My 86 T/A with a 9 bolt posi (3:27 gears) seems to be binding at very slow speeds during tight turns, The car has 27K actual miles on it, is completely stock, and has been babied all of it's life. I have taken it to my local mechanic, who checked all of the mounts and brackets, and said that everything is tight, and in good condition. The binding is severe enough to that it reverberates through the driveshaft, causing it to make a sound like a faint bell. The mechanic says that the posi unit is so tight that it is causing the unit to bind. He says that eventually it will wear enough to stop doing it on it's own. At speeds above 10 MPH, there is no noise or vibration. They jacked up each wheel and the car attempted to pull itself off of the jack with either wheel, so the posi unit is apparently working. The car makes two nearly even black streaks if you burn the tires. I have a bottle of the GM limited slip additive, and am planning a fluid change in the near future, however have read in other posts that the GM additive is not effective in the 9 bolts. Any advice will be appreciated. Charles

 

Well, this is what we did, right or wrong. Got a new gasket from Advance Auto, yes they can get them. Changed the lube, used the Lucus diff lube and Lucus Positraction Additive. The unit is quiet and rolls freely, even in tight slow turns. I may have disabled the limited slip some, because now if I peel the tires the right hand wheel makes a darker strip then the left one does. Oh, well, we only use it as a cruiser, so it does not matter. Charles