When in a parking lot, turning either way, my rear end acts as if both tires are tracking at the exact same speed, causing one side to jump/chirp the tires. It acts like a detroit locker or something just for the dragstrip.
What would cause this problem. I heard that it could have the wrong lube in it, with no posi additive, causing the clutches in the rear end not to free up when they are supposed to, allowing the outside wheel to rotate faster than the inside wheel. It is an 88IROC with posi rear.
All help is appreciated....
Thanks, Brandon

 

Yup, sounds like somebody changed the fluid in it at some point, and didn't put in the additive.... put in the additive.

 

And since you may have excess bronze floating around in there now, and if you haven't changed the diff oil in the last 15,000 miles, you might as well drain it first.

And regardless of the type of refill oil you use (even synthetic) you NEED the friction modifier in Saginaw and Borg posi axles up to about the 1994 model year.

 

Thanks, I'll look into the fluid swap and additive.
I really appreciate the help...

 

When you open the diff cover, look for metal on the magnet on the pan. My car did the same thing when it was "new" (35k miles on it) Turned out that the Saginaw limited slip governor had shelled out and destroyed the differential. I had a friend that worked for GM at the time (also owned an IROC) and said that the differential was a known problem on those cars and GM considered any TPI car running one, to be living on borrowed time.
BTW, his diff shelled out at just 12k miles.