EPS IMS Bearing Upgrade Kit

[wogin]

I just put the EPS roller bearing in a month ago. After researching this issue to death I ended up deciding to put this particular bearing in based on the following:

1) Roller bearing has a higher radial of load capacity than a ball bearing. I read estimates that the failure rate of single row ball bearings is as high as 10% before 100k miles but that the double row bearings had failure rates closer to 1-2%. The dual row bearing has more balls to distribute the radio load. This results in lower cyclic contact stresses in the balls and the races. In fatigue failure, even small decreases in stresses can dramatically increase the average time to failure of a part. A roller bearing distributes its load along the line of contact rather than a point. This design feature means that roller bearings will see much lower cyclic stress levels than a ball bearing of the same form factor. I chose a roller bearing over dual row ball bearing because I believe the cyclic stress level will be lower in the roller bearing than in a dual row bearing.
2) In reviewing pictures of the of the Boxster‘s engine’s internals, and the support configuration for the intermediate shaft, I did not see any sources of significant thrust load on the shaft. Given the lack of thrust loading, I concluded that the EPS bearings thrust washers would probably be sufficient to manage a inertial thrust loads.
3) I called EPS and spoke with them, and although they have not sold as many Bearings as The alternative suppliers on the market, they have not had a single reported failure. On the other hand I have read about failures on ball bearing retrofits (and The manufacture simply blamed installation rather than Entertaining the possibility that they supplied a defective product..)
4) cost. The EPS bearing was cheaper than a ceramic ball bearing retrofit, and the manufacturer claims it will last the life of the engine. Contrast that to the ceramic ball bearing that costs more and should be replaced every 40k miles. If I had all the money in the world to throw at this problem I would buy the Journal bearing retrofit kit, but for me it was just crazy to drop $1.7k on a 10% chance my $6k engine would blow up.
4) the speed of the ims shaft is compatible with the rated speed of a roller bearing of this size.

Finally, if I had a dual row bearing already in my car from the factory... I probably would have just left it alone... 2% failure rate isn’t high enough to justify the expense and hassle of replacing the bearing.

Please excuse typos. I wrote this on my phone and dictated some of it to Siri... she doesn’t hear me well sometimes.

Not looking to debate what solution is best, just throwing out the reason I made the choice I did in case it helps others with this decision.

[Gelbster]

Thanks for sharing your thoughtful analysis.
Having chosen the roller bearing option, why EPS and not RND ?
Roller Bearing IMS Retrofit Kit – RND Engines

[wogin]

Originally Posted by Gelbster

Thanks for sharing your thoughtful analysis.
Having chosen the roller bearing option, why EPS and not RND ?
Roller Bearing IMS Retrofit Kit – RND Engines

Actually did compare those two bearings. Although the thrust loads on the roller bearing should be very low. The EPS bearing seemed to me to have a better way of controlling those thrust loads. On the EPS bearing the thrust loads are transferred between the outside of the External race and the retaining washer faces on either side of the bearing. This ensures the ends of the rollers will not be the primary wearing surface. In the RND bearing appears to be an off the shelf rollerbearing that is simply axial retained by rigidly connecting its internal race to the cover/flange. Thrust loads would be between the roller ends and the internal edges of the bearing race... effectively loading the off the shelf bearing in a way that it is not designed to be. .... while this may be technically acceptable if the thrust loads are low enough, I just didn’t want to risk it. EPS seemed like a better thought out design.

[dsallean]

Originally Posted by Gelbster

Thanks for sharing your thoughtful analysis.
Having chosen the roller bearing option, why EPS and not RND ?
Roller Bearing IMS Retrofit Kit – RND Engines

Gelbster I know your question was directed at Wogin and his detailed post but I will add that when I was considering replacement of my IMS I searched the interwebs and I read everything I could find and came to my own personal preference for the roller bearing option. I was leaning toward the EPS version but the oiling system modifications kept me from pulling the trigger. It just didn't compute to punch a hole. It just nagged at me. So when RND came out with theirs and no oiling system requirements I pretty much knew that was the way I was going to go.

I really was in no hurry to replace my dual row IMSB and it ultimately came out in excellent condition. The replacement was accelerated after my Indy said the IMS was toast and I needed an engine replacement. Turned out it was a variocam puking green O-ring bits and the plastic variocam pads were worn. It was time for a new clutch and DM flywheel anyway

Dave
2001S

[paulofto]

Originally Posted by dsallean

The replacement was accelerated after my Indy said the IMS was toast and I needed an engine replacement. Turned out it was a variocam puking green O-ring bits and the plastic variocam pads were worn. It was time for a new clutch and DM flywheel anyway

Remember rule #1 with any Boxster or 911 from 1997 to 2004. If anything is wrong with your car, I mean anything, it is the fault of a failing IMS bearing. Period.