I just got done replacing my rear parking break cables, rear calipers, rear wheel bearings, and rear seals. The rear disks were machined flat. I re-filled the differential with 80w90 and added the GM posi additive.

After firing it up and driving it some, I noticed a weird chatter/rattle sound coming from the right rear of the car. It wasn't loud, but it did happen fairly frequently for quick bursts. The chatter only happened when going over slight bumps and when romping on it. The sound happened very selectively. It didn’t happen very often, if at all, at lower speeds (less than 15 mph). It happened more often going up hills and wouldn't happen much, if at all, while going down hills. It happened when going over soft, round bumps on the road and didn’t happen on the jarring ones.

I pulled both axles again and took them to a machine shop to check the pervious shop's job of pressing on the new bearings/seals. They could find no faults with the work.

I'm completely out of ideas right now. The fact that it does it under such specific conditions is also weird. Is the bearing failing? It went on packed with grease and spun perfectly fine when it was out of the car.

88 GTA, 9 bolt rear, four wheel disk

 

From what I can hear from here, sounds like brake pads rattling in the calipers.

Bearings won't do that.