worf928

Pilot Bearing
Release Arm Ball Cup Bushing
Repair Kit

I have no idea of the components included in this. Jim B?
From the price it sure as hell should have been everything.
PET does not know what this is.
Torque Tube

Jim B has cited the most common way to screw up a clutch job. That was one of my leading theories as well. If Jim knows what's in the 'repair kit' then we can make a final determination. However, it is possible that my next guess of failure mode is also possible (perhaps in addition to Jim B's) given this:
It is possible install and torque-down the clutch assembly without properly centering and seating the intermediate shaft in the pilot bearing. One of the last steps - if not THE last step - is to bolt together the intermediate shaft and torque tube shaft via a clamp sleeve. The ends of each shaft are machined to accept the pinch bolt that clamps the sleeve in place. If the intermediate shaft is not centered and inserted in the pilot bearing it is not very possible to use the original hardware to mate the intermediate shaft and torque tube shaft. And the perception in this case could be that the torque tube is "too long" since the intermediate shaft is 1/2" too far to the rear of the car.

However, I suppose that it is possible that an idiot could "put in non-spec bolts or spacer" and using a big hammer, drill, or blow torch put everything back together. If this was in fact the case that the uncentered intermediate shaft would allow the clutch disc itself to bind against the inside of the pressure plate and thus not return smoothly to the flywheel when hydraulic pressure is released to engage the clutch. I cannot image that a clutch put together in this manner would last for more than a few hundred revolutions or that it would do much more than vibrate horribly. However, it is easy to imaging that it would nuke the fingers of the pressure plate.


Thus this above barely-plausible theory would account for all the symptoms you have described:

- torque tube 'too long'
- clutch pedal only goes half-way back up
- pressure plate disfigured

Jim? Do you think any combination of non-spec parts and big hammers could be used to couple the i-shaft to the tt-shaft if the i-shaft isn't inserted into the pilot?

Jim bailey - 928 International

Dave I have seen shafts where a drill was used to "make" the clamping bolt "line up" that would be one way to have dimension issues. Another where the shaft was only partly pushed into the input shaft and the all time favorite was a broken input (one tab missing) that was WELDED to the driveshaft by reaching up through the small access hole That was precision welding ! Of course it meant the transmission and driveshaft can not be seperated !

ErnestSw

Dave,
A BFH can solve ANY problem!

docmirror

When the only tool you have is a hammer,,,,,,,,all problems become nails.

"Cheebuggah, cheebuggah, cheebuggah!! ---- Petsi,,,no Coke"

I was worried about that spacer, and non spec bolts too. Can the clutch plate be put in backwards on a 928? That might do it to. Happens all the time on many other cars.

Doc

worf928

The S4+ clutch disc has a 'tube' (for lack of the proper term) about 1" long on one side of the plate through which the intermediate shaft passes. With this 'tube' in place a reversed disc will not make contact with the flywheel.

So, yes, if you use a cutting apparatus and remove this 'tube' you can install the disc backwards.

worf928

Given what has so far passed on this thread, below is the theory on which I will place my bet:

The "repair kit" included a GTS-spec throw-out bearing. But, did not include the revised guide tube or release arm. The larger OD of the throw-out bearing allowed more-than-usual eccentric slop in the original smaller-ID guide tube and thus made it that much harder to insert the intermediate shaft properly into the pilot bearing. The original pinch bolt was stripped as a result of trying to screw it through the pinch sleeve with the intermediate shaft in the wrong position. A drill was used on the intermediate shaft to make a hole for a new pinch bolt of incorrect length purchased from the local hardware store. A spacer washer was used to keep the end of the too-long bolt from going wacka-wacka against the tube housing.

Anyone want to give me odds?

worf928

My secondary bet would be that since the clutch was done along with a new tube that - and thanks for this one Jim B - the tube shaft was welded to the transaxle input before it was fully inserted.

pepidcoe

Scary final thoughts... especially since this has all been dealer service! Anyone know of a local mechanic? Thanks for all your (collective) help. -- Pete

worf928

Pete, there are several shops of 928 repute in VA. I suggest that you start a new thread with a title similar to "Recommendations for a VA 928 shop."

There are undoubtedly folks who know about VA shops that have not followed this thread.

pepidcoe

Well. I picked up the car from the dealer and a mild vibration/noise started about 1 mile out. I drove it to another Porsche shop (12 miles away). They disassembled and reassemble parts of the clutch and were able to get the intermediate shaft seating it properly. The original 10mm bolt was installed in place of the makeshift 8mm bolt and nut in the coupler...

The car drove beautifully for about 320 miles (road trip to PA to pick up my daughter from grandparents). The clutch failed catastrophically on the way home, leaving parts of the lower bell housing on the road. Since this is the second failure in less than 400 miles, I am suspecting a parts mismatch / inept mechanics. The parts replaced initially were a master and slave cylinder. Have these changed? What kind of other damage could this type of failure provoke? Thanks. -- Pete

sportscarclassics

I have a 90 GT and it too has a drive line vibration at about 5000 RPM. New clutch job and the vibration appeared? Any ideas? Shifts well and works well below 5000 RPM.

Peter F

Pete,

sorry to hear about your misshap with the clutch.
I also have a 1990GT which currently has a noicy T/O bearing.
PO has replaced the clutch disc and T/O bearing less than a Year ago.
Not sure if the clutch arm or tube has been replaced before to the newer versions though.
Have now put the car in the garage to find out for sure what's in there.
(before anything more drastic happens, even more convinced this is right thing to do reading your story)
Have bought new T/O bearing, guide tube, pilot bearing and depending on whats in there will order a new clutch arm as well.
Seems like if you have an S4 without knowing exactly what has been replaced before it is very easy to go wrong.
Scary that a Porsche garage can't tell the difference though.

Cheers/Peter

worf928

The parts were probably already damaged prior to the last shop's ministrations.

Did the second shop not inspect the parts? Did they not verify the correct part numbers for the t/o-bearing, guide tube, and release arm? Did they not check the rear coupling through the inspection hole? Did you tell them to do these things?

Vilhuer

Perfectly normal universally it seems.

Daniel Dudley

My local Porsche dealer's technicians were in diapers when the 928 came out. They are in the business of servicing new cars so that people will buy new cars, so it is not in their best interest to keep the old ones in service. I have learned the hard way that it is worth finding a 928 specialist who is well known and respected. Take the time to find that person now, before you have anything else done. A well sorted 928 is a joy to own. If this is your principal issue with this car I'm sure it can be easily rectified. I have had jobs done two or three times by so called specialists, when in reality I only needed one good mechanic. Hang in there. It will all be simple to the right person.