Screeching Clutch

[godotwait]

I've been plagued by screeching clutches on my 2001 Carrera 2, 3.4 litre. It's just starting happening again FOR THE THIRD TIME!

Each clutch replacement goes for around 10k miles then starts to give a little screech as the clutch is released about 50% of the time.

Anybody any idea what's causing this?

[Rockster]

godotwait said:

I've been plagued by screeching clutches on my 2001 Carrera 2, 3.4 litre. It's just starting happening again FOR THE THIRD TIME!

Each clutch replacement goes for around 10k miles then starts to give a little screech as the clutch is released about 50% of the time.

Anybody any idea what's causing this?

Could be the signs of a failing release bearing. My only release (throwout) bearing failure occurred in another brand of car and the thing started screeching out of the blue when I pushed the clutch pedal down and continued to screech until I released the clutch pedal. Speaking of blue, the old throwout bearing was blue/purple from the heat.

Or it could be from something amiss with the clutch friction disc. I've been told when the clutch disc wears to the point the rivets contact the flywheel/pressure plate the clutch can develop a judder/shudder but makes no noise. However, there could be exceptions.

Or could be a squeak in the clutch pedal linkage/hardware. Both of my cars have make a small squeak whenever the clutch pedal is pushed in even if the engine is not running.

Needless to say there's a big difference between addressing a noisy/squeaky clutch pedal linkage/hardware vs. dropping the tranny to address (or at any rate eliminate) some other possible cause for the noise.

Have the linkage looked at and possible given a shot of lube of some kind. When my Porsche clutch pedal hardware/linkage makes a tiny bit of a squeak this is what I have done. Quiets the noise right away.

[godotwait]

Thanks for the suggestions which prompt me to add two further observations about the problem

1. The screech is so loud form outside the car that people look round. Which suggests to me that its probably too loud to be friction in the linkage.
2. I had the thrust bearings changed along with the clutch plate on each occasion, because I too thought it the most likely culprit. I still think it is, but I can't imagine 3 thrust bearings doing this in 10k miles each, unless there's something else amiss.

Peter

[Trev450]

Did you have the same brand of clutch/release bearing fitted each time? The reason I ask is I had a similar problem on a 350Z from new, and after 3 replacement bearings failed I had an aftermarket one fitted and the problem never reoccured.

[Rockster]

godotwait said:

Thanks for the suggestions which prompt me to add two further observations about the problem

1. The screech is so loud form outside the car that people look round. Which suggests to me that its probably too loud to be friction in the linkage.
2. I had the thrust bearings changed along with the clutch plate on each occasion, because I too thought it the most likely culprit. I still think it is, but I can't imagine 3 thrust bearings doing this in 10k miles each, unless there's something else amiss.

Peter

If the noise is loud enough people outside are looking at the car then I agree it is not the linkage.

A bearing can fail at any time. I could accept the 1st replacement failing and attribute it to a defective bearing.

For 3 bearings to fail out of the box -- well, within 10K miles (when they can last as is the case in my Boxster nearly 275K miles -- is unlikely to be bad bearings, unless the shop has a stock of cheesy bearings it it trying to work its way through. I would think the cost of absorbing -- I hope the shop is not charging you for these subsequent bearing jobs -- doing the job over would prompt the shop to trash the bearings rather than play against the odds and keep using them.

Assuming the bearings are not bad -- but I can't dismiss this out of hand -- there could be something else wrong but I'm hard pressed to come up with something.

A clutch can bind on the input shaft splines if the engine/transmission is not aligned properly. This binding could shorten a bearing's life, but at the cost of shortening the clutch disc's spline life as well of that of the input shaft and its splines.

If this were happening in the case of your car I think you'd know it by now from having the input shaft splines wear to the point the clutch disc would rattle, at least, or to the point the shaft would have to be replaced.

However, it would be I think worth it to inspect the engine mounts along with the transmission mounts to ensure none have failed and if the engine/transmission are not misaligned all the time they are not able to go in and out of misalignment while the car is underway.

Another possible problem could be the clutch hardware linkage is misadjusted and is causing the bearing to be pushed too much against the spring fingers of the pressure plate. If there is no adjustment perhaps the wrong slave cylinder rod is being used? Or the wrong slave cylinder if the rod it not a separate item.

I do not have my references handy but IIRC there is the possibility of an installation error. IIRC the bearing is installed to the fingers of the clutch spring. It does not reside totally outside of these but is held captive. If I'm right the bearing could be installed incorrectly and while it would work it would be subjected to more pressure from the extra effort caused by its being installed incorrectly. The effect would be similar to that of having the linkage misadjusted and thus forcing the clutch springs to be pushed more than is necessary to effect a full disengagement of the clutch.

When you brought the car back the 1st time after just 10K miles of bearing life the I would think the shop would do a thorough investigation to eliminate any other possible cause of premature bearing failure.

Which prompts me to ask what does the shop have to say about this? It can't tell you they all do that. Well, it could I guess but...

Maybe you need to consult with another shop?

[Bennachie]

Flywheel centre bearing/spigot bearing? rather than the release bearing.

[godotwait]

Thank you Rockster for taking the time to give me a very extensive reply.

I didn't take up the recurring failure with the garage that did the work (same one on each occasion), but I certainly will now. I was already thinking some kind of misalignment might be the cause. I will discuss this with them, but I am also inclined to take the problem to a different shop. Maybe even a Porsche dealer this time (I've been using an independent). I'm getting heartily sick of this problem - really the only one I've ever had with this car in 8 years of ownership. I came from a Griff which let me down at every opportunity…………...