Cv joint clunk - continued...
 

From the beginning... Some time ago I noticed a clunk from the rear of my car (911 SC 78) which was caused by a torn cv boot and the grease was all over the place.. To be sure, I replaced both Cv joints on that axle.

This resolved the issue partially... Most of the time the noise is gone now but it still pops up from time to time and I have the feeling it is getting worse... It seems to start as soon as I have driven some time.

What could this be? I thought about an insufficient amount of grease? So when the grease gets fluid after driving a while, you can notice the clunking? Does this make sense? Fyi, I used the 80g grease which came with the joint and boot.

What I'm planning to do tomorrow to track the noise down:
Get the car on jack stands and have my girlfriend run it so I can get under it to track down where the noise comes from.. Any other suggestions / idea's?

Thanks

A new CV joint by itself will not clunk. Have you performed the necessary retorque on all of your CV bolts? This usually after ~200 miles. Assume you got the cupped washer in the right way and seated the clip into the axle grooves securely.

A clunk may be something as simple as the sway bar and sway bar mount, or a shock that was not tightened down and is clunking on small bumps. Or, a loose wheel. Think what suspension work you may have done recently as well - connection?

Just to confirm: You are saying a new CV joint, even if it is insufficiently greased, can not clunk?

And the noise is certainly linked to CV joints as it disappears if I press the clutch...

Any thoughts?

Thanks

Retorqued all bolts but none were loose + i'm using nordlocks... Shall test drive tomorrow to see the result.

Any other thoughts?

Are you saying that the noise stop when you press the clutch while the car is coasting?

Yes

Well, CV joints still turns while you coasting with the clutch disengage, so your noise is not from the CV joints.

The noise can be heard under load and under deaccelaration... Once I press the clutch the noise disappears.

What can cause this then?

Rubber centered clutch?

Just because the boots on the other side aren't bad, it doesn't mean there won't be some wear.

This isn't a pressing issue, so you can take your time to figure it out before spending more money. CVs generally clunk under pressure. I am thinking the rubber clutch isolator is more noisy on coast/ on off throttle situations.

I really think it is related to the CV joints as it only started again after 30-40 miles after replacement of the CV joints ..
Can it be related to the amount of grease I used? Scenario that crossed my mind: Once the car is warmed up and the CV grease is very fluid, the noise starts again as there is a lack of lubrication due to insufficient grease? Seems a realistic analysis?

Exactly how much or how little grease did you use?

Noise are really hard to diagnose through the forum. Does it clunk once with each wheel rotation? Does it clunk when turning and straight? Does is clunk in gear and neutral? Does it clunk when the engine is off? Does is clunk if you jack the rear of the car in the air, engine off, no load and you rotate the wheel by hand?

I used the 80g grease which was packed with the new CV joint so that should be fine...

Retorqued the bolts on the passenger side as well (which I didn't touch before as I replaced both Cv joints on the drivers side only) and there were some which were a "bit" loose...
Went for a testdrive today and all was good for 40 miles but when I returned home I could hear the clunking starting again...
I am suspecting the bolts coming loose and noticed that no Schnorr/ Nordlock washers are present on that side. ( I did use Nordlocks on the new CV joints and they were still snug) So I know what to do tomorrow...

Not sure why we are still discussing the CV joint as the noise stop as soon as you press the clutch whether its under load (under acceleration) or off load (while coasting) as you have reported in the prior posts.

I agree . . . if my car exhibited similar symptoms, I would be looking at the clutch assembly (as others have mentioned). For starters you could look into a hole in the bell housing and see if there is any visable carnage . . .

I am learning by the day so excuse me for my ignorance and for thinking out loud ...

If it is clutch related, how can you explain then that everything is perfect for 40+ miles and then slowly starts to clunk again ...
I would expect to hear it from the start and always, no?

Can't it be that the CV bolts on the transmission side loosen up (ie. after x miles) and this triggers the clunking to start again? And depending on load / decelaration / ... the noise can be heard?
Is this analysis completely wrong?

I'm not discounting the CV here, but if the noise appears after 40 miles, it may be related to heat getting built up within the clutch pack. And since it goes away when you depress the clutch I'd be thinking that. Get a remote microphone and stick it in a few places (like on top of the bell housing to hear the clutch), or near the CV joint. If you have the rubber centered clutch, I'd be thinking that is the place.

Where are you located.....maybe a local Pelican could lend an ear so to speak.
Can you capture this noise on tape and post it?
Does it matter what gear you're in?

Url - bullethole has a good point about the clutch and yes, the CV bolts could be loosening up (not likely in just a 40 mile time span, though) - like others have pointed out however, the "noise stops when clutch actuated" element is not consistent with a CV problem. At least it is easy for you to verify that the bolts are loosening or not . . .

Have you tried tightening the axle nut? I've seen those come slightly loose and make noise. If it gets loose and stays like that you can damage the wheel bearing and cause a clunk. I have a similar clunk and it is because I destroyed the wheel bearing at the track this weekend. The easiest way would be to check for play in the wheel.