Lately I've been hearing a clunk coming from the rear of my 1982 Corvette, not very often, but happens lately at low speeds mostly and can be loud and quick. Runs great down the highway though. I've never driven this car hard, and it only has 57,911 original miles.

I recently had all u-joints replaced with spicers and had them double checked since hearing the noise and they're all tight as they should be. There is no howling or vibrating noise while driving 70 on the highway, just an occasional clunk at low speeds.

I had the rear-end R&R'd by a very deceiving vette shop (maybe I should post the name of the shop) back in 2004 just because I was hearing noise then, which was different from now. Turned out to be emergency brake problems, although the vette shop charged me a terrible amount of money after pulling the rear-end and replacing it with a new one. The same vette shop installed a combo stub shaft in the left side of the differential and a standard stub shaft in the right side. I never knew this until I had to get u-joints replaced. Which means the left stub shaft side takes a 1330/1350 combination u joint and the right stub shaft takes the standard 1350 u joint as it should. After getting the vette back, the noise was still there and local tire shop diagnosed the issue correctly as a emergency brake problem and ordered an emergency brake kit...fixed. The vette shop refused to work with me.


Any other ideas what the noise may be? Any help would be appreciated.

I've read on this forum that I should replace the differential fluid with two types combined, the first is GM# 1052358 (posi additive) and the second is GM# 1052271 (posi oil).

 

Yeah you should probably post the vette shop and fill out your personal info so we all know who to avoid. And try and find someone from this forum who can help so you don't need a mechanic making $120 hour off you and me.

 

Yes, what you read on the Forum is what I would do first. I've done the the grease & additive change on 2 C3s with the same symptoms and it cured both.

 

You can check one other think. Most don't know to do it. At the front of the diff where its bolted to the frame there is a rubber bumper hidden up above that sometimes wears out or falls off. Is that still there. Its hard to see. But take a look.

 

Change dif. fluid and didnt put in the additive. Mine would shudder during take off from a dead stop after driving it for a half hour. Just added the additive fridaynight and the shudder stopped.