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Old 07-19-2005, 03:30 PM
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Since this is a factory posi, did you add the GM limited slip differential lube? if you didn`t the rear will make all kinds of pop and clunking noises, usually the noise doesn`t show up until the rear diff gets hot. If you used standard gear lube you`ve found the problem. You can get about a 4 oz bottle from any GM dealer, or you can upgrade to a synthetic lube like royal purple which doesn`t require any anti chatter additive. Most factory posi`s had a tag on them that said "use GM limited slip differential fluid only" most people don`t know what the term "limited slip" means, so they add standard fluid. I`ve seen people in the past have the rear replaced because of the chatter, not knowing all they had to do was add the fluid. I had a 79 Z28 with a posi, the car sat 9 years and the rear chattered like crazy, I added the parts store additive that said it elimated chatter, it did no good, I added the GM additive, problem solved. In my Cutlass that I have now, I installed a posi diff, added royal purple lube alone, no chatter problems.
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