Symptoms are: shuddering when clutch is depressed, and an annoying vibration when slowing down with engine braking, ie foot not on gas, gear selected and clutch up.

Tranny, TT and clutch were out for renovation before this and I guess I failed atleast the clutch assembly due the shuddering. The clutch disk looked almost new though. I'm wondering if the rolling vibration can be caused by the clutch also or is it something else? Car doesn't vibrate with gear in and clutch down so I don't think it's the CV's?

 

How are your engine mounts? Mine did something like this when the mounts were bad. The engine can rest on the cross member when the mounts are really bad, but some time before they are THAT bad the engine can touch the cross member intermittently..... like under engine braking or heavy accelleration, only there's too much other racket to notice it under heavy accel.

 

The mounts are also new anchor units, there can be an installation issue with them ofcourse, but the engine is definitely sitting high enough not to touch the crossmember.

 

Did you replace the pilot bearing?

 

Yes, had to use some force to get it in though.

 

Hi Aatos,

Did you solve your problem, or has it developed / changed ?

I am about to replace my mounts, as the engine is sitting low and does not rotate around its axis, when i dab the throttle from the engine compartment.

I have shudders when in reverse, as if the transmission is loose. When it is in reverse, and i slowly release the clutch at idle speed, it shudders, but if i release it at around 1200 RPM it is smoother, but nothing to brag about though.

 

Hi Ragnar,
Replace your MM's with solid ones and be very carefull with Anchor as they do not differentiate between solid and liquid filled.
Change your transmission mounts as well.
Roger

 

Ragnar,

Also, check the clutch arm pivot point on the bellhousing. My plastic bushing split and the pieces fell out causing some shudder when starting in 1st gear. The arm would pivot at a different angle then what it was designed for. Another DFW lister, who shall remain nameless, left the top two bolts out of the bell housing, allowing just enough flex to cause shuddering. Replaced the bolts and all was good!

Jim Mayzurk
93 GTS 5-spd

 

Don't forget about the torque tube..Chris F had an annoying vibration on his 928..ended up the bearing had migrated back and the front part of the tube wasn't supported like it should have been....replace the TT and all was good.

later,
Tom
89GT

 

Jim,

I have heard of the bushing, but unable to locate it in the PET. Maybe i didnt spend enough time searching for it, but do you happen to have some more details on top of your head ?

In addition to the vibrations / shuddering ihave the squeaky sound when i press the clutch pedal. Not fully depressed, but just resting my foot on the pedal.

Anyway, the Engine Mounts are the first step, then i intended to take a look at the bushing, and third a look at the transmission support.

I have had the TT worn bearings on a S4, that i owned a couple of years ago, and these vibrations are different.


Ragnar

 

The clutch arm pivot bushing is on the second page of the clutch diagrams in PET #8
P/N # 928 116 145 03

 

What exactly was done and/or replaced when the clutch was 'renovated?'

Was the throw-out bearing (release bearing) replaced?

 

Earl,

Thanks - the thing is now on my list to order. I'm certain it needs replacement.


Ragnar

 

Nope, the vibration is still there. I just received parts from 928intl and the next step will be to drop the clutch again.

Things to do:
1) Measure the torque tube axle front end to see if it's bent.
2) Have flywheel and pressure plate measured and if needed resurfaced.
3) Replace pilot and release bearings (w/ arm, guide tube and bushing).

 

Clutch work over. We decided not to resurface flywheel as it looked good, the TT shaft was not bent either. Car shifts mostly fine now without shudders, but the vibrations are still there on acceleration and engine braking.

The old release arm was worn, and t/o bearing rings were in bad shape, even though the bearing itself didn't look bad.

bent:


missing locking slot:


bonus pic of vilhuer polishing his car for concours: