CV joint failure after lowering

So last week I brought my 996 C2 in for installation of an Ohlins Road & Track suspension setup. Final result is that the car got lowered approx. around 20mm in the front and 17mm in the back. All went fine. Car drives great. Firm ride with great souplesse (11 clicks in the front and 12 clicks rear) Yesterday I noticed a grinding noise on the right side when making sharp left turns, especially under acceleration. Right turns are smooth as should be. I did a quick search to see if I could identify myself the problem and came accross the following posts. https://rennlist.com/forums/996-foru...d-turning.html https://rennlist.com/forums/996-foru...hand-turn.html Transmission mount seemed to me not the issue as I upgraded them 5000km ago. But the posts above made me suspicious about the CV joints. And indeed, I found the evidence of at least the right CV joint in the rear being in failure mode as I found traces of the sticky joint grease on the edges of the fenders and inside the wheel well. Probably the CV joints were already in bad condition. Lowering the car resulted in a different angle of operation of the joint. Also the change in angle also resulted in extra longitudinal forces on the joint (correct?). This was probably the final push for the joints to fail and to start grinding when turning and accelerating hard. It is most likely that the left side is also in a not so good state. I will have to replace the whole shaft. Is there further any issue that will cause a problem for the new shaft and CV joints because the car is lowered? Any adaptations necessary to the shaft? Or should all be fine as is?

I had done the X74 suspension on my old 996 C4. I believe I stressed / ripped the CV boots during the install on the fronts. I ended buying some very good used half shafts to correct the problem. I'm not aware of any adaptors......I'm thinking since the wheel center point and halfshaft locations are the same you don't adaptors.

I've been running lower than you for over 5 years on my original 125k cv joints and no issues. Is it possible that you or previous owner ran over something before to cause this? Also, what do you mean by "failure mode"? Just because it leaks grease doesn't mean the joints themselves are bad. Have you checked to make sure nothing is touching your rotors like a stuck stone or bent brake heat shield? Are you sure the grinding noise is in the back and not front? Steering would have nothing to do with your CV joints since you have a RWD. Could be a bad wheel bearing.

Most likely its a age problem and you dont say how many miles are on the car or year. but its 10+ yrs old.

Buy some grease and new boots.

Quotes source posts: 13281558, 13281558, 13281558, 13281558, 13281700

Could be possible! I can understand that he did not want te tell me when he sold it to me Well, considering the amount of grease it spitted out and the grinding noise it is making I don't think that is normal. Could be that they are still okay and can be revised. A closer inspection by my Indy is in progress. Yes, I went first instance to the shop that installed the new suspension. It was the first thing they verified. Yes it is definitely coming from behind me. The grinding is also causing a vibration which I do not feel at all in the steering wheel. Steering is sharp as a knife in fact. The fact that the grinding noise is only occurring with serious cornering could also indicate a problem in the differential. Wheel bearings are also on the check list of my indy, but I don't think they are bad. Yes, certainly that is a factor! 2002 996 Carrera with 97k miles My indy is looking at it. He ran the car and after two corners he told me it sounds like CV joints. Also on the other side he could detect some anomality. I will know more tomorrow

Silk; I picked up on your statement: ... firm ride with souplesse. ... I'm au fait with the word souplesse given my fr-Cdn background but relative to what? 11 and 12 clicks out of how many in total? Ie, are you in the middle of band in order to get street driving 'souplesse', while being firm during cornering? Very curious as I need to do something with my suspension and undecided what to do.

Quotes source post: 13282422

Not too much experience yet. Did not have the time to experiment with different settings. They go from 0 to 20 (hard to softer). The suspension was set up by an authorised Ohlins shop. They have dialed them in for me to give me (according to them) the most balanced street setting (the outcome was the 11clicks front an 12 rear). I only have driven this setting so far. So no feedback yet on a harder trackable setting. When installing they revised the front arms with powerflex bushings because the rubbers were cracked on the left side. So both left and right were modified. The car is really different. More stability in the curves. Much better feedback. As far as my first impressions go the suspension in this setting is noticeably firmer compared to stock but ride comfort is pretty good. I dare even to say better. So far so good. I need much more time to be able to make a more objective review. After all I went from the original shocks to brand new ones. So it is difficult to compare. Also be aware that not every click represents a linear increase/decrease in damping characteristic. Ohlins itself indicates to use 0-2 as the hardest setting, not to go much lower. Same goes for the softer end of the range. They told me that probably for track use I will end up with something in the range of 5-8 clicks depending upon personal preference and driving style. The car is now on a set of yokohama ad08r (f:235/40/18 r:295/30/18) after aligning and weighing the car they were fairly impressed about the combo during test drive. I was looking into the Bilstein b6 b8 and pss10. But I took the plunge without any prior test driving to go for something less 'common'. What was a key factor in deciding was the one-way adjustability. Not too many parameters too look after. But still flexibility to go firmer or softer without any effort.

Short update: my indy confirmed the theory of the joints being not working as should. He is going to check the clearances in both longitudinal and rotational direction for the inner and outer joints both left and right side. Further all the suspension connections will be rechecked again. This analysis will further decide if re-greasing and new boots will suffice or replacement of the joints is necessary. I am thinking to change also the differential oil and the tiptronic transmission oil. That means I will have a clear maintenance reference point. As I changed over the last months already fluids and filters, ims, bigger water pump, low temp. thermostat, adapted cooling, x51 oil pan, modified AOS, braided stainless steel brake lines, suspension, tires. 25k miles ago the previous owner had the engine resleeved with nickies incl. a new crankshaft etc.

Interesting. I haven't personally ever witnessed a grinding noise as you describe from CV joints. They usually click or clack. If you've seen the joint past the boots, you can see how grinding would be rare, especially only making the noise on sharp turns as you stated. Either way hope you get it sorted out. I don't think you'll need to do the IMS if you already got Nickies in there, unless you subscribe to the strict maintenance interval, including time.

Ok maybe grinding is not precisely the right description of the noise. It is a combination of grinding with knocking which gradually builds up and disappears depending on load. The knocking comes up with sharp accelerated cornering, especially when starting from slow speeds. This is a typical heavy load scenario for the joints. Combined with the fact that I just lowered the car a bit it is for me to much coincidence. Also that a lot of grease get out at the same time the knocking started. I am wondering how much dirt made it into the joint. Maybe the joints already worn out before due to moist, dirt etc. and the new neutral position after lowering caused it to wear out faster. Another possibility is the shaft and joints do not have enough longitudinal clearance when it is under load. Hence causing a vibrating counter movement It could also be the differential off course as in sharp turning the differential starts to compensate for rotation speed difference between inner and outer wheels. No idea how that would sound. I have no time, nor the tools and detailed knowledge about how to diagnose it. I will have to rely on my indy for this. But I understand some of the mechanical aspects that are in play here. Thanks a lot for the input from all of you! Much appreciated The IMS is already replaced with an OEM version from SKF. I know, it is not the safest option. Maybe I will change it later for an improved ceramic bearing. Right now I will let it inspect evere 15-20k miles as good as it can. I have also installed a magnetic drain plug and spin on oil filter adapter and I am changing oil 2 times per year as I am running +15k miles per year. For the rest fingers crossed.

Quotes source post: 13284048

I really don't understand the logic to go through all the hassle and expense of getting Nickies and then just replace with a SKF OEM equivalent? Was this the black one advertised on ebay a few months ago by chance?

Quotes source post: 13285221

Thanks for your considerations! I did not go through the hassle of resleeving the engine. The previous owner did. But thanks again for your kind concerns. It was replaced and I am looking to a more solid upgrade as soon as I know what. Here in Europe the IMS solutions are not so common yet. The ims failures are scarce on the forums here. We see more scored bores and related failures.

Quotes source post: 13285389

Yeah I meant the previous owner's mindset.

Quotes source post: 13285484

Thanks for clarifying!

I have had the x-74 on my 2000 c2 for 30k+ mi. With no prob. Whatso ever.

I made a mistake above. The transmission mount was not replaced as stated in my opening post. The motor mounts were instead. Should have done the transmission mount too at the same time as it seems to be the culprit. CV joints, boots and drive shafts are in tiptop condition after detailed inspection. Differential ok. Wheel bearings in good condition. The transmission mount was shot. My mechanic says he is sure now it is the mount who caused the vibration and knocking. As he could somehow simulate it (at lower frequency). So it should be a cheap and easy fix. A coincidence that it started together somehow with the newly installed suspension setup which made the diagnostic procedure more complex than necessary. After all, the posts I referred to were indeed giving a good lead.

Quotes source post: 13297642

Still trying to comprehend how you can have a "grinding" noise as you described it from a worn/failed transmission mount. Also trying to figure out where the "grease" came from if your CV boots are in tip top condition. Only the engine mounts have fluid in them. Do you have a pic or did the mechanic give back your old tranny mount by chance?

Yes I understand your doubts. Maybe the noise does not qualify as grinding. I made some recordings with my phone pointed to the back. One video is a roundabout : short right turn followed by a round left turn. The other video is a left turn at a traffic light, followed by a long 180 degree turn up left. The noise is in reality much louder. click for video here I spoke to my mechanic on the phone yesterday. He first dismounted both shafts left and right and all the CV joints were okay, flexing and moving smooth. He said he could simulate the knocking noise by manually shaking the transmission when he jacked it up slightly, and that there was a lot of clearance that should not be there. Also the fact that both motor mounts were crap and changed some months ago he blames himself a little bit not to have tested the transmission mount to such an extent as now. The grease I found leaves me also in doubt. Could it be from when the new shocks were mounted they used grease for something in the suspension? Maybe it doesn't come from the car at all. All I know it was greasy and very sticky. I maybe wrongly suspected it to be joint grease. So I am not considering my diagnosis in the first post as bullet proof. The parts were ordered this yesterday, Installation was today or tomorrow. I will pick the car up tomorrow Thursday of on Friday. Maybe any further questions I should ask him? Your comments are much appreciated!

I've had grease leak out of CV joints with the boots seeming to be perfectly intact. Sometimes they do escape out of the boots occasionally. So this could still be a possibility. From the feedback from your mechanic, it sounds like it could be torn to me. "knocking" though rather than "grinding" would be more consistent of a failed mount. Do you by chance have a Tiptronic in your 996.2? Those can fail but I have yet to see the 996.1 or 996.2 manual mounts actually fail. I've seen "worn" mounts where they sag but not any that have torn personally. Once again, I'm talking about 996.1 and 996.2 NA manual trannies. I'd request the worn tranmission mount back from your mechanic just so you can see for yourself.

Quotes source post: 13299608

Yes I have a 2002 996 3.6 tiptronic. I will post pics of the mount as soon as i get there. Did you check out the two videos via the link to have an idea of the noise? The occasional release of grease could be related to the vibration going through the drive-train? Is it something to worry about? Could it be that the shot mount allowed the whole drive-train to flex to much outwards causing stress on the joints. I mean, as such the transmission shifting to the right a bit causing the clearance that the right shaft normally has to allow for the joint rotation with the suspension. Hmmm I hope you get what I mean.

Quotes source post: 13299685

Ah I knew it had to be a tip tranny mount. I think I know what you mean and I could see it as a possibility especially with swift transitions and high g loads. It would be interesting to see if both sides were torn or only one side.

Quotes source post: 13299685

Make sure your mechanic replace it with 997 tiptronic mount. Porsche changed the design to solve the mount issue with 997 part number. Mine was toast at 60K miles. 996.2 tiptronic mount is a known issue. It should take 1-2 hours to get it replaced.

Quotes source post: 13299879

check out the videos I made last week here See it simplified as follows (I will number the passages to make it easy to comment) A) the suspension makes the wheel center connection point translate up an down, an absolute vertical movement (yes very simplified). B) The outer end of the outer CV-joint can only move vertically up and down bue to rotation around the joint. Hence the clearance available in the shaft. C) To be able the outer joint end to slide horizontally back and forth when rotating around the joint under progressive loading of the suspension, i.e. in a curve under accelerating. Now here comes my wild theory 1. Taking in to account the lowering (less clearance available compared to original setup). The car sits lowr in its suspension. 2. The bad transmission mount causes: a) Considering turning left the engine tends to move right. Is it the same way the engine will move/rotate in the engine mounts when accelerating (loading the crank)? b) Then the bad mounts cause the whole drive-train under acceleration to shift too far to the left i.e. using up all horizontal clearance in the CV joint shaft. 3. Considering that the shaft doesn't have enough space to slide further horizontally upon further rotation around the CV joint (higher loads on the suspension). It will cause high loads on the shaft and makes it to bounce back at a max. threshold, after that forces load again, bounce back, loading, bounce, etc Hence causing a rhythmic knocking noise, also a little grinding audible. 4. This would mean a) excessive longitudinal loading on the CV joints. Which could maybe explain grease pressed out. and/or b) following this longitudinal forces the ***** in the joint start 'grinding' 'knocking' due to the high pressure and temperature (friction). The grease could seep through under pressure. I think my mechanic did not open up the boots to see if there are any traces of wear or frictional heating (yellowish/blueish/purple/black coloration of the steel). He just checked the boots and flexed/rotated the joints and found them to be in good shape. Wheel bearings were also fine. Maybe I am speculating to much. But the grease leaves me puzzled. That is however not the situation here. It is not a a swift transition that causes the noise to appear. The knocking appears after long persistent one way loading. In my case long sharp turning left with good acceleration, i.e. from standing still. It seems as a certain threshold of loading needs te be reached. It also stays there as long as the same acceleration is used. When lowering the load it seems to disappear only under a lighter load then it started, see it as a kind of hysteresis phenomenon if you would plot noise vs loading in a graph. It will appear under load A and get louder then lower again and dissappear under load B with B lower then A

As you can see in the photos the transmission mount was totally kaputttttt. Photos 2 and 3 are seen from the right; 4 and 5 from the left. On the right inner flange you could see a spot where metal has been rubbing over metal, scratched and burred. That was were the knocking noise came from. So no CV joint failure as in Title. Mount is replaced. Car drives smooth again!

Glad you got it sorted. The torn mounts is what I had pictured in my head. Hope you got the solid 997 replacements put in there.

Quotes source post: 13306094

Your tip to replace it with the 997 mount came too late. I need the car tomorrow for a DE. And there was no time to order the part for him. But the coincidence is that I ordered a couple of days before the mount started to knock already a set of sport bushings for the tiptronic mount from FVD. They are in back order. So we agreed the old mount will get the new bushings. And the new mount will be replaced.