crushingday

I am getting a shuttering RPM dependent vibration rather badly and certain RPM"s are considerably worse Issue goes away when the clutch pedal is depressed. I understand I should: Find the RPM range where it is worse, look to see if my TT bearings have migrated. Check for a broken clamp.

It is not clear to me if it is coming from the front or the rear of the car. it seems to be all along the center under the car. Could motor mounts or transmission mounts cause this issue? What about clutch components although the two discs are relatively new. Could it be a finger on pressure plate? is it necessary to have the clamps taken somewhere to be spun on something to be sure they are perfectly balanced? if that is even a thing? or should they not have changed? Any thoughts on where to look is appreciated.

A few years a go I installed a rebuilt TT as I was getting two new clutch discs and had severe wear on the shaft splines. At that time I also replaced the front and rear shifter cup/couplers and am using Greg Brown's stub shaft.

P>S> I have modified this post and title and left Mark at 928 Intl. a message. I sincerely apologize that my first post was disparaging

FredR

Are you sure it is the bearings?

Bearings tend to squeal - that you use the term "clunk" suggests it could be the damper that has come loose? Does this happen when you accelerate/break or is it continuous?

crushingday

Well I guess "clunk isn't the right descriptor. It shakes and the shaking is more pronounced at certain RPM's. I have edited my original post to clarify and remove the word "clunk" with "vibrate". It all goes away if I depress the clutch pedal. Smooth sailing through the RPM range if the clutch pedal is pressed.

FredR

You might do well to check the front coupling hasn't cracked.

Are the vibes more pronounced at 1400 and 2800 RPMS by any chance?

Zirconocene

I always recommend @Michael Benno 's nice write up on replacing TT bearings: https://benno928.wordpress.com/2022/...e-torque-tube/

Someday I'll have enough of my own fires put out to be able to do this myself, not from need, but from desire.

That said, reach out to Mark Anderson directly, as well, I'm sure he'll be able to help.

Good luck

ROG100

Have you talked to Mark out of courtesy. I am sure he will help as best he can.
Sorry you are having an issue. I have sold plenty of Marks TT's in the past without issue.

brim32

Call RPR Automotive in Brooklyn Park,MD. They are a father son team that did mine, 1985 928S, installed super bearings and used the Ritech clamp from Roger. They are inside the beltway on Belle Grove Rd, IIRC. They’re located inside the beltway. Also replace shocks and coil overs in rear.

Good fellows that are honest, and tell you straight up what’s going on.
I’ve dealt with Colin, son and John is the pop.

crushingday

I will Drive it again briefly and see. Any tips on how to check this?
I will reach out to Mark

I will reach out to Mark and certainly correct and or or remove my post if the bearings are not the issue

thank you. I may have a friend help me with it locally but he has plenty of other things going on.

FredR

You can open the inspection cover on the bell housing and take a look in there.

Although possible that the TT bearings have gone south [again] I would think it somewhat unlikely unless something has excited premature failure.

Are the symptoms identical to the original failure you experienced thus causing you to believe the problem is the TT bearings again?

UKKid35

I would have left out the name of the vendor

Even from an enlightened self-interest point of view, it weakens your position significantly

icsamerica

A little quick on the trigger finger there. Before condemning the TT repair get it out and verify what failed. That said... Even if the repaired TT bearings did fail, I'd be satisfied with 7 years from a specialty remanufactured part that was made available to a niche market.

Mrmerlin

you can use a bore scope to figure out if the bearings are migrating,
thus you wont have to remove the bell housing,
and only the inspection plug at the rear.

Schocki

Replaced the TT in my GTS in 2005 at 100 kmiles with a rebuilt unit from Mark. No issues whatsoever, car is currently at 180 kmiles.
Give Mark a call first, he has been supporting the 928 community for years.

crushingday

The rebuilt torque tube was due to worn splines and not a bearing failure issue when i replaced it

Yes in hind sight i have should have done just that. My apologies to 928 International and Mark personally

Agreed I will do further research and pin point the issue

thanks Stan

Yes I know Mark has been a trusted vendor and supporter.


I just left Mark a message. How do I delete this thread?

Schocki

Write a message to an admin, they'll take care of your request.