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Sudden Clutch Failure?

T

tref

PCGB Member
Member
A strange occurrence yesterday... I pulled up at a set of traffic lights, lights changed, No drive. No warning signs, no previous slipping, no noises, all gears feel to engage the same, but no drive in any gear. I have now had a look under the back of the car, all drive shafts seem intact, and the one other thing I though could produce these symptoms, the connector between eth torque tube and gearbox appears intact (and both shafts turn together. This last fact is I think the give-away that something is up at the clutch end - the shaft should normally be connected to the engine (via the clutch) and it turns freely. The engine starts ok, so I am assuming the clutch outer is all ok and intact, but now I can hear a slight "shushing" noise with gears engaged, clutch up, and engine running. Has anyone experienced such a sudden failure before without warning? Any other ideas? I am wondering if the hydraulics have somehow "jammed disengaged", but the clutch pedal feels as it normally does. I did find the original wax on the sleeve that joins the torque-tube to gearbox, which would suggest the clutch is unlikely to have been changed ever - it certainly hasn't in the 200k+ miles I have covered, so I guess it has an excuse...

Any comments, ideas, suggestions welcome!

Tref.
 
Hi Tref,
Weird not to have had any warning signs of impending failure, but as you say the clutch pedal operation feels normal and the torque tube shaft is turning with the gearbox - (and turning freely with the clutch pedal up and box in neutral), it sounds like sudden total failure of the clutch driven plate. If it's the rubber-centred plate that would be very odd, as you'd expect to get plenty of pre-failure weirdness. I guess if it's really at 200k+miles anything's possible. Sounds like you're going to be busy!
... Further thought. Could the centre plate have jammed on the splines in a position that stops the pressure plate engaging? Maybe try pushing the clutch right down and letting it fly closed - slip foot off so it bangs shut on the centre plate. (Never seen this, just trying to imagine potential mechanical scenarios.)
 
Thanks Steve... The saving grace is that the clutch is one of those things I bought a while ago at the "right price" because I thought it would come in handy if I never used it... Seems I might!

 
Oh, and given the factory wax on the gearbox to torque tube sleeve, I reckon it has most likely done in excess of 360k, 'tis only the last 200k under my ownership, in which time I know for a fact it hasn't had a clutch! When I recently replaced the odometer gear, it appears that it had already been replaced once - so gawd knows how many miles the car might have covered previously without odometer - It skipped 1750 miles in the short time before I replaced it.

 
Tref, I'd go back to the dealer who supplied the car?

360,000 miles isn't normal for a clutch on a 944 and they should replace it for you. :ROFLMAO:

And nowdays they can't make an engine last 40K miles! :rolleyes:
 
As for the clutch jamming in disengaged position - one way for that to happen is for the release bearing to hang up on the guide tube which keeps the pressure plate from returning to the "clamped" position. I had sticky clutch and noisy bearing probs with my S2 so proceeded to have the clutch replaced even tho it measured with lots of disk left. Shop found nearly new disk/pressure plate but the release bearing was FULL of rock hard grease (appeared to be wheel bearing grease). This caused the bearing to stick on the guide tube New disk/pressure plate/bearing and guide tube solved the problems although in hind sight I should have replaced the clutch fork also as labor is the big cost for this job so do it all while you are in there.
 
There is actually an awful lot of oil under the car... I am wondering if I had a rear main seal catastrophic failure if that could cause a sudden lack of drive so... Though thinking about it, I would expect it to smoke and smell - neither of those symptoms made themselves apparent. I think you are right though... I should take it back to Porsche... Though I have a feeling I am going to be finding just a couple of springs, a few rivets and a hub rather than anything recognisable as a clutch plate!
 
bmnelsc said:
As for the clutch jamming in disengaged position - one way for that to happen is for the release bearing to hang up on the guide tube which keeps the pressure plate from returning to the "clamped" position. I had sticky clutch and noisy bearing probs with my S2 so proceeded to have the clutch replaced even tho it measured with lots of disk left. Shop found nearly new disk/pressure plate but the release bearing was FULL of rock hard grease (appeared to be wheel bearing grease). This caused the bearing to stick on the guide tube New disk/pressure plate/bearing and guide tube solved the problems although in hind sight I should have replaced the clutch fork also as labor is the big cost for this job so do it all while you are in there.
Click to expand...
So you had the clutch jam disengaged? Interesting... Did the clutch pedal feel normal, or did it stay on the floor?
 
I had a pool of oil under my car and the clutch wouldn't return to normal position after being pushed down. Turned out the clutch slave cylinder had failed completely and the master cylinder was also leaking.
 
OK, I had none of those symptoms... I have also just sheared the head off the bolt that connects the gear linkage rod to the gearbox linkage... Ouch... That is going to be a fun one to rectify - anyone else had that experience?

 
I doubt if this is it, Tref, but many years ago I had sudden clutch failure on a 924 Turbo, although symptom was clutch pedal went to the floor and stayed there. This turned out to be a broken clutch release fork (through age, I suppose). So ‘clutch/pressure plate, release bearing/fork, while you’re in there’ job.

As I say, it’s probably not this, considering the amount of oil you have noticed as well [:(]
 
There is a man on tipec that has just had the same thing happen, the centre of the friction plate has just sheared out
 
There is a man on tipec that has just had the same thing happen, the centre of the friction plate has just sheared out
 
Thank you folks - that would explain the symptoms I have. Encouraging that I am heading in the right direction. Have spent pretty much the day trying to separate the gear shift rod from the linkage at the back... finally got it separated, and box to torque-tube bolts undone - but I think all of this looks like it is the first time it has been touched in 26 years/360k+ miles, still tell-tale yellow wax on the torque tube to gearbox sleeve bolts.
 
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