that hates to see anyone profit from his hobby.. I made my profits from IMNSB development years ago. It hasn't been "part of the business model" since the release of the last development. I develop, its what I do, and I am paid per development without royalties or commissions, I don't have time for all the crap.

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Alberto Santos-Dumont was the first one to flight and operate a heavier than air, aircraft, but the publicity for him, wasn't the same as the Wright Brothers, is not about who have the idea, is about who's the one who do the advertisement, well this thing is getting out of topic. We should go back to the LN IMS Failure!!!!

Originally Posted by Schnell Gelb View Post "Thank you Jake for persisting with this subject and this thread .You have little to gain from participating and the silly posts must get irritating. Particularly when you go in to such detail to explain why things work/don't work." I have benefited from the many posts made by or corrected by Jake and Charles. During my diy engine rebuild Jake was helpful when others were snide,critical or worse. I have never bought anything from him or LN Engineering & probably never will. He knows that because I have said so several times here. My car has some LN upgrades that the P.O. fitted and they work well. There are a quite a few other very helpful RL contributors to whom I am most grateful. Sadly there are a greater number who merely clutter up interesting threads with their vitriol or banter. Back to engineering: The misalignment measuring tool - I think some posters think this means the bearing is installed misaligned? That is a different issue if I am understanding correctly. The new tool will (I assume) measure if the Intermediate shaft is parallel to the center-line of the crankshaft. It will be interesting to learn what the datum line is for establishing parallel .For example: is the crankshaft to be parallel to the top face of the block halves?This is an established procedure for conventional engines. And then you measure the IMS for parallel to the the same face ? Or is the parallel measurement direct between the crankshaft and IMS?

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I think there are two issues that are cluttering each other. The first is the new (to us) information Jake has added to the thread about a build flaw where things don't align correctly. The second is a proposed (alternate?) theory that the installer for the bearing that is the subject of this thread installed it incorrectly and it wasn't seated properly.

Un freaking believable. I took a much needed break while pursuing other vehicle projects only to come back and see that absolutely nothing has changed. I guess this will be another one added to the MOF list for CEF. Is there anything GOOD to say about the M96?

lol As far as your "MOF" list, blame Jake. He's the guy who has suggested compounding machining errors in the case creating a distortion in the IMS bore alignment. I'll take his word for it as he has undoubtedly measured hundreds of cases, and would be able to make that proclamation.

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Sounds nice??

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How about "At least it's not a Boxster."

How about every time you drive one you have a good time.

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Easy.....

How about " local gentry think you paid 6 figures for it"...and they don't even know it's 15 years old. ( I find the tighter mine twists, the more I like it) ...shhhhhh

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I hate to break it to you, but Boxster engines are also M96: M96.20, M96.22, M96.21, M96.24, M96.23, und so weiter.

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lol uh, yeah. 'twas a joke, hombre' ...back to the regular programming

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Where do you get that from? How do you explain that the ceramic bearing was fine for thousands and thousands of miles?

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Lets turn this one around... How do YOU explain an early failure when Jake has empirical data that shows a miniscule failure rate on that bearing. You admit the installer wasn't a certified installer...ergo, I can bet where Jake stands on this. The end of that taper appears to have been beaten, according to your photo evidence. Instead of your conjecture, why don't you do some digging and find a little evidence to support your claim? Oh yeah, there was that pesky detail of an accident...a rear-ender, no less. Who knows what happened to your car...I hate to say this, but I don't give a $hit at this point. What bothers me is your blanket assumption as evidenced by this thread title. The truth is this: YOU don't know what happened to your engine either...and you post a shaded factoid: it is a LN bearing...you had a failure. So you ginny up a saltry thread. You leave out many facts in this thread title...

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I didn't posit that theory, I was clarifying what has already been said in this thread for the person I responded to.

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No reason for you to stick around, then. Your absence - and the corresponding decrease in the amount of **** being talked about the 996 - has been wonderful.

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Come now, that's just absurd. Cite three sources and provide valid references.

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What taper?

never mind

I don't get you, bro. I come back and see more blown engine threads and more IMSB theories. At least this time there's a new theory. Glad you haven't changed.

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Well, Bro, maybe I can help you "get" me. Posts like these from a guy who ditched his (perfectly functional) 996 because he couldn't handle the pressure of a car with known issues irritate the hell out of me. 1) 2) If you don't have anything good to say about the M96 or the cars it's found in, GTFO. Seriously. Why do you enjoy hanging out here and trash-talking a car you couldn't handle owning? Go find some other bridge, troll. Aloha, "Bruh."

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Get the f*** out of here. We are here because we love our cars. Every mile I put on my green mean machine puts a smile on my face, and for the few people who have had bad luck with these cars there are hundreds of thousands of others who love them and drive them without fault. I will never sell my 911.

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Yeah, KK, I gotta tell you that this wasn't your finest moment. I appreciate your humor and the "stir **** up" mentality keeps things interesting around here, but give it a rest. If it's just gonna be a constant stream of 996 bashing, then take it somewhere else. I think you could really gain some traction on the Maserati forums. I seriously considered buying a 2002 Maserati Spyder at the auction this week until I read their forum's buyer's guide. It seems that if you go too fast over a speed bump you can damage a catalytic converter that costs $12,000 to fix - on a car whose estimated pre-auction value was $11,150. So see, I'm not just bitchin' about you, I'm offering a win-win solution. Besides, those rich Maserati guys are wound way tighter than us poor ol' 996 types, so I think the potential entertainment factor is way higher, too.

Guys, no need to beat around the bush; you would probably benefit from being a bit more candid!

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So they do exist...

Just for the record. Jake has said he has recently identified a manufacturing tolerance issue in some blocks which he found by investigating multiple failures on the same block. He now uses a special tool he designed to separate good blocks from bad blocks. He will only rebuild good blocks. He plans to sell this tool when patented. So it would seem it is entirely possible for the LN bearing to fail at 30k for a reason external to the bearing. The LN bearing could, under this scenario, be superior but fail due to uneven forces applied on it for which it is not designed.

May not be relevant in the OP case as the original bearing lasted 54k miles with no issues before it was preventively pulled out. You would think the original bearing would have failed long time ago if the block is misaligned.

The original bearing was a deep groove ball design. Deep groove ball is more tolerant(in theory) of misalignment than a roller bearing . That is why I hesitantly mention using spherical bearing again.It would be useful to discuss defects in this alternative for the few unfortunate enough to have this potentially expensive and presumably recurrent need to replace any of the current IMSB options.Just when we thought we were able to offer a long term solution to the IMSB issue ,it pops up again. Without a method of measuring the 'misalignment' and without any standard tolerance to compare to ,we'll just have to wait for Jake to show us?

To be clear, the plain bearing, (IMS Solution) did not fail in this thread. There have been ZERO IMS Solution failures. The IMS Solution is THE MOST tolerant of misalignment issues related the crankshaft/ IMS centerline than any other technology. Just wanted to clear the air there and make sure that everyone understands what failed. We will never know how it failed because the core that holds all the data is just being recycled to be sold to someone else. If it has a problem the next guy that finds it is the one who will buy it.

Thanks for correcting .

Hi Jake, Noticed your concern of the asymmetric wear on the inner race and how it may indicate a problem. I had my bearing (double row) changed out a couple of years ago (LN) and didn't return the old bearing. Apologies to me. But I just dug up the old inner race and it definitely is worn only on one side. Seems to make sense since this race is stationary, wouldn't it only fail on the loaded side and not indicate a machining problem? It is connected by a chain w/ tensioner, so I wouldn't think chain bind would be an issue. If the IMS can be off-axis and/or the bearing itself can be off-axis when pressed in far enough to be a problem (everything is off-axis), I can only shake my head. Seems to be the case here. (If so, a roller bearing wouldn't seem to help very much.) I have a careful watch on my oil and am a bit concerned since there is always a bit of residual glitter in the filter from the 1st failure despite having changed the oil 10 times in 20K miles and cleaned the pan. If there is another mode of failure besides just losing the grease in the OEM bearing, then I might need to think about a more radical approach to PM if the IMS Retrofit can have issues. Or it's rebuild time. Engine is still strong and smooth, so knocking on wood.

If the bearing is properly loaded and aligned, the entire race will carry the load, not just one area. Point loading is the big issue with misalignment and that's what creates the localized wear that you've noted. I have seen the inner race wear at all sorts of various points over the years, and it's not always in the region where it's expected. There have been times where the wear was concentrated 90 degrees from the area that should be the most heavily loaded. Dual row bearings also wear much differently than single row and we seldom ever see localized race wear like you speak of since there are two surfaces carrying the loads, not just one. If you had a dual row with localized wear, I'd be concerned with alignment issues.

Thx Jake, Many things are NOT intuitive, so I accept your views on this since you've seen so many engines and their issues. I'll have to be the eternal optimist and keep watching the oil, the old "causality vs. correlation" rationalization. If the few flakes trend starts upticking, then I will have figure out what to do, not driving being one of the immediate actions. For entertainment purposes, here's a pic of the double row showing the localized failure. Inner

This thread looks to be over one year since last post, but I recently had a LN ceramic single row p/n 100124200 fail on my 2005 997 @~30Kmi. Orig OEM was proactively replaced @40Kmi, showed no ware. Jake, are you interested in further details?

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Yes, but your first step is to contact LN with the details. That's the first step anytime you have a problem with any component. If you truly want to find out why this occurred, it's important not to start disassembly and etc. There's a considerable amount of measurements that need to be made.

Thanks Jake for your timely response. Who should I ask to speak to at LN? Engine at shop already disassembled. Previous owner had LN bearing and RMS installed, I have shop paperwork with date and mileage. What measurements can I have my current shop (LN preferred) make to check bore alignment? My thinking is bore OK based on 43k orig miles with no reported problems on orig OEM bearing. LN install was reported performed as proactive move. Inspection upon engine removal at 70Kmi showed no oil leaks around RMS or LN IMSB. Also of note, magnetic drain plug and spin on filter was installed, DT40 5W-40 oil changes @5Kmi was routine.

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I can't speak for LN, I tend to only deal with technical issues. With the engine disassembled you no longer have a perfect case to study. The measurements that need to be taken require the engine to be assembled, to be gathered correctly. This requires special tooling that I developed, but has yet to be mass produced and sold. Some of the dimensions can be taken with the engine partially assembled, and others with the engine apart completely. That said, the first phone call to LN (or any manufacturer/ supplier) should occur before anything is disassembled, and even before posting things to forums. If this doesn't happen the supplier cannot do their part, and often times nothing is learned from the instance. In that case you can suffer another failure later on from something that's not found during the repair. What I'm stating is just general information as I can't speak for LN. I know if I ever have a customer with my engine that has a problem, that I need to be the first person to know about it.

I might have missed this in your read, but LN has the Single Row Pro IMS also which is an updated design with a dual row of ceramic bearings. Just had this done in my 11k mile C4s. Hope is last. I think your failure is an rarity. Ln has stated an zero failure rate. Yours maybe the first.

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From what I gather the poster has the Classic Single Row, not the Single Row Pro (dual row bearing which fits the single row application). To date there's been no failures of the Single Row Pro, or IMS Solution.

Hope so I got a real healthy car and aim to keep,it that way I realize it's not a forever fix, but atleast I've got 6yr or 75k miles before change.

To date there's been no failures of the Single Row Pro, or IMS Solution.[/QUOTE] Here's to hoping it stays that way.

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Understand your guidance Jake. However, in my situation, knowing the LN single row ceramic was installed, the bearing was assumed to not be the source of engine problem. Assumption was timing chain or tensioner breakage. This is why call to LN was not made first. Only upon dissambly and discovery that LN ceramic had failed have I now started reaching out. I will call LN in morning, but would appreciate a contact in their engineering department vs. customer service if you can offer that up. From a technical perspective, as far as measurements of bore alignment, can you offer what crank shaft and IMS bore centerline should be referenced to a datum? Tooling aside, this should be the fundamental data set. I presume you have measured numerous blocks and perhaps you could share your findings with the community? Also from your technical experience, has there been history of LN ceramic bearing failing at <30K? I am more than willing to share pictures and my parts with you if you think it useful to analyze. Thanks in advance for your feedback.

As a matter of procedure, always contacting the manufacturer before going to the forums is good practice when you are going to be asking for help from the manufacturer, especially when there is no warranty. The M96 engine has more than one mode of failure - it's always easier to blame the IMS bearing, especially if it's been retrofitted. What I will say is if we find a defective single row bearing, it will go almost immediately (say within the first month/1,000 miles), not years or tens of thousands of miles later. More than likely the IMS bearing is a casualty of the other failure - with an open bearing, any FOD (foreign object debris) can result in catastrophic bearing failure. Please contact LN by email or phone - we will need the serial number of the bearing (to look up the registration) and any supporting documentation from the original installation for review to verify proper pre-qualification. I will look into this further personally.

When Instructing my M96 Engine Classes we focus on systematic diagnosis. When this is carried out, the root of the issue is exposed much more quickly, and the engine can be diagnosed without disassembly in 90% of cases. As an example, at the first sign of any timing issue, the engine should be rotated to TDC, then the green camshaft tunnel end plugs should be removed. If the camshafts are out of time on both sides of the engine then some issue with the intermediate shaft has occurred, and is creating a global problem for both sides of the engine, equally. If the issue is only creating a cam timing issue on one bank of the engine, then you have an issue limited to the one side. The next logical choice is then to pull the IMS Bearing flange, since it's next in line from a camshaft drive perspective, and everything is guilty until proven innocent. It does;t matter who made something, or how new it is, the process must not be altered. A shop that is adequately proficient with the M96 engine should get to this point within 1 hour of the diagnosis process. If they don't, there's only two reasons: 1- They do not know this specific engine well enough. 2- They want to take it apart to get a commitment from you, so you can't easily take the car/ engine elsewhere. I see the latter play out all the time these days. Lots of the people taking these engines apart don't know what kills them. Jumping in head over heels with a haphazard, full engine disassembly of the entire engine is not wise. There's no reason why this engine should have been taken completely apart, knowing that it had a suspected camshaft/ intermediate drive issue, be it a timing chain, or otherwise. I pluck cars off the lots of shops all across the country, all the time. This usually occurs after instances similar to this where someone pulled something apart. I see cars all the time with the entire engine disassembled and jammed into the trunk, and interior of the car. We call that a "trunk job". Why was't this noted prior to complete disassembly? That would be my question. To lock the crankshaft at TDC and remove the IMSB flange takes a total of 5 minutes to do. Also, before splitting case halves this flange also must be removed. Even if no one caught the issue before reaching that point, there's no reason why they went further than that, once they saw the condition.It does;t add up from my perspective. Charles replied to that portion of your statement. Never under estimate Charles, I have seen him do some amazing things for people who keep calm, and respect him. We've been working together for 17 years, and during that time I've also seen him deal with some jerks, too. I know from experience that he believes in the Golden Rule. He's a much nicer guy than I am, thats for sure! This is my proprietary information. I have learned not to share values like this publicly, especially when they are even loosely associated with a tool Patent that I have pending. Further, without this tool the values cannot be gathered in any other way due to variations in crankshaft carrier down positions that can shift the crank carrier in the crankcase, in regard to RMS bore diameter. You must worry about the crankshaft centerline aligning with the RMS bore, as well as how both of these effect the distances to the centerline of the IMS. What can be done is setting up the IMS shaft assembly in a set of V blocks, and measuring the values to the root of the sprockets, and the shaft on all surfaces. To do this you just need to gather all of your own data from 4 different axes of the shaft assembly, on all 3 drive sprockets. Compare these to the centerline of the housing bore inner diameter where the IMS Bearing resides. As an example of how wildly mis- manufactured some IMS shafts can be, see the results of this study back in 2014 that have been shared to dropbox, for use in my classes. We've seen some shafts that were even worse than this! This explains why some engines have had multiple IMS bearing failures after being repaired, and even some times after engine have been "rebuilt" (not by us!) IMS Shaft Study No. That said, keep in mind that at my facility we have carried out almost 600 IMS Retrofit procedures, including the very first one. Of those the majority have been with the IMS Solution, since its the only product I have used since 2011, and I tend to go overkill with everything that we do. Not only that, but its my Invention, and there's a reason why I spent over a decade perfecting it. Of those 600, around 180 of them have been carried out with the exact same product that you have experienced disappointment with. This is more than any other company in the World, by hundreds of percent. The last of them was in 2011, some 5 years ago. Of those 180 units we have had ZERO failures to date. If the Classic single row had issues that were not related to collateral damages, then by the law of averages, we would have seen not only a failure, but more failures than anyone else- this hasn't been the case. The same goes for Callas Rennsport, the #2 installer in the USA, who has also not had a single failure. This proves that a proper procedure, coupled to not retrofitting every car that comes in the door is the key to success with this procedure. Both of our companies share the same attention to detail, and carry out similar exhaustive pre- evaluations before engines are retrofitted. We don't treat the job like a brake job, just throwing some parts at it, and sending the car down the road. In general a shop does;t care, as its not their product, AND if it fails, well, they just stand to make even MORE money from their customer (yes, I have had a shop owner in my class say that out loud). If an engine fails even one aspect of this evaluation, it is not retrofitted. Doing this gives the best chance of success; because, remember, everything is guilty until proven innocent. A good example of an issue like this is a car that came to my facility for a full reconstruction a couple of months ago. The owner stated that he heard a growling sound from the engine, so he parked it (smart man, he didn't drive it to death). When I disassembled the engine, one of the first things that I did was quantify valve timing, which was about 4 degrees over advanced, and equally on both sides of the engine. Knowing that the ONLY way that cams can see additional advance is by having the IMS drive chain bee too taut, my very next move was to remove the IMS chain tensioner. When I removed it, I found that it has basically exploded, and then had jammed int a hyper extended position, where it was about 3/8" longer than it was supposed to be, and it was no longer functioning hydraulically. I found this before the engine was even removed from the car! After contacting the owner to tell him about this, and gaining permission to go more invasive with diagnosis (in writing) we pulled the engine and pulled it apart. I knew this had to be done; because the failure HAD already broken the IMS tensioner paddle, and the only way to address this was to pull the entire engine apart to facilitate repair. When I pulled it apart, guess what? The IMS Bearing was also failing, but only from collateral damage related to the chain tensioner failure. So, as you can see, forensic mechanicology must be exercised, along with exceptional judgment, if one intends to gather the full story from any failure associated with the M96 engine.

Jake , Thank you for taking the time to give these anecdotes. I have read many of these threads and benefited from doing so. I acknowledge that th time you spend writing these Posts is time you probably should be spending on work you already have piling up in your workshop. The anecdotes about chain tensioners and paddles are the most useful part of your Posts for me because they give a specific example and cause for a Mode of Failure that is otherwise classified as "IMSB damaged by FOD" . The specifics of the tensioner failure also make clear how 'sensitive' the M86 is. Having a tensioner over-extend by 3/8"(9.5mm) does not seem lke much until you read what the damage costs to repair. In this specific case, if an inexperienced person dismantled this specific engine, I doubt they would have noticed or understood the significance of they did. So is this a new number in the "Mode of Failure" list ? Thank you for explaining to us.

Nope, I've seen it many times, first around 2007. We see it, I'd guess 3-5 times per year.

Jake, is there an easy way to tell (if you could share) whether the tensioner failed first or the bearing failed first? A failed bearing will allow the IMS to wobble and that would cause the IMS chain to stretch, and in turn allowed the tensioner to over extend?

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Now that it's all apart, no way. This has to be determined during disassembly, through very careful inspection of where debris ends up, and other clues. Sometimes it takes me two days to determine things like this, and sometimes it's damn near impossible to conclusively determine what happened first, the chicken or the egg.

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That makes perfect sense. Thanks!

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If these run-out numbers are taken from shafts that came off the assembly line, there's something wildly wrong with the mfg process for this shaft. Or, the QA isn't being done. I can't see any way that normal wear on the engine would cause this kind of run-out within 100k miles in an otherwise normal engine. I would say that the run-out for the shaft should be +/-0.0005" for that size shaft when new, and at end-of-life, the shaft should not exceed +/-0.002" in worst case. I would like to see some tests from brand new Porsche part IMS shafts, as you said it's hard to quantify if this is a chicken or egg issue, but if these run-out numbers are for real, I can see where all the catastrophic damage is coming from.

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The brand new, M97 shafts are the best for runout, even after use. These results are very real. Some came from shafts that had lost one or more IMS bearings, others were just good shafts that had not seen a failed bearing, and were being evaluated for use in an engine reconstruction. With this, we've quantified yet another contributing factor to IMS Bearing failure. This one is the biggest of all; because, it can't be measured without engine disassembly. So, this one is most worrisome with a single row bearing, that has much less load carrying capability than any other, and will fall prey to the runout monster most. With runout the bearing is working to control not only longitudinal and lateral thrust, but also to control an elliptical condition, where the shaft is not turning true. This creates vibration as well, which helps to weaken the cage. I first noted this when developing the IMS Solution, as one engine always had a small polished spot on the face of the IMS Solution flange, and we worked for the better part of a year to eliminate that. We changed hardness, changed the coating on the flange, and even changed where the oil holes were positioned in the flange, but nothing ever omitted it completely. Finally I disassembled the engine and found the shaft had runout. We swapped the shaft and that polished spot never came back. Nothing else was changed, we just wasted a year of our lives. That said, the IMS Solution handles this runout with no problem, and through that development we learned that the wear will only lead to one area of the flange that sees a polished surface in the coating, no measurable wear existed.EVER! The IMS Solution is an over built, super heavy duty part that can carry this load, and control a shaft with moderate runout. We've already proven that, even though we had no idea that we were doing that, at the time. Lots more could be posted about this, but we'll save that for a TSD later down the road. This further proves that "lubrication is not the problem". Throw as many oiling devices that you want to at the engine, and if the shaft has runout, it'll still kill the bearing. Mechanically a single row bearing cannot live through it. Also, note where some of the runout is... The main timing chain drive for bank 1 camshafts.... So, we also learned why we see bank 1 main timing chain failures. Ding...Ding...Ding. Knowledge and experience like this is what you receive inside my engine. Been there, solved that.

Jake, do the factory remanufactured M96 engines that were made and installed as replacements into the 996.2 during the 997 era use the M97 shaft or just the larger bearing? I realize that these engines (and the M97's) seem to have less issues but is that a large part of the reason why? Thanks in advance for any insight.

Only if remanufactured post 2006. After 2006 ALL engines were remanufactured with the M97 larger diameter IMS Bearing.

So it's really a bad shaft not a bad bearing. Would this runout also cause premature failure of the timing chain tensioner? Seen more posts about that then the bearing actually.

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We can't generalize. This is just ONE of over two dozen potential contributing factors that add up to equal IMS Bearing failures. This finding was the key to understanding why some engines lose more than one IMS Bearing.

Perhaps there is a wide variation in run-out of the shaft and at different locations along it's length ? We have just discussed the outliers - the majority of shafts that are acceptable run-out cause no short-term failures .The extreme ones Jake had kindly mentioned do. But what about all the in-betweens ? For the in-betweens - the vibration may not be severe enough to be immediately catastrophic but it must surely shorten the life span of the IMS bearing and perhaps other components in the IMS system ?Once the IMSB does wear ,that too will cause even more vibration. So this vibration increases the LOAD way beyond the design limits of the single-row OEM bearing(not a lubrication problem). So a bearing with a much higher load capacity may be a kind of insurance against run-out? If so, doesn't this favor using an RND roller bearing instead of a Classic Single row or even Single(staggered 2 row) Row Pro ? I am not trying to start an IMSB flame war.It just seems logical ?

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Jeez,,,, this is sad. And, again - thank you for the research and documentation of this stuff. I know it takes time, and effort but the results must be satisfying to find so many root cause issues that combine to cause failures. Scary to think that back in the 80s Porsche built aircraft engines(not many!). I'm sure the tolerances were much tighter, but the overall picture of this failure type sure makes it look like all those who wail about the bean counter take over in late 80s caused a lot of heartburn. Things I now know, that I can't unlearn about my new car. Gulp.

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While anything has more load carrying capability than an OEM single row bearing, until you remove all the wear parts from the equation, nothing "comes to the rescue". The IMS Solution doesn't care about these types of vibrations or even moderate runout. That's why it is, and will always remain, The IMS Solution.

Compliments to all. This last discussion has been very informative without all of the usual drama. I learned a lot reading these last few posts.

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I used to do a lot of QA for massive disk drives built by IBM back in the 70s and 80s. These platters were ~26" in diameter, so as you can imagine, we could not tolerate any run-out or suffer constant head crashes. Well, after a few years, even though we specced a real good set of bearings, and very true shafts - we started to have HDI problems and discovered that yes, run-out was the problem. Led to a huge, massive costly recall or field replacement of many bearings. The takeway from this little story is that NONE of those shafts should be in customer hands, or engines. Evar. End of story. If there's a IMS out there with .004" run-out it's junk. Even .002" run-out on that length of shaft is marginal. Anything over .001" would be a reject. Which leads to the conclusion that Porsche wasn't doing any cont process improvement(sustaining engineering) once the part was on the mill, that was the end of that and whatever came off the mill(machining IMS), was put in an engine. There's just no excuse for a part variation allowance like this from a major maker of high perf autos. No excuse at all, and yet we have examples in that photo array of I would say 5-7 parts that are in the field and are going to blow up an engine if installed. No excuse(did I already mention that?)

O.K. this is yet another justification to install the "Solution" - because it is tolerant of a shaft defect(& others yet unknown?) that alternative bearings are much less tolerant of. Part of our reluctance to dismiss all other IMSB alternatives and just install the Solution is the cost because it is Pro install only - no diy. I am fine with that. Just a pity. But if I was offered a diy Solution at a reasonable price I would remove my (new) single row IMSB with my LN tools, buy the new Faultless tools and install a Solution . I understand why Jake/LN will not do this to protect their product reputation from screw-ups by diy people(like me !) The only high-load option I have for a diy upgrade is a cylindrical roller bearing kit ?

ims solution isn't DIY? though we just had a thread on it....

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You can buy an IMS Solution kit from www.rndeuroparts.com when units are in stock. Though the product won't have any warranty unless installed by a Pro, you can still buy and install one... You'll even receive product support from The Knowledge Gruppe to help assist you with any complications.(only if bought from RND!) The Solution has become extremely popular in the last 24 months of the 5 years that it's been on the market. Wholesalers upped their purchase orders, and they still sell out in 45 days or so. The last run was finished in July and was sold out in less than one month, today no one has any in stock, but another run will be done in about 3 weeks. My engines have IMS shaft assemblies that have been checked for runout, and have since the beginning. That's probably one reason why we've never had a failure. The he other guys, well, they learned about this problem at the same time that you guys did. They wouldn't have figured it out on their own- that's for sure.

Sorry ,yes - Pro install to get a warranty .

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Can bet Porsche knew in about 03 or so. I wish those run-out shafts were avail to the court during the class action. I would love to see someone up on the stand with a group of 16 new shafts and have 5-7 of them fail their own spec, whatever it might be. No way is >.003" acceptable to any machinist these days. That's the kind of slop I would see in a 1940s Buick engine. This also lends some strength to the idea that these failures happen at low mileage examples. There's no way that slop is going to run +50k miles like that. I'm betting that an engine that makes it to ~50k miles has a decent shaft in it and a dual row bearing. Conversely, an engine with a bent shaft might go through 3 bearings in 100k miles. The same failure mode causing the same damage due to the same crap tolerance.

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This is how theories become internet realities. The other end of the IMS is a simple bearing and since they tolerate a wobble better, the ball bearing on the other end would see a lot less than the total runout of .003". We need hard data from a first hand experience before "speculating".

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If you didn't go to the drop box and view the pictures with the run-out labelled I guess you're right about speculation. Since Jake and Navarro have some reputation here, I'm relying on them not being complete bone-heads on how to measure run-out. Couple that with the failure rates and failure modes and we are way beyond speculation. Run-out is a killer for rotating assemblies. I've been down this road before. The failures of the IMS are not a theory, they are very real.

"We need hard data from a first hand experience " Jake just gave us that. In terms of fixing our own engines (which is what interests most of us?) - the next stage is to learn the best way to measure the run-out of the shaft. I doubt it is just a standard test on V-blocks +dial indicator because we are measuring run-out not just roundness.

Shaft defect theory is something that helped put me at ease on this whole M96 thing. I get it that the M96 has interior parts made of chocolate - that's ok. What I want to do is prolong its life and plan for the eventual rebuild with as little stress & drama as possible. And the most driving fun permissible. So my plan is: - yank ball bearing IMS retrofit that's a few years old (done) - install IMSS, get full engine review (done) - get on an oil regimen that looks after the high temperature risk to the M96 (done) - convert to low temp thermostat (pending- next summer) - save for rebuild of M96 to a 3.8 or 4.0 spec (hopefully 5+ years away, but be ready for it as soon as 2018) - drive the ever loving **** out of the 996 (hooning in process) It's great to hear about the proliferation of the IMSS - that tells me consumers are learning what is up with the ims design flaw & used inventory is being upgraded to improve the quality of the cars. As long as the other 3,453,895 modes of failure don't flare up the 996s should leapfrog 964 values

"yank ball bearing IMS retrofit that's a few years old (done)" Done with what ? NUP204E ?

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I'm a tremendous hack when it comes to wrenching. The install was done by a certified tech, warranty in place on the imss. Old retrofit is somewhere in an LNE stockroom.

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Since very few of these IMS are truly 'true', what would you consider acceptable/permissible to use in an M96 engine: less than .002?

It would be interesting to know what the UOA of the OP's oil when he first noticed the large pieces of IMSB race on his magnetic drain filter. I am assuming iron PPM would've been pretty elevated.

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Sorry, but no oil analysis was done. One mechanic initially suggested that, but because there were already visible ferromagnetic particles (iron) on the drain plug, we figured an oil analysis wouldn't tell us anything new.

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How about sending the shaft to Jake for run-out check? If I were in the LN company, I would be learning a lot about the IMS in your engine right away. Measurements should be taken consistently to compare readings.

I sent the ims & their IMSB to LNE for inspection prior to my build. they sent me shiny new parts.

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Quite the contrary.There's a ton more to UOA than wear metal results. Viscosity, TBN (is the oil dead) TAN (what were the acid levels in the oil?) and fuel contamination percentage are just a few of them. Watching these things, and seeing how much of the anti- wear package remains in the oil completes the puzzle about whats truly going on.

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(Just asking) is it really that telling though? Isn't it only going to tell you that one OCI and wouldn't it take more than one interval to cause a problem? For example the PO followed the original 15k interval, but then the unlucky new owner changed it religiously at 5k intervals. Even if it went at the end of the interval, shouldn't the oil come back looking pretty good other than what the failing motor dumped into it?

No way. An engine can have an IMSB that has has yet to hit stage 1 failure, and the bearing can go through all 4 stages of failure within one 5K service interval. I have seen this over and over again, and witnessed it first hand with a lady's Boxster that we serviced locally. Filter, sump and UOA perfect at 41K miles, passed the finger test, and the black light test, too. At 44.5K miles the engine lost an IMSB out of the blue. She owned the car since new and we took care of it for 20K miles. She refused to listen to me, and she paid the ultimate price, and the car ended up as a race car when she bailed on it. It was at that point where I required any local that wanted its to service their engine to carry out an IMSR procedure.

I like the sound of that. I have been pulling my filter at about 2500 miles and checking it out. Then changing the oil and filter at 4-5k. I am pretty sure oil can last very long (10k plus miles) if the engine is not running poorly. But that is just it, how do we know from one week to the next how well the engine is doing. Everything could be running smooth with no noises or power loss, but the oil could start to show something that is not obvious. I am just hoping to catch something at the earliest stage at the cost of more oil changes and getting under the car and pulling the oil canister. Given the potential savings, I am willing to take these extra steps. I also understand that my IMSB may just blow up and their is nothing that I am doing that can prevent that. But two new wheel bearings in the front, car drives like a dream and that is all I try to think about for now. lol

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I was referring to your post only.

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And I posted in reply to your post only. We have actual measurements here, we have literally millions of hours of NRRO and repeatable run-out(pretzel shafts) history to work with. If you think it's an internet theory - you are way wrong.

After reading a 217 posts of this thread, I came to the same conclusion as 3 years ago (post 48 of a thread called "IMS bearing?"......) The problem is not the bearing.....the problem is something else that causes the bearing to fail.........

O.K. but while we are hunting for the Holy Grail of one or more multiple (fundamental) causes of IMSB failure, we need a palliative. The best still seems to be a lubricated plain bearing called "The Solution" ? The next best alternative is debatable.

The IMSS sounds great, but due to out-of-stock issues and the nearest certified installer being some 260 miles on an interstate going through heavy road construction pretty much all along the way, I'm going with the Gen2. LIFE ON THE EDGE!

Jake mentioned that The Solution will be back in stock within a couple of weeks - Call RND or SSF ? IIis (above)is fitting LN # 106.08.2.2 for the noobs . This is a confusing product because the phrase "Single Row" is used in the name but the description says it is "dual row". So which is it ? I'll try to explain but welcome clarifications: The LN Gen 2 Single Row Pro replaces the IMS bearing on shafts that were originally fitted with simple single row bearing (like generic # 6204). But the upgrade replacement from LN has an unusual staggered dual row of bearings - not exactly double row ,but close. That is why(??) it is called dual, not double row. The 1977 SKF patent for this unusual bearing is US 4055371 A https://www.google.com/patents/US4055371 Because the staggered 2(dual) row bearing has a greater number of ***** than a single row bearing . it has a much higher load capacity than the original single row. But the load capacity is slightly less than a comparable, conventional double row bearing . Because this dual bearing is deeper than the original single row ,it requires a different retaining system. There is no space for the original simple circlip on the face of the bearing. A clever spirolock is used instead and special installation tool kit is required. http://imsretrofit.com/gen-2-single-row-ims-retrofit/ The theoretical alternative to the staggered 'dual' row bearing to achieve a higher load capacity is a cylindrical roller bearing - for example: http://lnengineering.com/products/im...rofit-kit.html There are no staggered row bearings from other sources than LN. There are single row ball and cylindrical roller bearings for single row IMS shafts from others.For example: http://www.pedrosgarage.com/Site_2/TechnoFix_DOF.html http://tunersmotorsports.com/trs-dev...rect-oil-feed/ The warranty & Pro-install issues are a separate subject. I hope this helps with the basic understanding of the differences for noobs.Feel free to improve ! And yes, I have replaced the IMS bearing on my own engine,have the LN tools etc........

Thanks, Schnell Gelb. To clarify, this is what's in store for my car: http://imsretrofit.com/gen-2-single-row-ims-retrofit/ professionally installed by an LN-approved, well-respected local shop. Jake, to bring this thread hopefully to a TL;DR level: Are you saying the IMSS is the only recommended way to go now?

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Here's what he has to say: http://theimssolution.com/2016/09/16...t-vs-solution/

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I am completely biased toward the IMS Solution for many reasons. Primarily because its the most simple way to control the IMS assembly, and it has no *****, no cage, or any of the wear parts of a ball, or roller bearing. The other reason is because I have a HUGE chunk of my life in this invention. In fact, I have spent more than 1/4 of my life developing, and perfecting this product. Traveling 240 miles to a Certified Installer isn't bad. I have a 996 here now that came from Vancouver BC, over 3K miles away to have my team install The IMS Solution. We don't give away Certifications. We hand select (by invitation only) those who will be accepted to begin evaluation enter the program. This is done in my hands on classes, and attendees have no idea they are going to be selected. If we are impressed in the class, and the shop has a flawless reputation, then we move forward with the Certification processes. These include an on site visit, practical application, and written examinations, and each installer must conform to our Code Of Conduct with every single job with no deviation. If we receive one complaint from a customer of one of these shops, and can quantify it, the Certification is pulled immediately. Is the IMS Solution the only way to go? Well, I invented and developed it for my engines, and I kind of wish I hadn't released it to the market. As popular as it has become my wait list for a turn key engine would be two years, not just one. Maybe more. But, its never too late to hoard it!

I have a new RND engine and went with The Solution. It made sense to go the extra expense because it's a zero-miles engine with beyond-OEM-durability upgrades and I plan on keeping the car till it serves as my coffin On a factory-stock engine with miles on it, and/or not plans to keep the car forever, I would probably go with the LN retrofit. I had the original LN single-row in mine for 30K miles and it came out looking like new, and the Pro is that much beefier.

I thought about driving to Georgia to have Jake's team install the Solution but they had a 3 month waiting list at that time. So I drove from Austin to DFW (185 miles) to have a certified installer (Mayo Performance) do the job. Couldn't be more pleased with Mayo's work and the Solution!!

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Chris and the Mayo team represent the IMS Solution well! We maintain that 3 month wait, sometimes longer. No rushing around here, and it's not about how many we can do... When we crossed the 500th installation it was clear that it would take a decade for anyone else to catch us :-)

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I agree with pesuazo's comments, starting to come to the same thoughts. I have done lathe work on crooked pool cue shafts and seen the dramatic effects caused by poor roll out... Obviously, wood shows roll out much more dramatically than metal, but ultimately the same concepts apply. SPECULATION ALERT! A batch of bad shafts beating up on IMSB's sounds more plausible to me than bad batches of both double and single row bearings. Variances in spec with the shaft itself would explain failures from both types of bearing, which would also explain why more cars with single row have the issue. Could also simply be that the (possibly) offending bad shafts happened to arrive at Porsche in 2000-2001. Stands to reason that double row bearings would likely be more capable of handling a wider spec range shaft and possibly prolong the inevitable failure of the IMSB. It would be interesting to note if the average mileage of failures on cars w/double row bearings is later than the average mileage for single row bearing cars? (sorry if that's been discussed, but this is a long thread among a plethora of other long IMSB related threads) Furthermore, if this theory is correct and a microscopically "bent" shaft could indeed be the true villain in this saga, does the roll out in the shaft end up putting more load on the bearing's thrust load or the vertical load capacity? My inclination is to believe that a cylindrical bearing with wide contact patch would perform better in a car with an IMS shaft that has enough roll out to instigate a bearing failure. And (another guess here) I think thrust load differences on the bearing would be minimal when comparing a bent IMS shaft vs. a straight shaft, but the vertical load would be significantly different. (unless the roll out gets progressively worse over time, then all bets are off)

Meh, occam's razor and leaving it at a flawed initial design that manifests in myriad ways does it for me. I see little utility in theorizing on the issue when hard data is being kept private by Stuttgart. Just cover your own risk to your satisfaction and move on with life imho.

An interesting proof of the IMS runout theory has been provided bu JFP.The short version is: M96 shafts are variable in runout. M97 shafts are not. " Originally Posted by JFP in PA View Post You are missing the point. Brand new, unused M96 shafts, right out of the box can demonstrate this run out. Shafts removed from running engines with perfectly good IMS bearings show run out to varying degrees, while many well used M96 shafts show no or very little run out at all. On top of this, the shafts from used M97 engine's do not show this tendency. So basically, if you got an M96 with a shaft with run out, and it happened to be a single row engine, the odds were stacked against you being a happy camper." Reply: "Here is a hint of how to qualify a would-be M96 engine rebuilder: "Would you let me see the IMS runout test on my shaft? And what about the other 6 items on the list of 7 supplied by Smallblock My guess is that only well equipped and trained machinists would be able to do this test.The average engine rebuilder would not have the correct equipment ,nor even know what to look for. The pragmatic suggestion is to use a new M97 shaft when rebuilding an old M96 ?How else do you buy a garuanteed straight shaft? Then you do not need such a fault-tolerant/expensive bearing ?Dang - I did not know this when I rebuilt mine - next time.....:-) " From: http://986forum.com/forums/general-d....html#poststop

Resurecting this derp of a thread of lawyers using Aristotelian logic and mechanical upherisims by garage mechanics who seem to not understand that a raw egg, uniquely designed to absorb shock, is limited by its design to evade shock from forces that could destroy it. Has anyone come up with a definitive answer to why the IMS fail? Because if so, Porsche can be sued. Just saying.

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O...mg...

^^^ +1

TOOOOOOOO the Bat Cave Batman!

Hey Everyone, Im new to the Porsche world and a bit confused about the IMS bearing solution. Can anyone comment about what are the better and best solutions. I just bought a 2002 911 C4S with 96,000 on it. Owner claims to have had the IMS bearing replaced at around 30 K and I have the bearing ser #. Checked it with LN and they say it was replaced in July 2015 with a ceramic bearing. I just did a pre-purchase inspection. No metal in the filter or the pan, Borescope showed no borescore. Records show oil changed every 2500 miles. Talked with LN and they say �5 years of 50K for replacement of the ceramic bearing I currently have.� Choice 1. Replace with Ceramic LN bearing. 800.00 plus labor. Choice 2. Replace with LN $1900.00 oil fed bushing replacement solution 5 years unlimited mileage solution. Choice 3. Use TUNERS oil fed - steel ball bearing single row replacement solution for $800 plus 2500 in labor. 1.) Is there a Porsche master mechanic that can asnwer this question? 2.) Who does anyone recomend in S Florida will properly install the 1800.00 LN oil-fed pressurised bushing solition? Thank you!

The topic of IMS bearings is very polarised on the forum with strong opinions in pretty much every direction. Every time the subject comes up it will create a storm. I suggest you read what have already been written in the IMS threads, the subject is rather exhausted.

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Search "PCA IMS" on Youtube and watch the 4 part series there. See also www.rennvision.tv The IMS Solution Certified Installer that I trained in S. Florida is Dave Till, at Till's Automotive in Ft. Myers. Dave has a flawless record of making the right decisions, recording his registrations, and pre- qualification procedures. Porsche Master Mechanics were never trained by the factory on the IMS Retrofit procedure.

@Boat1dean Listen to @Flat6 Innovations . Best advice I can give to a new Porsche owner.

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No we were not, but some of us know a good design when we see it, choose the IMS Solution and you will never regret it..

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I agree, install the IMS Solution and never worry about the IMS bearing ever again. Install the UAOS and never worry about the AOS again. Listen to Flat6 Innovations and learn LOTS more about your 996.

This may seem out in left field but: I've replaced many bearings on bicycles and motorcycles in the wheels, suspension and motor. Sometimes they go in easy and sometimes they are way too hard to press in. When they're too hard to press in, they don't spin smoothly. if you remove them, they do spin smoothly. I would never trust one of these IMS ball bearings that was too tight no matter how fancy the bearing is

Which is why I�d only have an experienced (Porsche 996/997) shop perform the bearing replacement.

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Maybe but you just don't know who to trust

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Maybe but you just don't know who to trust

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You trust the people who were hand picked by the inventor to carefully execute the procedure. These people were trained about housing bore sizes, measurement procedures, and specialized installation. They have a direct life line right back to me, if in doubt, they ask before moving forward. They know their certification that took time, money, and a 4 day trip to my world for evaluation is on the line with every installation they perform. They don't want to lose that, and they know that there's no second chances extended.

I don’t think Jake is easy to impress. So if an installer impresses him and then gets invited to learn from him how to install the IMS Solution, and then gets certified…trust me, he’s good enough for you!

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1,440 people have attended my classes since 2008. Of those 40 have been selected to continue on into the Certified Installer program. Of those, 34 have made the grade. Of those, 2 made a single mistake and I yanked the certification immediately. Neither mistake led to damage, or a failure, but they didn't follow protocol, and got my boot in their ***. Some things in this world still have consequences.

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So, 2.3% make the cut. Nope, you ain’t buying your way onto the certified installers list. You have to be the best of the best. If Jake says they’re certified…you can trust them.

I would like to know how ball bearings survive in motorcycle engines with all that potential crap floating around in there? the pic of the bearing at the beginning of this thread looked like it was crushed to me