IMS Bearings...the Full Story, Awesome Job LN Engineering!

[M.D. Holloway]

IMS Bearing - The Full Story | Oregon Region Porsche Club of America

A close friend sent me this (thanks Torbin) and I found it very interesting. I guess it should go to the tech board but I look here more...

LN Engineering hit a home run here!

Question - does the 996TT have a single row? I was always under the impression the 996TT didn't have these issues.

[RedBaron]

Originally Posted by M.D. Holloway

IMS Bearing - The Full Story | Oregon Region Porsche Club of America

A close friend sent me this (thanks Torbin) and I found it very interesting. I guess it should go to the tech board but I look here more...

LN Engineering hit a home run here!

Question - does the 996TT have a single row? I was always under the impression the 996TT didn't have these issues.

996 TT does not have an IMS as it uses the old metzger block from the 993 and has a dry sump system. Interesting article; thanks for sharing!

[M.D. Holloway]

see that's what I thought! I should have bet my friend a beer!!!

[KNS]

Originally Posted by RedBaron

996 TT does not have an IMS as it uses the old metzger block from the 993 and has a dry sump system. Interesting article; thanks for sharing!

It has the IMS, all Mezgers do. The IMS and its bearing found in the M96 engine is just a different (inferior) design.

[onewhippedpuppy]

None of that is anything new. Jake Raby and LN are a great technical resource, but never forget that they make money off of IMS fears. They have a very vested interest in making you worry. They also did a nice job of dis-crediting the competing product (oil fed retrofit bearing) without any actual data. Which is my biggest problem with the entire debate - there is zero test data to back up anyone's claims.

[djmcmath]

Originally Posted by onewhippedpuppy

None of that is anything new. Jake Raby and LN are a great technical resource, but never forget that they make money off of IMS fears. They have a very vested interest in making you worry. They also did a nice job of dis-crediting the competing product (oil fed retrofit bearing) without any actual data. Which is my biggest problem with the entire debate - there is zero test data to back up anyone's claims.

^^^ This. I'm a huge fan of data-driven decision making, and there's just so little real data to support any decision on the IMS problem. The only people who are really talking about proposed solutions stand to profit from my fear, so I have to assume bias. Jake Raby makes some really great stuff, true ... but do I really *need* his really great stuff?

[aschen]

will y'all remind me which regular NA 911s are completely immune from these failures (er nearly completely I mean).

It starts with the 997.2 911 and the 2009 cayman s where they have this problem mostly sorted?

[Deschodt]

Originally Posted by aschen

will y'all remind me which regular NA 911s are completely immune from these failures (er nearly completely I mean).

It starts with the 997.2 911 and the 2009 cayman s where they have this problem mostly sorted?

yes, completely sorted in fact on those models... 997.2 and 987.2 are immune.

M96 and M97 engines have the issue. The M97 less so. The new engine 9A1 that came out in 09 models has no intermediate shaft at all, so no IMS bearing, problem solved.
So anything up to a 1998 993 and anything after (and including) a 2009 model year 911 or boxster or cayman is safe in that respect (there are other things you may worry about if you want, such as DFI).

99-08 is the trouble zone, but it is a matter of degrees. M96 engined cars (98 or 99-04 deopending on where you live, commonly 986s and 996s but also some early 05 997s in some cases, the cutoff is fuzzy) have a troublesome bearing but *can* be retroffited with a new one (LN etc) at clutch change time for a couple grand. I've seen one such 997 with my own eyes, wish I'd bought it as they are substantially cheaper than 997.2s... In truth those replacement bearings themselves have not been out all that long so there is no long term data on them either ;-)

05-08s (997s / 987s) have a bigger bearing that cannot be retrofited without splitting the case because of its larger size, but supposedly fails less often (but still does occasionally).

The brit mags report that the S models are more prone to it (3.8 997). have not seen that mentioned as much on this side of the pond.

GT3s and Turbos are exempt from this hoopla on account of a different bottom end.
Still confused ?

[onewhippedpuppy]

To confuse it more, the 1999 and early 2000 996 had a double row bearing that has more load carrying capacity and a much lower failure rate. The 1999 was exempt from the IMS bearing class action lawsuit. 986 Boxsters appear to have a much lower failure rate, it is frequently thought that having the same bottom end as the 996 but lower HP output does not stress the engine as much.

Worth noting, and hidden in that article - the LN Bearing is not a "lifetime" bearing. They warranty for between 50,000 and 60,000 miles. The failures of LN bearings I've usually seen attributed to foreign particles that were already present in the engine from a failing IMS, which is of course nearly impossible to refute.

As an engineer, what SHOULD happen is to test an original bearing in a similar environment to failure, test the LN product in an identical manner to failure, then compare the results. It wouldn't be difficult to set up, and I strongly question why they have not done so. Or maybe they have, but the results were not favorable?

[aschen]

Originally Posted by Deschodt

yes, completely sorted in fact on those models... 997.2 and 987.2 are immune.

M96 and M97 engines have the issue. The M97 less so. The new engine 9A1 that came out in 09 models has no intermediate shaft at all, so no IMS bearing, problem solved.
So anything up to a 1998 993 and anything after (and including) a 2009 model year 911 or boxster or cayman is safe in that respect (there are other things you may worry about if you want, such as DFI).

99-08 is the trouble zone, but it is a matter of degrees. M96 engined cars (98 or 99-04 deopending on where you live, commonly 986s and 996s but also some early 05 997s in some cases, the cutoff is fuzzy) have a troublesome bearing but *can* be retroffited with a new one (LN etc) at clutch change time for a couple grand. I've seen one such 997 with my own eyes, wish I'd bought it as they are substantially cheaper than 997.2s... In truth those replacement bearings themselves have not been out all that long so there is no long term data on them either ;-)

05-08s (997s / 987s) have a bigger bearing that cannot be retrofited without splitting the case because of its larger size, but supposedly fails less often (but still does occasionally).

The brit mags report that the S models are more prone to it (3.8 997). have not seen that mentioned as much on this side of the pond.

GT3s and Turbos are exempt from this hoopla on account of a different bottom end.
Still confused ?

Nope not a bit confused thanks to your useful summary

I

[Deschodt]

Originally Posted by onewhippedpuppy

To confuse it more, the 1999 and early 2000 996 had a double row bearing that has more load carrying capacity and a much lower failure rate.

All good points.... An agreed on (lack of) testing... My old SC's clutch lasted over 150K miles with many track days. Even if a 996/997 clutch wore faster due to more power (I sold mine before 60K miles so I never got near), seems to me even the replacement bearing would need servicing more often than my clutch !!! Sucks... I guess the "no-intermediate shaft-at all" solution is simpler ;-)

That's why I'm looking at xx7.2 models. Actually the new turbo Boxster is so pretty I cannot wait to see the new Cayman !!

[aschen]

Yeah I sort of wince when I hear upgrading the IMS bearing on one of the problematic cars is a sure bet. It might be true but im not sure there is enough data to tell that with engineering rigor.

[onewhippedpuppy]

Originally Posted by Deschodt

All good points.... An agreed on (lack of) testing... My old SC's clutch lasted over 150K miles with many track days. Even if a 996/997 clutch wore faster due to more power (I sold mine before 60K miles so I never got near), seems to me even the replacement bearing would need servicing more often than my clutch !!! Sucks... I guess the "no-intermediate shaft-at all" solution is simpler ;-)

That's why I'm looking at xx7.2 models. Actually the new turbo Boxster is so pretty I cannot wait to see the new Cayman !!

I've had multiple 996s with over 60k on the original clutch and still going strong. My last one had the clutch done at 95k. I had a Boxster that didn't need a clutch until 110k.

Originally Posted by aschen

Yeah I sort of wince when I hear upgrading the IMS bearing on one of the problematic cars is a sure bet. It might be true but im not sure there is enough data to tell that with engineering rigor.

There is zero engineering rigor, just lots of hype and anecdotal evidence. A few cars have cropped up with failed LN bearings, they are usually deflected with something along the lines of "Flat Six innovations didn't do the rebuild so it may have been wrong" or something like that. Jake is a smart guy and I believe does know his stuff on the M96/M97, but most of his "factual" statements are pretty damn self serving.

[jrj3rd]

Thought I read somewhere last year that Jake had continued to investigate this issue and believed it was not so much "bad design" as "bad execution" . Something about blocks that had failures had IMS alignment issues and all the ones that had been checked that were still going strong did not have the same alignment issue. He was supposedly working up some procedure to "check" for issues and was not going to recommend putting bearings in bad ones as they would more than likely suffer the same issues. My google-fu is off today and I can not find the original comments, but I am sure they were in a posting from Jake (maybe 986forum)

[M.D. Holloway]

KTM (Kevin) over in the technical thread sites "That intermediate shaft pictured at the top of the article doesn't belong there. That shaft assembly is the air-cooled (and 996TT, GT3) shaft assembly that has no relation to the M96, M97 water cooled engines."

Interesting catch...

[tcar]

Would one think that a 986 going 115k miles on the original clutch (highway miles) and no IMS failure that you had a good case with good alignment?

[Deschodt]

Originally Posted by Wayne at Pelican Parts

wrote:
>I recommend that the bearing be swapped out each time a clutch replacement is performed (30,000-45,000 miles). (in his great article)

You need a clutch every 30-45K miles ? I must be doing something right ;-)

[onewhippedpuppy]

I'm sure Wayne would love to sell you a clutch kit every 30k.

[M.D. Holloway]

Originally Posted by Wayne at Pelican Parts

I'm biased, but I like my article better:

Porsche 911 Carrera IMS Bearing Replacement - 996 (1998-2005) - 997 (2005-2012) - Pelican Parts Technical Article

-Wayne

no kissing up but I tend to agree...

[Jeff Alton]

Originally Posted by onewhippedpuppy

To confuse it more, the 1999 and early 2000 996 had a double row bearing that has more load carrying capacity and a much lower failure rate. The 1999 was exempt from the IMS bearing class action lawsuit. 986 Boxsters appear to have a much lower failure rate, it is frequently thought that having the same bottom end as the 996 but lower HP output does not stress the engine as much.

Worth noting, and hidden in that article - the LN Bearing is not a "lifetime" bearing. They warranty for between 50,000 and 60,000 miles. The failures of LN bearings I've usually seen attributed to foreign particles that were already present in the engine from a failing IMS, which is of course nearly impossible to refute.

As an engineer, what SHOULD happen is to test an original bearing in a similar environment to failure, test the LN product in an identical manner to failure, then compare the results. It wouldn't be difficult to set up, and I strongly question why they have not done so. Or maybe they have, but the results were not favorable?

This is one of the best posts about the IMSB issue I have read on the internet.

cheers