elgy

I have and intermittent problem with the clutch chattering (juddering?… what is the word?). When it happens it is pretty bad, the car shudders rather badly. I have found I can get moving by giving the car more gas and slipping the clutch until it is under way. Usually the next time I stop and pull away the problem is gone or there is a very small amount of chattering. The last time I experienced a similar symptom was with a Ford Pinto that had a broken clutch plate. I understand that oil on the clutch friction material might also cause this.

The clutch was rebuilt a few years ago and I have done less than 5000 kilometers since. Most of my driving is around town and normally the clutch works well, although sometimes, again intermittently, there is a very small amount of chatter during engagement, barely noticeable and not at all bothersome. This new problem has occurred on 2 weekends on trips out of town after doing 100 or more kilometers on a freeway. The last time I experienced this was this morning and it was typical. I arrived in town after about 2 hours on the freeway. Did between 5 and 10 stops with no problem, then it happened… once. Next stop and go no problem and I got home after several more stop and goes without incident.

I am wondering if there is a bit of an oil leak somewhere and continuous high speed driving causes an accumulation on the clutch plate which gets wiped off after a start or two. I inspected the bottom of the bell housing and no oil is visible, so there is not a serious oil leak.

Any other ideas? Thanks in advance.

elgy

Bump...

marc abrams

Difficult to say without being there. My old Daytona turbo Z did what you are describing. It was a bad set of ignition wires.

boisenelson

It's really hard to give any specific diagnosis over the internet without being able to put eyes on the situation. I don't know what fluid could leak on on the clutch disk/pressure plate on a 924, but a couple of things to check our might be:

Bent diaphragm fingers of the clutch pressure plate
Resonance in the drive train
Rust on the pressure plate

These are some things I would check out myself and since I don't have hands-on experience with the 924 and you haven't had much feedback on your post I thought I would at least provide you my thoughts on where to check. Good luck and I hope you get the issue sorted.

elgy

After another day of driving I remain mystified. My suggestion that the shuddering only occurred after freeway driving was proven wrong... it happened again before I got out of town. I got the impression that it is perhaps in the drivetrain other than the clutch because when the extreme shuddering starts I depress the clutch and it seems that the shudder continues a split second longer, as if, for instance, the transmission was bouncing around on worn out mounts. I convinced myself that this was the problem. I had a look at the tranny mounts and though the rubber inside the mounts is lifting a little at the extremities they look solid and the transmission can't be moved by hand. I then placed my iPhone in video mode under the transmission, put on the hand brake, started the engine and eased the clutch out. No vibration or shuddering and when I reviewed the video the transmission was rock solid... no movement at all. The motor mounts were changed about 6 years ago but I inspected them during the winter and they appear fine and the engine is solid at idle, not bucking around like it was with the old mounts.
I am going to continue to inspect the drive train and accessories to see if anything is loose or broken, but for me the symptom seems to point to the clutch. I really don't want to do all the work necessary to inspect it until I have eliminated all other possibilities.

elgy

Thanks for the suggestions. The car has been driven enough that I am sure the rust on the pressure plate is not the problem. The problem is so intermittent that I think that the release components are likely OK... there has been no change in clutch feel, movement or sound. As mentioned in another post I am looking at the rest of the drive train in case it is resonance or something broken or loose.

elgy

After trying to convince myself that the problem is something other than the clutch, i.e. something easy to get to and easy to fix, I am accepting that I will have to dig into the clutch. I think it is the clutch disk that is broken... friction material ripped away from the rivets maybe? I have started to look at prices and I don't see any reasonably priced disks. I will tear it apart before ordering, but am curious if there is some one that sells disks at a price that doesn't approach the price of a full kit.

curtisr

It may be that the replacement clutch was still a rubber one (which can deteriorate with time). Try this: put car in neutral, remove access rubber viewing cover where the torque tube meets the transmission (number 4 in the diagram) and try to turn the drive-shaft (number 2). If it turns (1/8th? 40 degrees???) and stops with a clunk, it may be the clutch. I just went/am going through this (same juddering usually in 2nd gear). Really, really hope this helps.

elgy

It's not a rubber center clutch... I replaced the broken original clutch plate with a spring center unit in 2013. I am not looking forward to doing it again, but it should be easier given that the bolts have only had 5 years to rust rather than 26 years the first time around!
The problem only manifests itself while moving off from a stop, during the clutch engagement.

Constantine

Hi Grant,

Symptoms also present as problems with the front pilot bearing to front drive shaft end nub fit being too loose. This is usually caused by the end nub of the drive shaft getting worn down and not holding the drive shaft securely within the pilot bearing and clutch.

Could also be a problem with the torque tube front bearing either coming apart or migrating rearward and not holding the drive shaft correctly at the front.

Both conditions will cause damage to the clutch and drive shaft if not taken care of soon.

HTH and good luck with the search!

Dan Martinic

elgy

I bit the bullet and am on my way to getting my eyes on the clutch, yesterday the exhaust came off and I got the transaxle out. By tomorrow I hope to get the torque tube pulled back and the clutch exposed...
It is going a lot faster than the last time (which was also the first time) that I did this! Partly due to experience and mostly due to not having to deal with nuts and bolts that have had 27 years to corrode into place.

Dan Martinic

ecostellodo

elgy

Well, that took a week longer than I had counted on... I finally got the clutch out today. What is curious is that I didn't find any problem. As mentioned earlier then clutch has done about 5,000 Km since changing the plate, the fork shaft and bearings, the throwout bearing and some other little bits.
- the clutch plate is fine
- the pressure plate nice and smooth, nothing broken,
- throw out bearing turns smoothly no sign of wear
- the flywheel is nice and smooth
- the drive shaft turns smoothly and no sign of looseness in the torque tube bearings.
- pilot bearing seems fine also

Pressure plate



The flywheel, there is some staining, not rust... the surface is smooth


The 2 sides of the clutch plate... no broken springs or other anomoly.



So I started looking elsewhere in the drive train. I had visually inspected the transmission mounts and didn't see any degradation, but now out of the car I pulled on the metal part that mounts to the car and the rubber was separated. In this picture you can see about a half-inch of rubber sticking out on the left side.


Si I pulled a bit more and it totally separated with not a great effort. So could this be the problem? The transmission bouncing around on its mounts when starting from a stop? I am not convinced, but this is the only obvious problem. The rust on the inside indicates that the separation has been happening for a long time.