Our 1978 Corvette has a noise that occurs at slow roll (at start up or slow down). We initially thought it was the u-joints or wheel bearings, but those are fine. We would appreciate any suggestions that you might have. Could it be the posi-track clutches in the rear end?

 

My 73 is doing the exact same thing. I though it had something to do with the posi-traction. Hope someone has some ideas. Thanks

 

Try changing the rear end grease and make sure it has the additive in it. That is easy to do and it very well may fix it. Usually the posi makes a popping noise in turns at slow speed though. But for about $20 you can find out.

 

My 73 rear was making a noise like maybe the emergency brakes were dragging or sticking when first letting out the clutch, I too thought it might be the clutches in the differential were sticking or " U " joints on the half shafts, Well visually everything looks fine with the brakes and " U " joints so I went after the rear, while sucking out the Diff. fluid with a drill pump and using clear Tygon tubing from Home Depot I noticed that the lube had broken down, it was black then green not uniform in color and I also noticed some very small deposits of metal in the lube when I got to the bottom. The car and power train has 30K miles on it and has never been abused, I figure I'll drain the 4 spd trans while I'm at it.
I'll repost if this did the trick.

Glenn