cgrupp81

Friends, I purchased a highly recommended replacement for the main driveshaft support bearing mount from Pelican Parts, made by a company European Part Solutions. Pelican Parts part number is 955-421-020-15-EPS. The part was professionally installed on my 2006 Cayenne S a little over month ago by a reputable independent Porsche repair shop in Seattle. I was finally able to take a highway trip last weekend with it, but now very concerned that this part may not be the true solution for replacing the driveshaft support. There is a noticeable vibration when driving between 40 and 50 MPH which happens every time accelerating up to hwy speed and dropping down from hwy speed. I am wondering if the part is either defective or is not a true solution. Or maybe a bearing? Are there any of you that have made the same repair with this part and experiencing the same thing? (I have contacted Pelican also regarding this problem and awaiting a reply.) Thanks for any help sent my way.

Petza914

Either the driveshaft isn't balanced correctly or not aligned correctly. I believe there's a special alignment tool that the dealers use.

These types of issues are exactly the reason than on my 09 TTS I removed the inferior jointed Porsche design and replaced it with a heavier duty aluminum straight driveshaft. No center bearing support. Once and done.

slavie

What was your original problem before you installed the aftermarket bearing support? How was it diagnosed? In other words, why did you bother replacing it in the first place?

From what I've read and understand, though the bearing support is the most common failure point that results in the "little elves hammering in my transmission tunnel" sound, it's not the only component that can fail. The giubo (the rubber donut), the bearing itself, and the CV joints within the driveshaft can fail, too. And yes, the bearing support needs to be centered in the tunnel as Petza mentioned.

Hence, I'm planning to replace the whole driveshaft with aftermarket GKN 28054 when the time comes, which costs around $400. GKN is the OE supplier to VW, so chances are good it's same quality as original.

oldskewel

I installed that same part in my 2004 S a year or so ago, to repair the common problem of the center bearing support failing (rubber tears).

It worked perfectly well for me, but I will say that I took things slowly and was careful to align it. I did not use any special tools for alignment, but I did install it loosely, carefully let it find its natural position after shaking it around, tighten it, test drive, and re-check, etc. These simple steps may be beyond what some pro mechanics are willing to do - many aim for absolute top speed in parts swapping.

In addition to being careful about that, I looked for other potential misalignments, noticed that the transmission mount was partially collapsed, so I reinforced that with some fuel hose, as I reported here:
https://rennlist.com/forums/cayenne-...l#post16207155

I also inspected and repacked the bearing.

As far as I could see, there is not anything that could possibly be wrong with the EPS part. It could be due to insufficiently careful installation or some other problem.

A very simple experiment / fix you could do is to get under there and loosen the bolts holding the EPS bracket in place. Shake it around, let it find its natural center, then torque down the bolts while carefully not letting things move. Hopefully that will be in a different spot from before. Then test drive and see if anything changed. If there is no change at all, keep thinking, but if it got better or worse, this is a strong clue that more careful alignment is the issue.

BTW, I did not install a new giubo (also guibo), mostly because I did not have one to install. Mine visually looked fine. Theory is that the hardening of the giubo puts more stress on the original bearing support, leading to its failure. So that's why EPS and others recommend replacing the giubo as well, and why they include it in their kit. I can believe all that, but from looking at the thin rubber original bearing support vs. the new EPS one (or even the Jimi Fix), the retrofits are so much stronger that I can't see them ever failing. The other thing is that by not replacing the giubo, I did not have to touch it, which means I did not have a chance to misalign it.

reachme

I used the EPS part and it has worked flawlessly since, no banging at any speed.
If you are having issues then I agree there is likely a balancing issue though I did not run into it