Daytona_83

First, my car is an '83 Trans Am and it has the factory posi diff. This started while I was on the Hot Rod Power Tour in Cocoa, FL. When I turn a corner at low speed, the tires start hopping and there is a clunk/chatter. I was told that I need to change out the fluid, so I bought a fluid pump, Lucas gear oil and posi additive (store brand). I pumped the old stuff out, pumped the new stuff in, and put in the posi additive. It was fine for awhile, then it started to do it again and hasn't stopped since. Sometimes it's worse than others.

Now, I have been told that I need to use GM-specific additive, and might need 2 bottles of it. I was also told that it might be good to take the diff cover off, hose it down with brake cleaner, let it dry, re-install the cover (with liquid gasket stuff) and pump all new fluid/GM additive in, then go to a parking lot and do figure 8's for awhile. Said that should fix it. Anyone else have something to say?

jmd

iTrader: (4)

Agreed on the rear cover.
Agreed on the 2 bottles (but you'll get mixed opinions on that so be prepared to do what works best for you.)
Disagree on liquid gasket. As long as the housing & cover are not distorted, a regular Fel-Pro gasket works fine.
Regular driving & turning will work the additive to the cones fine. It's probably an Auburn style which has cones.

Ultimately, the cone style 10-bolt diffs are thought of as non-rebuildable and yours may be gone but it's worth a shot with a full fluid change and use of the GM stuff.

Any pics of your car on PT?