poll: which IMS is least objectionable?

All else being equal, would you rather have a car with the 2006-8 large IMS bearing, which fails less often, but can't be replaced without tearing the engine apart, or the 2000-2005 small bearing which fails more often but can be replaced more easily?

My favorite IMSB is the one I currently have that hasn't failed!!(the small one)

2000-2005. Replaceable Bearing.

Likewise....2000-2005 small but serviceable bearing. I would immediately book the car to have The Solution installed. Then no more worries.

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Do you have The Solution installed in yours?

This poll question is quite counterintuitive in that both answers have positives. For one, if you own a serviceable M96 single row bearing, you can change it out for the proven IMS Solution plain bearing without the need of opening up the engine. However, if you base it solely on the quality of the bearings, then it's quit clear in the Porsche community that the M97 large single row bearing is superior to the older M96 single row. But if I had a choice, I would rather have a serviceable bearing that I could put in the IMS Solution.

I've played that question out many times as I start window shopping early 997s which are now dropping into the high $20Ks. I've researched the hell out of the M97 bearing issue and it is beyond rare to see an M97 large bearing fail. In the 997 forum under the IMS bearing poll, up until recently I think there was only one failure reported on a '06 and later car - and even that reported failure was suspect. There were fair number of '05 failures reported as you would expect from a stock small single row bearing. LN has recently posted a photo in another thread of a large bearing that was starting to fail; so it can happen. But it is really rare. With that in mind I basically consider a 2005 997 to be worth $1500 less than an equivalent 2006 since that's about the price of replacing the bearing with a regular LN single row upgrade. Other than that I think of them as being equivalent and would be equally satisfied with either engine. I like the LN IMS solution, but that a lot to spend on a fix for a failure mode in an engine that is more likely to fail from bore scoring than IMS bearing failure. To me, the IMS bearing issue was something that was generally overblown even though my car did get the LN dual row bearing installed at 94k miles with the clutch as a precautionary measure - btw the original bearing that came out looked great and the car now has 124k on the clock. I think the real issue these cars will be facing as they continue to rack up miles is bore scoring - which does not have a nice effective "bolt-on" fix. I definitely have concerns, especially on the 3.6/3.8 engines. Off-topic, but if you have not yet seen the four-part Rennline video series Jake Raby has posted on YouTube, it is very informative.

While the larger bearing can't be replaced without tearing the engine down (and splitting the case halves), it doesn't need to be replaced - just remove the outer grease seal (you can do this without splitting the case halves) and you're good to go. The failure rate of the large bearing is so low that it's insignificant. This can't be said for the smaller single row bearing (the one that lead to the class action suit). The other problem with the smaller bearing is that even if it hasn't reached "stage IV" of failure, it could have spread a bunch of swarf through the engine before being replaced - I'd stay away from the '01 - '04 engines at all cost (unless I had already unknowingly purchased one - in which case I'd probably look to do the IMS Solution).

Also check engine serial #, you may get a car that has a factory replacement that has the large bearing and fewer miles on it.

As others have said - the best solution is to replace the factory bearing with the IMS Solution and move on with your life. With that in mind, a serviceable style bearing that doesn't require splitting the case to do the swap is definitely preferable.

" With that in mind, a serviceable style bearing that doesn't require splitting the case to do the swap is definitely preferable." Not if it's already failing it's not...I realize this seems obvious, but in most cases it isn't. Many people who buy these cars know nothing about the IMSB (or it's stages of failure) - if the car runs and sounds ok ("oh that tick isn't a problem, it's just a sticky lifter...") that means everything is just fine... we know better than that...

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LOL. True. So, let me clarify that my statement assumes both bearings are healthy.

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Or worse, you buy one sight unseen, it arrives with "Apollo 911" on the side.

Wouldn't the least objectionable one be the dual row in the first iterations of the 996?

The 997 bearing is better because the headlights are round. Now seriously ... Charles Navarro of LN Engineering provided this explanation a few months ago about how lubrication works. With a larger bearing, the bearing surfaces are operating at much higher speeds. That's why I vote for the 997 bearing. https://rennlist.com/forums/996-foru...l#post15663268 "It has to do with hydrodynamic lubrication. At higher surface speeds, less oil is required to properly lubricate the bearing. Think about it this way - there is a fixed load on the bearing. At higher speeds, the ball spends less time at a given point as the ball is rolling (or sliding) faster. This is obviously an oversimplification, but it gets the point across. Porsche realized this and went to the 6305 bearing to increase the surface speed, which as a byproduct, also restored the load capacity the original dual row bearing had."

[QUOTE=911Syncro;15875696]The 997 bearing is better because the headlights are round. Now seriously ... Charles Navarro of LN Engineering provided this explanation a few months ago about how lubrication works. With a larger bearing, the bearing surfaces are operating at much higher speeds. That's why I vote for the 997 bearing. https://rennlist.com/forums/996-foru...l#post15663268 "It has to do with hydrodynamic lubrication. At higher surface speeds, less oil is required to properly lubricate the bearing. Think about it this way - there is a fixed load on the bearing. At higher speeds, the ball spends less time at a given point as the ball is rolling (or sliding) faster. This is obviously an oversimplification, but it gets the point across. Porsche realized this and went to the 6305 bearing to increase the surface speed, which as a byproduct, also restored the load capacity the original dual row bearing had."[/ Bearing load capacities increase with the size of the rolling element. As far as speed goes it is only a partial factor. IMSB's turn at very low speeds for typical ball/roller bearings. IMS shaft turns at half crank speed so 1000-3000 rpm are the norm. Your alternator turns at 3-5 times crank speed and live long happy lives. More important is EHL. Elasto-hydrodynamic-lubrication. This is the bearing pumping it's own oil at the wedge just ahead of the ball/race junction. Ball bearings force the oil out like the nose of a boat,roller bearings with their thrust flanges do a much better job of containing the oil where it's needed most.

I guess I'm confused. Why would you want to have something that has the obligation of replacement not if but when? In full disclosure I have an m97 replacement in my 02 done by Porsche under CPO in 08....I don't even think about IMS.