1976 rearend noise

[Silver1976]

Hello all, I am new here. I have a 1976 auto, and I have had a 1977 auto. Both had a rubbing noise in the rear end. It only makes noise if I am turning from a dead stop. I was told this was the posi springs and should not be worried. Does anyone else have this issue? all bearings and joints look good.

 

[78SilvAnniv]

I'm NOT an expert...

...but I think you are hearing the beginning of your rear end's side yokes wearing out.

Welcome to Corvette Action Center, Silver1976. Hopefully someone will have a better idea than my own...

My own differential would make groaning, moaning, grinding and binding noises when first rolling from a stop and also going slow around any turns from a stop or slow speed. I am sure the noise began quietly at first, but then progressed to what I remember (listed above).
I would recommend you take your vette to a vette shop, mention the symptoms you are experiencing and ask them to check the side yokes.

Due to wishful thinking and denying the inevitable, my side yokes became so bad we needed to replace the entire rear end. Maybe if your vette is experiencing the same problem mine did, you could have the side yokes replaced without having the expense of replacing the entire rear end, like I had.

When working properly, the drivetrain should not make ANY noises. Mine has been working quietly for the 9 years since the rear end change.
Heidi

 

[JohnZ]

That noise (chattering going around a corner, especially from a stop) is a classic symptom of the Posi unit's plates chattering; most of the time it can be cured by sucking out the old diff lube and replacing it with two 4-oz. bottles of GM Posi Additive and two bottles of GM Diff Lube. Then go to a big parking lot and drive some low-speed figure-8's to get the new lube/additive inbetween the plates, and the chattering should disappear in a mile or two of driving.

When the inboard ends of the side yokes become excessively worn, the stamped slingers on the yokes can rub on the outside of the diff case - easy to see; when they get to that point, they also shed the "C"-clips on the inboard end, which is not a good thing. If you see a gap between the slingers and the diff case and no marks, your yokes are probably OK.

 

[JR-80]

I remember a post awhile back about a rubbing sound during turns. It turned out to be tire rubbing on e-brake cable. Just another thing to look at.