Archive for September 7th, 2009

Hi all,

Although everything was OK with the Corvette differential when I bought the car October 2008, I had it parked in the garage over the winter and when I began driving it last Spring, I noticed a very strange behaviour with the rear end. When cold, everything was fine, but when I began driving it and had driven for about 20 miles, it began making horrible noises when taking corners and giving gas at the same time. It also wanted to drag the inside wheel and the car was just vibrating terribly. I almost had the rear end rebuilt but I didn’t have time to mess with it and then I just thought I’ll do it over the winter. Browsing the Corvette Forums about a week ago about the similar issues people have had, I accidentally found a tip which suggested to try fully synthetic 75W-140 rear end oil instead of the usual 80W-90. They also said that it’s very important to add limited slip diff additive (one 4 oz. bottle) even if the oil is certified for LSD use. So I decided to give it a try and bought also a small bottle of Ford LSD additive which was told to be the same thing as GM additive, simply different branding.

Guess what – my rear end issues are GONE. It’s silk smooth, the lock seems to be working fine and I can drive hundreds of miles without any of the issues appearing which I had before. It’s just a pleasure to drive this car now. Again it’s a good proof that American cars are EASY to fix. I’ve fixed most of the issues on my cars in a similar manner. I don’t know if the oil solved the issue permanently, but at least this summer-autumn period will hopefully be OK to drive.

The additive I used:

Oil used (two bottles):