1995 GTS Manual: Noisy Flywheel

[Evremond]

Just had the central tube, clutch plate, pressure plate, clutch release bearing etc replaced by a very credible Porsche specialist.
However, there is now much more noise coming out from flywheel clutch area. The workshop explanation is that "over the years Porsche has modified and enhanced parts, compared to the originals, and a consequence is much more noise, which cannot be avoided or reduced". As a layman I find it hard to think that Porsche "enhancements" would result in a much noisier transmission, which to me is unacceptable.
Is this explanation plausible?

[Mrmerlin]

well we need more info about the noise and when it happens, is the pedal pushed or released ?
when the car is rolling or stopped?

If there is any noise I wouldnt drive it till you figure out what the noise is.
also please include a list all of the parts that were replaced.

Clutch operation should be quiet, with the pedal pushed or released.
there are too many possibilities for the noises till we know what exactly was done

[JK McDonald]

Hey Evremond, Like Merlin mentioned, a little more information may help to diagnose your problem.

1. By a credible Porsche garage - do you mean that they routinely work on the 928

2. Were you able to talk to the mechanic that actually performed the work about any installation problems

3. Is the noise completely new - or - just considerably louder than before the clutch work

4. Do the new clutch parts, shift linkage, etc.... perform properly

5. Does the noise sound like a growl, rumble, grinding, etc….

6. Do you primarily hear the noise when the clutch pedal is released or depressed

Just my opinion but the explanation the garage is giving you just doesn’t hold much water. There were a number of drive line improvements and updates over the life of the 928 which where all included on the 95 GTS model. If all the new parts were installed properly - (assuming you had any noise previously) should have decreased considerably over any worn components that had reached the end of their life.

Michael

[dcrasta]

New parts are not noisy. Sounds like the Credible Porsche shop lacks 928 Knowledge.

Your car with a new clutch should be quiet. (or minimal mechanical noises).

[Pete R]

If your old system was noisy maybe it's now quiet allowing you to hear something else . That's happened to me after I've fixed something..

[aluminum]

Never accept any Repair Job if It's not working right >>
If you did return it ASAP >
Something is messed up no doubt > like the disk in backwards ? BUT >>
Most likely the wrong parts installed .
Always compare and check all parts BEFORE installing them

[davetr]

or something was left loose

[Danglerb]

I remember one with a ticking sound, turned out a bolt was backing out and hitting the flywheel.

[Mrmerlin]

it could also be the shaft coupler pinch bolt hitting the bell housing
or area near the guide tube ...
OR the flywheel is hitting the slave pushrod
or the release arm bushing has failed and the TOB is not centered
or the pilot bearing has failed
or the TOB wasnt installed correctly,
or the disc was installed backwards,
or the wrong guide tube was used with the wrong TOB
or the wrong release arm was installed .........


Need more info about what was replaced

[Evremond]

As a first-time poster I am absolutely amazed at the very helpful and thoughtful responses. Sincere thanks to all.
As suggested, I will describe the symptoms in more detail tomorrow once I have tried the "clutch on/off," "rolling/stationary scenarios".
I will also copy out all the parts that were fitted.
The "credible" dealer is as experienced as anybody in the U.A.E. on 928s, but in that there are hardly any 928s here, the experience is understandably limited, and to date I haven't come across another manual GTS here.
The clutch was previously very stiff but the noise levels were low and seemed faraway. The noise now sounds raw and close.

Evremond
1995 928 GTS
2004 911 996 Turbo
2010 911 997 Turbo
1981 911 SC
2010 Cayenne Turbo S
2008 Boxster RS60

[Danglerb]

Could be they left out the big insulation pad around the shift lever on top of the torque tube.

[Evremond]

Thanks once again for all the searching questions. As suggested I herewith attach a better description of the noise and also a complete list of the parts which were fitted in the hope that it will allow us to home in on the cause.

I used the car today for the 45kms to work and it is performing beautifully once moving properly, it's just upon starting and then in 1st & 2nd in low revs that the noise is so much noisier than before.

Noise does not seem different to before, nor new, just much noisier. The slight metallic knocking which necessitated replacing the central tube has gone.

The clutch behaves smoothly and well. Much lighter than before.

Noise is same if stationary or rolling, although once at mid revs it is less noticeable, probably because of other noises.

Noise differs depending on if clutch is depressed or released, but is unacceptably noisy in both positions. When clutch is released in neutral there is an additional overlay of another plate whirring.

There has always been a metallic grinding flywheel noise in 1st & 2nd between 800- 2,000 rpm, which is still there. But again, it just seems noisier now.

The suggestion of having forgotten to put back the big insulation pad around the shift lever sounds very plausible. I will ask the mechanic specifically as my initial thought was that the reverberating louder noise sounded as if insulation was missing, but I was not aware of there being an insulation pad there. Maybe it had perished over the years and not having a new one to hand they did without.

Parts replaced:
Central tube; Oil Sump Gasket; Pressure Transmitter; Repair kit; Clutch plate; Pressure plate; Clutch release bearing; Pan-head screw x 2; Shaft seal; Connecting hose; Clutch operating cylinder; Clutch release lever; Guide Tube; Clip Shaft Drive; Grease Drive Shaft; ATF 111; various fluids and consumables.

Sincere thanks to all for all previous input and for any further thoughts please.
Evremond

[Mrmerlin]

looks like the pilot bearing isnt mentioned in the replaced parts list

[Danglerb]

Originally Posted by Danglerb

Could be they left out the big insulation pad around the shift lever on top of the torque tube.

Pelican Parts - Product Information: OEM-92855603306

[dcrasta]

Originally Posted by Mrmerlin

looks like the pilot bearing isnt mentioned in the replaced parts list

A lot of places dont replace that and they should. Some cars (not familiar with manual p-cars setup) can be awkward to remove. Likely they did not remove / lubricate the pilot bearing.

I would take it back and tell them they messed up .

[tmpusfugit]

since they changed out the torque tube I am thinking this is the part (sound insulation) that did nt get replaced, if this is really a lack of insulation problem versus a true mechanical problem

Pelican Parts - Product Information: OEM-92842418203

[Mrmerlin]

to figure out if the foam is missing,
roll down the window,
and drive the car at 35mph,
see if there is hot air coming up the shift boot.
If you dont feel any hot air then the foam is most likely in place

[Evremond]

Thanks for this further guidance.

Danglerb, Mrmerlin, I will do the 35mph test to establish if the insulation foam is in place and specifically discuss this with the mechanic tomorrow (today, Friday, is weekend here).

Also, Mrmerlin & Dcrasta, you are correct that the pilot bearing isn't referenced in the work card. What is the significance of the pilot bearing in this instance?

I'll report back on Sunday with the workshop's answers/ reactions.

[Sapientoni]

The 928 clutch is the easiest clutch in the world to replace. I would do them all day long for $500 labor + parts. The pilot bearing is a "support" item that is a little painful to replace, but it has to be done. It's only about a $10 part and industrials are available.
There's a little technic to the initial spacing of the double discs, but the "tools" must be fabbed and they're simple.

Good Luck and happy motoring. Sapientoni

[Evremond]

I tried the 35mph open window test and no hot air coming up gear shaft. Then went to remove the leather surround only to discover that the frame which clips it onto the base around the gear shift had not been clipped back. Clipped it back on tightly and most of the new unacceptable noise vanished; amazing how much sound insulation that provides

Checked with workshop who had lubricated the pilot bearing.

All in all it is now not much noisier than before the new parts were installed and in that it is going better I will live with things.

Many thanks for the helpful ideas, and apologies that the cause was a lot less technical than I had first assumed.

Evremond