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Limited slip

My 87 monte carlo ss is making a grinding noise with a rythmic “clack” when i drive. It has a 7.5" 10 bolt w/ limited slip 3.73 gear ratio. I pulled the cover but cant see anything chipped or worn (can only really see the ring and pinion). How do I check the limited slip? There was no large debris in the fluid.’.

In my limited experience, they groan or shudder when turning corners. I’ve not heard them make much noise driving straight down the road with grinding or clicking. Have you ruled out other suspects like brakes, bearings, U-joints? Before I tore it down further, after finding no debris, I might be inclined to refill with fresh oil (w/LSD additive) and see if it persists. The additive can break down and then the clutches start barking.

Turbo is correct…An unhappy Posi-Traction only complains when cornering…Look someplace else for the problem…U-joints first, then wheel-bearings…

The additive can break down and then the clutches start barking.

When I was 21, I learned that lesson the hard way. I fully disassembled a posi-traction differential because of the very loud noise it made when turning corners. I could have sworn there had to be damage in there somewhere. It turned out all it needed was a fluid change. I’ll never forget that lesson.

Agree Joe; my Positraction was serviced by a mechanic who did not put enough of the special additive in the fluid, and it made the same noises. The clutches were acting up.

My regular mechanic is a GM certified mechanic to modify GM trucks and Suburbans for heavy duty towing; he added the right stuff and the noise disappeared.

I used to get the clacking when turning with my Olds posi. About every 20K or so would drain the rear end and add the additive. Its supposedly whale oil to quiet the clutches chattering.