Yeah, I know it dont sound good. When I am moving very slow in traffic, my right rear wheel area makes a clunking sound and I can feel a kind of bump or twist in the car. Could this be the differential or rear spindle?

My '77 does the exact same thing and I really want to know what it is too. It bothers me and has been doing it for years. I was just going to wait until it broke so I know exactly what it was, then fix it.

|QUOTE|RXWHITE74 said: Yeah, I know it dont sound good. When I am moving very slow in traffic, my right rear wheel area makes a clunking sound and I can feel a kind of bump or twist in the car. Could this be the differential or rear spindle? |/QUOTE|

Have you guys ever put whale oil in the diff? The posi-traction units in corvettes have a tendency to chatter, and clunk. It sounds like it is trying to destroy itself. You need to go to your nearest chevy dealer and get a 4 oz. bottle of "Limited slip axle lubricant additive" part # 1052358. I t costs $5 or $6 a bottle, and it fixed mine in 50 feet. It has never done it again.. Of course, it may be something else, but this is a very easy, inexpensive fix, if it works for your problem..

Check your side U joints coming from the differential to the 1/2 shafts. Make sure the play is within specs

How old are your shocks? Didn't have the bump and twist, but I had a clunking sound coming from the right rear area that went away after I replaced the shocks all the way around. Turned out the top bushing on the R.R. shock was worn away causing the darn thing to just slap around up there.


Jim O.

|UPDATED|7/25/2002 11:08:52 PM|/UPDATED|

The binding and popping from the posi clutches normally do not occur when the car is driving in a straight line. The posi additive should be in there anyhow and its cheap so you can certainly give it a try. The U-joints, shock bolts are more likely causes. Check all of the other rear suspension bolts for tightness too. That's about it for inexpensive stuff. Good luck.

Thanks a bunch guys & gals. I will try the posi-lube. I did look and try to shake the u-joints. I didnt try the shocks. For all I know, the shocks may be the originals.

Sometimes the posi additive needs as long a a week to soak into the plates. Doing figure 8's in a parking lot accelerates the process, but give it some time before you give up on it.

How difficult is it to change the fluid in the differential? Do I have to remove the rear spring?

|QUOTE|VTHokie77Vette said: How difficult is it to change the fluid in the differential? Do I have to remove the rear spring?|/QUOTE|
Dale, no you don't. You should remove the spare tire and tub. Makes getting to the plug easier. On the rear of the carrier you will see a plug, that's the one you want. Go to a hardware store and buy a hand held "transfer" pump. It is like a cylinder with two hoses coming out of it, and a "T" handle. (Costs about $10)This will make changing the rear fluid easier, that's how I did mine. Also, you need two bottles of GM gear lube and one bottle of posi additive. Put the posi additive in first and then top off with the gear lube.
Hope this helped ya!!
Chris