Clutch, CVs or transaxle - help please!

[MrTibbs]

Hi folks,

I've recently bought a 1986 924s, which is in fairly good condition - had a lot of work done to it in 2003 (full respray in Maraschino red metallic, re-trimmed centres of the leather seats in a purple leather, 17 inch carrera replica wheels). However, it makes a clunking noise when accelerating or decelerating.

First thoughts, having looked at a few posts on this forum and others is that it's the clutch's rubber centre wearing out. However, I want to be sure it's this and not something else before I spend almost the purchase price of the car getting a new clutch.

I've got under the car and removed the rubber cap thing from the transaxle bellhousing and given the torque tube a good twist; with it in gear and with the clutch pedal up the TT twists a bit. It rotates around the same amount in neutral or 1st, and progressively less in higher gears until it's pretty still in 5th. When I rotate the TT it makes the clunk that I get when changing gear when it reaches as far as it's going to rotate.

I've also had a good pull at the CV joints; when moving the axle inboard or outboard (ie not trying to rotate it) it seems smooth, but I'm able to twist them a little bit with the wheels on the ground, and there's slight play if I try to move the trans end of the axles in a circular motion.

I've not had a chance to pull the starter to check for bits of rubber (though there weren't any when I pulled the rubber plug in the clutch bellhousing), and I've not been able to undo the filler plug on the transaxle to change the oil and see if that makes a difference.

So after all that, my question is, is it likely to be CV joints or the ring and pinion that's making the clunk from the back, or is it definitely the clutch? I should mention that the noise it makes really sounds like it's coming from the back of the car and not the clutch area - if the rubber centre's gone on the clutch I'd assume the noise would come from there?

To be more specific, what are the definitive tests I can do on the car to locate the problem. I can afford to get the clutch done, but I'm not the world's richest man and I'd like to fix what needs doing rather than things that don't.

Hopefully some of you guys can help - you seem very knowledgeable.

Thanks
Mike

[looneybin]

the rubber center clutch could be disintegrated & you are hearing the limp home tabs hitting.
But that noise would not be coming from the rear of the car

could also be excessive play in the ring & pinion, but not likely.

Check that the bolts to the CV & axle are good & tight, any looseness could cause noise under acceleration/deceleration.

BTW welcome to the board.
If you have not already done so, also check out Clark's Garage Home Page
There is a wealth of info there, and on this board as well

[smokin_944]

If the CV joint bolts are in tight (30lbs) and the sound isn't a clicking sound, move to the next choice cause it aint likely to be your CV joints. If the sound comes from the back of the car, it probably isn't the clutch either. The TT could be suspect, or mebbe the ring and pinion. That is what I will have to look at cause I have a similar problem but my problem is not linked in any way to acceleration or deceleration. Good luck and if you find the source of the problem please let me know. TIA

[Panzer909]

I'd suspect the CVs as well, but not too sure they make noises while DEcelerating as well(?) When mine was on its way out, it just did a few clunckclunkclunks from the starting line and that was it.

I agree that if it was the clutch, it would NOT be coming from the rear of the car. Are your CVs original as far as you know?


.......did you check your diff oil?

[porsche4life]

Whats the trans mount look like?

[MrTibbs]

Thanks for the help. I'll check the CVs are tight (was wondering what the correct torque woul dbe so thanks for that).

Not been able to crack open the trans filler and drain plugs yet (they're on tight!) but will get a bigger breaker bar.

To elaborate on the noise a bit more - when I got under the car, turning the torque tube made a clank when it got as far as it was going to go in either direction (noise seemed to come from in the trans somewhere. It also makes this noise when rotating one of the rear wheels if one side of the car's jacked up. with one side jacked I can rotate the rear wheel about 1/8 or 1.4 turn before it makes the sound and stops turning.

The experience of driving the car is that it feels as though there's some slack in the drivetrain. If I'm smooth with the clutch (and if I keep the revs high while I change into a higher gear) it doesn't make the noise. When pulling away from standstill you can feel it take up the slack. It does seem classic clutch failure symptoms but for the fact I'm sure the sound's coming from the back.

I don't think I'd get the noise from turning the TT with the car not running if it were the trans mount?

M

[porsche4life]

Sorry... No you wouldn't...

Sounds like you have TT troubles...

[Slam]

Try putting the car in 1st and then getting out and rocking it back and forth while listening. Or better yet, have your trusty assistant (whoever that may be) rock the car while you listen. It appears as if what you're hearing are in fact the limp home tabs on the clutch, but by rocking the whole car you should be able to reproduce and pinpoint the clunk. This happened to my 924 and this is how I diagnosed it.

[kdjones2000]

With the clutch pedal UP you should have NO movement of the driveshaft in the TT. Doesn't matter whether or not the transaxle is in gear or not.

Your rubber center on the clutch disk is dead, allowing the driveshaft to rotate.

If you want to verify more, pull the stater and look for rubber debris in the opening.

Good luck, Keith

[MrTibbs]

Thanks for the help guys. I suspected the clutch from the outset - was really just being optimistic it was something else. Had the clutch replaced at a local Porsche specialist. Cost a lot but the clunk is now gone and the car drives great. I think the 'rotate the torque tube' test is the main one for clutch - although the noise was from the back it was definitely the clutch.

I've also got a timing and balance belt kit, which I'll try to fit this weekend (with Krikit tool). Then it's just the parking brake, passenger door handle, front suspension bushes, re-sealing the steering rack, changing trans fluid, etc, etc to do before it's perfect.

Mike