drivetrain noise coming from '71 2.8cs

D

dwa1971

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So I am reaching out in hopes that this is a common problem to save some time. When I drive from a start and get over 5-10 mph I start to get a clicking noise and it just gets worse (it is not the engine coming from rear or end of tranny tunnel) and when I engage the clutch it goes away regardless of speed. It almost sounds like something is hitting on every rotation like the driveshaft but as I go faster it clunks harder and harder (I can't imagine a thrust bearing doing that but maybe). It's one of those things that if you were in the car you would know ASAP. The car runs and pulls strong and it changes gears fine. Maybe it is a tranny support that is just vibrating like crazy but the putting clutch in probably throws that theory away so any help would be greatly appreciated. Feel free to ask more detailed questions if needed as I know this may be a little pie in the sky.

Regards,
D

'71 BMW E9
'88 BMW M6
'79 Porsche 930
'75 Triumph TR6
 
This could a number of things. But have you checked the rubber donut that connects from the trans to the drive shaft? It might be starting to go. I was told this was a very common issue with 2800's and if it persists the shifting components can get damaged - which are getting harder and harder to find..
 
My first guess would be a bad transmission mount. Under load it allows the driveshaft to torque to one side, but with the load taken off (clutch disengaged) it straightens out.

Dan
 
what Dan said...

Lost the rear trans mount one day. On hard turns it would thump-thump-thump against the body.

It's about the size of a spool of thread, with metal stud on each end. 17 mm nut on each stud, IIRC. Go look and see, it's between the crossmember and the rear side of the trans. Check the donut while you're there. Don't drive much further without resolving the issue, okay?
 
thank you

I will check it out. The responses are greatly appreciated and I am glad that I wasn't far off with my thoughts on the issue.
 
one more ...

revisiting this thread, I read that you said it is clicking. That is unlikely to be the sound of a bad donut or failing center bearing.

Check that the CV joints on the rear half shaft (inner and outer) are securely bolted to the drive flange of the stub axle on the outside, and the drive flange of the differential on the inside. The cap screws were likely set in with loc-tite or similar and I have found them REAL hard to remove... you're just checking that they are still torqued on as they should be. A loose one will be immediately obvious.
 
clicking vs thumping

Thanks for the follow up but what you described in your first post is more of an accurate description of the problem.

dwa1971
 
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