Palmbeacher

Please don't feel sorry for those of us who own '05 997's. The 997 garnered a lot of demand in its first year, and by dealer accounts it sold very well. There are probably a lot more '05's around than '03-'04 together. These cars are now going on 6 years old, and if IMS failure were truly rampant, the internet would be rife with accounts. In-warranty replacement is not an explanation. You merely need look on other forums (not even car-related), to see clearly that the fact something is still under warranty and repairs are done at no cost to the owner is not a deterrent to people reporting their experiences! And in this country it's nothing short of ignorant to assert that mass failures of engines in such an iconic brand would not be found newsworthy, in this day and age of media outlets grabbing at any and every story they possibly think has an ounce of sensation. Somewhere, someplace there would've been a TV spot or newspaper piece on it. As is, if you go through all the internet fora, you can probably find no more than a couple hundred verifiable first-hand accounts of IMS failure. Allowing that there are ten times that many cases in actuality, that would be a couple thousand cars...out of every M96-engined Porsche manufactured between MY99 and MY08.

Here in Florida there are tons of Porsches on the road 365 days/yr. Speaking with owners (and mechanics) wherever I find them (parking lots, the dealership, independent shops, PCA meets...even stopped at red lights) I have yet to speak to a 997, 996, or Boxster/Cayman owner who has had an IMS failure-related engine breakdown. Speaking with a couple of shops who have done the LN retrofit, they have said the OEM bearing in every case was found to be in perfect condition. I can only go with my gut, in believing that my odds of suffering an IMS failure on my '05 are much less than those of having it totaled in a collision, or stolen. For the latter cases, I carry insurance. For IMS failure, along with all other mechanical breakdown potential scenarios, I carry an extended warranty. At the point I need a clutch, I have no objection to having the LN retrofit installed. By that time there may actually have been enough of them in actual use that we might have an idea if they live up to their promised reliability.

Palmbeacher

Please don't feel sorry for those of us who own '05 997's. The 997 garnered a lot of demand in its first year, and by dealer accounts it sold very well. There are probably a lot more '05's around than '03-'04 together. These cars are now going on 6 years old, and if IMS failure were truly rampant, the internet would be rife with accounts. In-warranty replacement is not an explanation. You merely need look on other forums (not even car-related), to see clearly that the fact something is still under warranty and repairs are done at no cost to the owner is not a deterrent to people reporting their experiences! And in this country it's nothing short of ignorant to assert that mass failures of engines in such an iconic brand would not be found newsworthy, in this day and age of media outlets grabbing at any and every story they possibly think has an ounce of sensation. Somewhere, someplace there would've been a TV spot or newspaper piece on it. As is, if you go through all the internet fora, you can probably find no more than a couple hundred verifiable first-hand accounts of IMS failure. Allowing that there are ten times that many cases in actuality, that would be a couple thousand cars...out of every M96-engined Porsche manufactured between MY99 and MY08.

Here in Florida there are tons of Porsches on the road 365 days/yr. Speaking with owners (and mechanics) wherever I find them (parking lots, the dealership, independent shops, PCA meets...even stopped at red lights, I have yet to speak to a 997, 996, or Boxster/Cayman owner who has had an IMS failure-related engine breakdown. Speaking with a couple of shops who have done the LN retrofit, they have said the OEM bearing in every case was found to be in perfect condition. I can only go with my gut, in believing that my odds of suffering an IMS failure on my '05 are much less than those of having it totaled in a collision, or stolen. For the latter cases, I carry insurance. For IMS failure, along with all other mechanical breakdown potential scenarios, I carry an extended warranty. At the point I need a clutch, I have no objection to having the LN retrofit installed. By that time there may actually have been enough of them in actual use that we might have an idea if they live up to their promised reliability.

cbzzoom

Palmbeacher, the people you are talking to have more extensive first hand experience with this problem than anyone in the world. I believe most of us on this forum would like to hear what they have to say and learn from it. Show some respect.

I certainly hope you guys will come up with some solution for the 997.1 engine. Our bearing may last longer than the M96 but it seems like will still be a failure point long term, and I'm interested in whatever can be done to make the engine more durable.

Charles Navarro

Depends on what you call catastrophic. You can have an IMS failure where the bearing can be swapped out on the MY97-05 engines as long as it is caught early. A completely failed bearing destroys the housing, requiring the engine to be completely torn down to replace the shaft as part of a complete overhaul. Both will result in a repaired engine, but at greatly different prices.

No, not true. The shaft itself is going the same RPM, but you have a larger diameter bearing in the MY06-08 cars, which results in a slower outer race velocity due to higher circumference, but same RPM. The smaller diameter bearing has a higher outer race velocity.

Some of what you state is spot on and actually discussed (or implied). I think you need to re-read what we have written. Great care has been taken to look at the many things that contribute to the problem, greatest of all being that a ball bearing shouldn't have been used here. Even though I'm not an engineer, I'm married to one and have spent a great amount of time discussing this and researching it myself. (I didn't get to know everything I know on lubrication by having a degree in Tribology). A pressure-lubricated plain bearing as used on previous intermediate shafts should have been retained during the re-design.

EHL lubrication of the ball bearing and film strength required to provide adequate protection of the ball bearing is another factor, just as more frequent oil changes.

Oil changes themselves won't help until the seal itself has been compromised. At that point, the seal is more of a hindrance, preventing adequate flow of oil to the bearing, only allowing whatever oil is trapped by the seal or in the ims itself to lubricate the bearing. More often oil changes at this point ensure the oil trapped in the IMS is of better quality than fuel laden, acid rich oil found in long drain intervals or vehicles with severe duty cycles (short drives, etc.) where fuel intrusion or high moisture content comes into play.

My point exactly. Tracked cars do tend to have less problems, both due to higher rpm use (not being abused) and more frequent oil changes. But taking a car that has 10,000 miles in 10 years then tracking it now, doesn't mean it won't fail. The damage is likely already done.

Many of the earlier retrofits as well as full upgrades, including those we did our testing on, were conventional bearings, exposed only to engine oil. The choice to go to ceramics were definitely an attempt to make this a permanent fix and address some of the ball issues associated with the conventional ball bearings and their particular failure methods.

There are lots of things Porsche designed that are far from right. We are left to pick up the pieces. We just have to work within those constraints and make the most of what we are given. Waiting and hoping for Porsche to goodwill a failure or extend a warranty is a pipe dream.

Charles Navarro

I tried to explain this to you on the phone, but I don't think you understand the Porsche world, how Porsche regards its customers (and products out of warranty), and the average Porsche owner. Most aren't looking to sensationalize this and go to media outlets. Most don't go on the internet nor have ever heard of this problem. Dealerships propagating that there aren't problems further isolate these failures from one another. If one was to think it never happens and just happened to them, that it was just bad luck. If Porsche goodwills even a small portion, they are usually more than happy and will sing the praises of Porsche, even having had a failure in the first place.

Trust me, I spend hours on the phone with people (like I did with you), everyday.

There have been some instances, like in Canada, that got press (and we received calls), but nothing ever comes of it. Threats of class action lawsuits by those hit by the failure normally never pan out because Porsche legal has nearly limitless funds to defend against such lawsuits. Those customers with the money to sue Porsche would be those that would trade in the car and buy a new one, and chalk it up to bad luck. Those who want to sue, usually don't have the means to follow through.

http://www.girardgibbs.com/PorscheIM...Fctw5QodQDI_YQ

We offer a solution to a known and well documented problem. The likelihood of a failure is probably not that great, but that's no consolation to those who have experienced a failure and the associated 15-20k bill for the repair. Everyone is free to come to their own conclusion on what or what not to do. Before even trying to sell anything, we try to explain what to look for and how to hopefully extend the life of the existing bearing.

Treating the original bearing like a preventative maintenance item, as many have done (and that's why a good percentage of the bearings are in good shape when extracted), is to be proactive. Including the procedure at the same time as a flange reseal, clutch, or RMS makes the most sense, considering that most of the labor is shared with such a job, and makes the most financial sense.

But there are some cases (ultra-low mileage cars or those poorly maintained) that may warrant early action due to the statistical probability of those cars being most suspect for failure.

Palmbeacher

Thank you for your thoughtful response. It is both gratifying and builds confidence in your product. As I have said previously, if my engine has not "grenaded" (and been replaced under extended warranty) by the time I'm due for a clutch, I would not hesitate to have your retrofit installed at that time. There is only one point you made I'm not clear on:


If as you say the outer race has to travel a greater distance (circumference) in the same time (rpm), then wouldn't it need to travel at a faster velocity? Think about it. You're in a car going on a circular track along the outside, which is 1 mile in circumference. Your friend is in a car going around the inside of the track which is 1/2 mile. You each have to make one revolution around the track in one minute (rpm). To do that you (a single point on the larger-diameter bearing) need to travel 1 mile per minute (60mph), he (a single point on the smaller-diameter bearing) needs to travel only 1/2 mile per minute (30 mph).


We have never spoken on the 'phone, although I would enjoy doing so someday.

Charles Navarro

Yup, spot on. I'm the one that got mixed up here. Yes, the larger bearing would indeed have higher race velocity but same RPMs. Glad one of us is paying attention :-) I'll have to re-read my research as to why the larger bearing was considered a step in the wrong direction, but if memory serves me (which it typically doesn't), one of the other problems with the larger bearing was due to the larger rotational mass of the heavier ***** and corresponding loading/unloading of the bearing and resulting skidding/sliding of the ball. This is where the lubrication requirements (higher rpm requiring less oil film) come into play.

Like you stated, it isn't any one thing alone that causes these failures, but a multitude of smaller problems that can coalesce in the form of a full blown IMS failure.

Oh, and my apologies, I had this same conversation with someone from Florida earlier this week and was on the phone several hours. Felt like deja-vu :-)

I wish I had more time, I'd start making a gallery of all the used bearings I have along with corresponding data. Maybe that will be my winter project, since track season is over for us. That would help with the when aspect of doing the retrofit outside of a clutch replacement.

Palmbeacher

Absolutely. Enlarging the bearing (assuming it has larger *****, not just more of the same size) is not an unfounded way of beefing it up, but the tradeoff is that the stress of any imbalance or wobble will be magnified due to the greater mass rotating at greater distance from the center. A better solution (which you have taken) is to keep the bearing size unchanged, but use materials with greater wear-resistance.

A splendid idea! As you undoubtedly know, the economics of doing the retrofit are drastically different if the car needs a clutch or if it doesn't. I have a feeling that it will be a daunting if not impossible task to accurately predict though, due to the number of variables. I've seen at least one Porsche authority, I think in England, postulate that one factor may be the original installation of the OEM bearing, vis-a-vis tolerances of fit. They mentioned that they found some bearings fit unusually tightly, and the races showed evidence of metallurgic transformation (discoloration due to heat buildup). To me that's been the only hypothesis that fits with the wide range of mileage at which these bearings fail...some as early as <5K and others lasting well over 100K. While not arguing that it's a poor design, if that were the only factor, then we should expect not only a much greater number of failures, but that they would occur within a much narrower range of mileage (allowing for a few outliers of course).

Charles Navarro

I can even back that hypothesis up with photos of bearings sent back to us from retrofit installations, showing how some bearings show physical wear on the o.d. (outside diameter) of the bearing's outer race, where others look perfect, with varying levels of apparent movement.

It was Flat 6 Innovations that actually picked up on this and let me know, having done so many of them allowed them to start noticing the differences between bearings being extracted.

Likewise, some bearings come out easy where others come out without effort. Some even show no press, requiring re-installation with bearing mount to even get the replacement bearing in! There appears to be a great tolerance in manufacturing of the intermediate shaft itself and definitely this could indeed affect bearing life.

For the record, all three bearings shown felt good and had zero debris under the seal and I only found one ball in each bearing with very slight pitting. All three bearings had zero grease and the one with the worst outside appearance definitely had a burnt smell to it.

chago996

"I'm sorry but that's simply not true. Are you actually an engineer??? The bearing rotates at the same speed as the shaft, which is a fractional function of engine speed. The bearing could be as large as the earth in diameter and it would still turn at exactly the same rpm as a bearing the diameter of the shaft itself...or smaller, if that were possible."

Not an engineer but I think you are incorrect on this statement. The shaft speed may be the same, but if the ball bearings are farther away on the radius, they have to travel faster to reach the same point after 1 revolution in order to finish that revolution at the exact point in time compared to a smaller bearing.
Speed=distance/time. The distance around the circumference is longer, the time is the same, therefore speed is higher.

Charles Navarro

Palmbeacher had corrected himself on that statement and actually caught my typo on race velocity.

Indeed, the larger bearing will have a faster outer race velocity, but the downside is the ***** themselves weigh significantly more, amplify lubrication requirements, and increase centripetal forces acting on the bearing (flat spotting of the ***** and skidding through loading and unloading of the *****). There is more to this, but without pulling out all the papers and sitting down with a pot of coffee, my brain isn't up to the challenge :-)