Re: Was it here that someone mentioned a version of the LN bearing failing?

Greetings,

I will be doing a clutch replacement on my '98 5 speed with 107k. I am looking into replacing the IMS bearing and have questions regarding the puller that Pelican and LN sell.

1) Is it necessary to do the job?

2) If so, are there any do-it-yourselfers out there that will rent or sell me one? I am a longtime 356 Registry and PCA member and will do right by anyone that can help with that, it just seems that almost $200 for a one time use tool (in my case, at least) is a bit much, so if you have one just laying around.....

Also, Pelican sells a factory IMS bearing with a stronger outer seal. My original bearing has made it to 107k so the Pelican part seems fine by me vs. the LN part, unless anyone has heard anything adverse about the bearing from Pelican.

I posted this on another site yesterday with no response, sorry about the cross posting but I would like to order the parts today or tomorrow.


Any help greatly appreciated.

Regards,

Sebastian



Edited 2 time(s). Last edit at 11/08/2012 10:04AM by SPG356. (view changes)

It is absolutely necessary, and makes the job a piece of cake. I would loan you mine, but I'm overseas, and will be for a while. If all else fails, you could buy one, use it and sell it to recoup some of it.
As far as the upgraded bearing, I used the LN, and was amazed at the difference. I wouldn't think you'd want to use the OEM design, since you're basically installing the same problem you're trying to fix. LN bearing is the way to go.

the bearing life is dependent on driving style. So is clutch life.

Given that his bearing has outlived his clutch it follows that there is no need for him to spend a lot more for a different IMS.

I think he will probably find the original bearing in very good shape but I'm eager to hear.

Quote
Boxsterra
the bearing life is dependent on driving style. So is clutch life.

Given that his bearing has outlived his clutch it follows that there is no need for him to spend a lot more for a different IMS.

I think he will probably find the original bearing in very good shape but I'm eager to hear.

That's a novel way to look at it. I've always considered this a one-time replacement, but I guess if you do it at every clutch change, you should be able to use OEM.

I changed my own, with LN, but I don't know if you can use an OEM without tearing the engine down. I thought that was one of the benefits to the LN model.

Now the LN is also unsubstantiated, but one look at the size and materials suggests that via brute force alone it will greatly outlast the original. Since i personally know 5 people who's IMSs failed, i would nto take a chance.

That said, i am apparently one of the people Boxsterra refers to. I did my IMS with the clutch and it was fine. All grease gone, but mechanically fine. My car is driven very, very hard, but also maintained very, very well (obsessively).

Get the LN. get the puller.

Grant (with tow boxsters that don't run at the moment)

Grant

gee-lenahan-at-gee-mail-dot-com

I said you could use OEM. What I should have added was,"why would you want to replace a part with known issues with the same part?" If you're going through the trouble to drop the tranny, you might as well go the safe route, with a presumably much more reliable part?

I beg to differ on the IMS/bearing life being dependent on drving style, so since it outlived the clutch, every thing is hunky dory. There is absolutely nothing to back up that statement. Cars have been tracked regularly with no issues, while my daily driver (2002 S) with only 10,001 miles lost its IMS on a roadtrip between DC and Chicago and three months after its first oil change. Other cars have lost their IMS before and after clutch replacements. There's no bearing what-so-ever on drivng style having and impact on the bearing. Mine broke down on a simple roadtrip between DC and Chicago (Toledo). I loved my car, but the sole reason I no longer have it is because Porsche finally designed the IMS out of the engine. I think that goes a long way in telling you that there was some big issue with the IMS. I don't know which model year we began to see a problem and why (different supplier, slight tweak to the design, etc), so your '98 could be fine, but Porsche has been tight lipped about the problems so there's no way to tell when the problem started and whether changes over the years decreased the issue until the IMS finally went the way of the Do Do Bird.

Agreed agreed agreed. The IMS is a dice roll. No clues, not patterns, no real knowledge. Only thing I have found, from reading the boards and talking to mechanics, is that it is not predictable.

Minus 40 degrees... Is that Fahrenheit or Celsius?

Of the 7,000 plus installed, they have heard of or received returns from 8 failures. Of those several were installed incorrectly, some failed because another engine part failure resulted in debris in the bearing and one had an unexplained cause failure. The single bearing cage was redesigned with new material in late '10 and there have been no failures of that part reported since. The double bearing part has no reported failures. (This was as of about 2 months ago and was direct from LN)

If I were doing the bearing, I'd pay to have someone who had done many before do it. If I were going to do it myself, I'd use the bearing that had the most installs, the best instructions and use the tools and techniques exactly as they recommend. I read of problems reported by those who are not doing it that way.

How reliable is this information? I've been keeping tabs on the prices of used Boxsters from 2009 to 2012. I'm thinking that perhaps I should also conside a 986 Boxster S and pay to have the LN bearing installed right after purchase.

I said that there is conclusive evidence that IMS failure is based on driving style. I did not say what type of driving causes the failure. We know that driving hard definitely does not cause failure. There are theories that the seal drying out from lack of use may contribute to failure, as may a lack of splash lubrication.

The correlation with driving style is based on mathematical analysis of what we know for sure and has been discussed here and elsewhere before.

1. Hard driving keeps the seal from drying
2. Hard driving results in splash lubrication
3. Blackstone labs reports much better UOA results from cars that are used on the track
4. Mine was among the better examples

So flog away. If you baby your car, be very, very frightened.

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

Thanks for all of the advice. I have ordered the parts along with the puller. I went with the Pelican factory bearing with the stronger seal.

I have put 67k of the 107k on the car and I bought it 4 years ago for $15,000. If it blows up now it still cost me less to drive than leasing a Ford Fusion.

I would love to drive it another couple of years and am prepared to do so.; I am also prepared to have a salvage company tow it away in case anything happens and I'll go out and buy another used one.

I'll take pics of the bearing when it is out and report back.

Regards,

Sebastian

Quote
SPG356
Thanks for all of the advice. I have ordered the parts along with the puller. I went with the Pelican factory bearing with the stronger seal.

OK, I have now waffled and will likely order the LN bearing tomorrow and send back the Pelican unit if it has already been shipped.

As was pointed out to me, the extra $450 for the LN bearing on top of a $2,000 + job is probably worth it no matter how long I keep the car.

Thanks again to all

to pull off the transmission every 4-5 years and inspect the LN bearing as is recommended. So don't just factor in $450 extra but an additional $1000 or so every several years.

I would argue there is compelling evidence that people who have driven over 100k in their Boxster and find through inspection that their IMS bearing has minimal play do not need to reinspect it regularly if they replace it with a stock part. Here's why:

I have never heard of anyone even suggest that the variation in bearing life from owner to owner is due to variations in manufacturing.
Similarly I've never heard anyone suggest that some single event causes failure.

It follows that if you put the same part in the same car and expose it to similar conditions, you will get roughly the same results, i.e. minimal wear over 100k miles and N years.

QED

and both recommend replacement/inspection...one at 40k or clutch change whichever comes first and one at 50-60k or 4-5 years. Each figure straight from their respective vendor's owner.

Neither do even the people who have worked to develop these kits claim to know exactly what combination of things leads to a higher probability of failure, they suspect...they surmise...they experiment...they test..they change in what seems to each a logical way. And then they monitor the results. If you know, I'm sure all of us would like to know the details of the data set you used to form your theory.

if you include the stock part, for which the manufacturer has no such recommendation.

It's true that nobody has identified definitively what the cause of failure is but based on my above comments it actually doesn't matter. And besides the recommendation to reinspect is based in large part on having no data about the specific part in the given conditions.

(For what it's worth, although it's not needed for my current argument I have previously explained mathematically why failures cannot be due either of the above factors)



Edited 2 time(s). Last edit at 11/11/2012 07:15AM by Boxsterra. (view changes)

So we are left with 2 commonly available replacements. (I know of perhaps 4 more but they aren't commonly available.)

Mike, as usual thanks for the detailed information.

I did not know when I bought my 08 that replacing the IMS would require the equivalent of an engine rebuild. As I see it, there are now 3 IMS Boxster groups. Those that can replace the IMS at a reasonable expense (1997-06), those that can replace the IMS as a very expensive proposition (06-08), and those that do not have to worry about the IMS anymore (09 and beyond). I can't say that I am unhappy with my 08, just the oppostie, I love the car, nor do I lose sleep over a potential IMS failure. I will drive it as if the IMS will never fail. Do I have another choice? I can't see replacing the IMS at what might be half the price of a replacement engine. If it destroys my engine, then it is probably better to get a rebuilt engine with LN IMS.

However, of the 3 IMS Boxster groups, I wonder if this additional IMS situation with the 06-08 Boxsters will effect their relative resale value.

1999 Arctic Sivler/black/black (sold)
2008s Silver/black/black - so predictable
2011 Outback
8/24/2011 first Grandson

OTOH, I have heard that the later IMS engines (2006-2008) have a much lower incidence of IMS problems.

the 987 motors, particularly the 3.4, are not having anywhere near the IMS failure rates that the 986s had.

I have no data. I have no theory, except that, according to a usually technically sound source, the IMS bearing in the 987 has a lot of the characteristics (size anyway) of the LN model. According to him, those motors are pretty solid (or as solid as an M96 motor can be).

Anyone know differently? Or have supporting evidence?

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

Quote
grant
the 987 motors, particularly the 3.4, are not having anywhere near the IMS failure rates that the 986s had.

I have no data. I have no theory, except that, according to a usually technically sound source, the IMS bearing in the 987 has a lot of the characteristics (size anyway) of the LN model. According to him, those motors are pretty solid (or as solid as an M96 motor can be).

Anyone know differently? Or have supporting evidence?

Grant

There have been a few 987s on the Planet 9 board that have reported IMS failures, but the first question that comes to mind is whether there was a post failure analysis of what happened by examination or it was just assumed the IMS failed.
I'm thinking if the IMS or a connecting rod/bolt fails, the end result will look pretty much the same--and who would want to spend good money trying to figure out the cause when there is no warranty coverage?

on the 3rd generation IMS bearings ('06-'08) that we haven't heard as much about them because they are new and early failures were handled under warranty and so owners tend not to seek to vent on the forums. So as they age we'll see better how well they fare. Having said that, those I've talked to say they are doing very much better than the gen 1 and 2 versions pre '06. How much of that is because other parts were improved along the way and aren't putting as much debris into the oil? Don't know that answer either. Just suspect there is a contributing factor.

... there is certainly a flaw in the IMS bearing design and/or the bearing itself.
To me, the proof of that is Porsche's redesigning the M96/M97 engines to do away with the IMS altogether.
The very first M96 engines (1997-1999 Boxsters and 1999 and 2000 Carreras) have the highest failure rates.
The 2000-2004 Boxsters 986 and Carreras 996 come next, followed by the 987 Boxsters and 987 Carreras and finally the 2nd generations of both platforms.
I see the IMS bearing (whether OEM or aftermarket) as a wear item which should be checked every time the transmission is down for clutch or RMS replacement or other, or every 100K miles or less.
Here's what I've learned from all this:
a) Porsche redesigned the IMS bearing several times, installing the upgraded bearings into the new engine versions. These improvements helped but did not solve the problem.
b) The newer the engine the less time it's had to fail. I've always said that the IMS bearing in an M96/M97 engine is like a man's prostate. Give it time... it WILL develop cancer.
c) The aftermarket solutions, although better than the OEM still have to be checked and/or replaced at the same schedule.
d) I have certainly seen that tracked cars do have longer-lasting IMS bearings than garage queens.
e) Since the bearings take time to catastrophically fail, Chip Detector Technology, such as the IMS Guardian, is my choice of early preventive warning.
Happy Boxstering,
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

---

Racecar spelled backwards is Racecar

"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"

"If you wait, all that happens is that you get older"... Mario Andretti

"Being second is to be the first of the ones who lose" ... Ayrton Senna

Pedro,

I wrote above that if my 987 IMS replacement requires an the equivalent of an engine tear-down and rebuild, cost-wise how would that compare with replacing the engine?

Or, to think about it another way -- Suppose I have the engine taken out and the IMS replaced every 100,000 miles. And, I do this twice at 100K and 200K, and the cost of each is half the cost of a new engine. Then if I am fortunate and my IMS lasts to 200,000 then at 200,000 I can have a new or rebuilt engine which is probably going to be better than my 200,000 mile engine with only the IMS replaced. How does that logic sound?

Thanks, Bob

... is different because of the nature of the redesign.
What I would do if owned a 987.2 engine is monitor the oil on a regular basis, cutting open and checking the oil filter every time.
If I worried constantly about the IMS bearing, then I'd install an IMS Guardian.
I also check for camshaft deviation when I do a 60K mile service regardless of the year.
Generally I don't see movement, but both times I've seen it, the IMS bearing was replaced and it had already started to deteriorate.
For manual cars that will have the clutch replaced at some time you can then physically check the IMS bearing for oil leaks and or movement.
Happy Boxstering,
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

---

Racecar spelled backwards is Racecar

"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"

"If you wait, all that happens is that you get older"... Mario Andretti

"Being second is to be the first of the ones who lose" ... Ayrton Senna

Both approaches are reasonable but it is unknowable which one is better for you because of randomness and the variation in risk tolerance between one person and another.

Imagine parts failing on a bell curve frequency and you not knowing, until they fail, where on the curve yours will fall. And not knowing the shape of that bell curve. That seems to bother you or you wouldn't be asking the questions you do ... it didn't me. Doesn't mean you are wrong or right, just that we have different attitudes towards risk and uncertainty.

Some people value not losing more than winning but then there are others who are just the opposite. You know yourself better than others...how will you feel if you do nothing and bad things happen ... can you just shrug your shoulders and move on or will you agonize over "coulda, woulda, shoulda"? OTOH, how will you feel if 2 days after you do the IMS you total the car? Or 6 months later your circumstances change and you sell it? Or 6 months later a new and improved model IMS kit becomes available?

(I ask these questions because I once again just sold a car I had updated for the long haul ... great tires, total brake system, rear hatch strut ... 3 weeks later ... sold. I could have saved by not doing any of that but life moves on and its beautiful today.)

Mike and Pedro,

All good points. One other idea that I'll throw in is that by the time my IMS blows, if it does (at 5K/yr it will be 17 years from now that I expect to hit 100K, and at 64, I'm less likely to be here than the car when I'm 81!), then mechanics might have worked out ways to install non-IMS engines. That will solve the problem permanently. For my daughter :-)

... driving it 5,000 miles per year, it qualifies as a garage queen and I wold check the parameters a lot more than one which gets driven regularly.
Happy Boxstering,
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

---

Racecar spelled backwards is Racecar

"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"

"If you wait, all that happens is that you get older"... Mario Andretti

"Being second is to be the first of the ones who lose" ... Ayrton Senna

What if its 5,000 hard miles a year, Pedro?

"A mile of highway will take you one mile. A mile of runway will take you anywhere."

Year around I try (snow and travel the exceptions) to drive my Box 2-3 times per week. Nice weather, longer drives. Nov-March still 2-3 times per week, but only enough to fully warm it up. Still, even on my short winter drives, after warm up, I hit 6 to 6.5K rpms at least twice. I figure if there is anything to the "washing" the IMS with oil theory, then that is when I am doing it. What I don't do, but did with my '99, was DE where I would be over 4K for long periods of time. I am not one to hold back on rpms. My "normal" shift is around 4k, my "normal" cruising is never under 2.5K, but for more spirited driving, like taking an exit ramp, I am quite comfortable downshifting to 2nd at 4K and accelerating through the turn. (That sure is fun and why I miss DE, but at my age, I did enough of that.)

the key factors are: 1. is moisture and acid driven out of the motor and the oil regularly 2. is sufficient splash lubrication provided to maintain bearing lubrication once the grease is expelled. 5000 miles can easily do that - i drive between 5-7500 annually and my car sees at least one 45 min x 2 commute, and lots of time in the higher rpm reaches. Oh, and when inspected looked good, and UOA says "excellent".

OTOH, a car that sees two 2500 mile highway cruises at 60 mph does not qualify.

Details, details.

Grant

Grant

gee-lenahan-at-gee-mail-dot-com