Strange thumping noise

[angry planet]

I have begun noticing a strange thumping noise coming from the rear end of my '68 vette. It is most obvious when I am coasting through a turn (either in neutral, with the clutch engaged), and it slows down as the wheels slow. I have ALMOST convinced myself that it doesn't happen when the car is in gear, but it is tough to tell over the engine noise. Wildly guessing, I would say the thumps are separated about every half second when coasting about 10 mph.

A friend suggested I check the fluid in my differential, and it looks to be at the proper level.

Does anyone here have any ideas where to start my investigations?

Thanks in advance. It feels good to post here again. I lurk all the time, but don't feel like I know enough to contribute to the conversations. I'm still learning all the time.

Neil

 

[angry planet]

I feel terrible. I did a search and didn't find anything... when I posted this, there were already several similar threads that might help me. Sorry.

 

[JWC]

Don't feel bad...... Jump right in!!!!!
The only stupid question........ you know...... Ask away!!!

 

[angry planet]

According to a previous thread, it looks like the problem is the U-Joint. Now I am trying to decipher some of the terms and find some parts. It will take me awhile to even figure out if I am in over my head

 

[Mac]

The rear differential of the Corvette is independent which means there are several u-joints; at the drive shaft, at each end of the half-shafts (between the diff and wheels) as well as bearings on each side of the diff and the trailing arms. Any of these bearing failing will cause the problem you're describing. As well, the posi unit in the diff can cause noises if it's problematic.

If you put the car onto jack stands so the wheels turn freely, you might be able to locate the source of your noise. Good luck!!

-Mac

 

[ron*d]

Have you checked your tires for a lump or something stuck in the treads ??? As Mac said .. there is alot back there and you will have to get under your car and starat pullng on your drive shafts and seeing if there is any play in them as well as your wheel bearing. look very closly at your u joints for metallic dust .. they may not have much play while your sitting still but you may still be able to see the dust meaning its time to change them out.