clnhse

I have been chasing a noise since this car has been built, 2500 miles. The control arms are offset vette brakes which they did the bearings. I have new 3 inch half shafts with joints. A new drive shaft. LS conversion and 5 speed. I also have a vette brakes dual mount rear spring and c5 brakes. I also have a dontov built rear diff. 3.55 posi. Once the car gets hot I hear a knocking while turn or stop and take off. If the car cools it is fine. I have flushed the diff once and added royal purple and one bottle of additive. The best advice is to flush it again with two bottles and non synthetic?

blue by you

I use gm diff fluid and 2 bottles of gm posi fluid had the same noise now it gone

MelWff

did you correctly install the front rubber bushings that connect the rear end bracket to the frame?

GTR1999

[QUOTE=clnhse;1595980185 Once the car gets hot I hear a knocking while turn or stop and take off. If the car cools it is fine. I have flushed the diff once and added royal purple and one bottle of additive. The best advice is to flush it again with two bottles and non synthetic?[/QUOTE]

That sounds like posi chatter, which on a rebuilt diff can be from improper setup on the posi or lubrication. I would first follow what you were advised and go with 2 bottles of the GM additive and non syntetic gear oil. Do the figure 8's in a parking lot and see if that solves your issue, if not then the posi needs to be checked or you live with it.