I just redid my brakes with new cross drilled zimmermans and Metal Master Brake pads. However, now I notice a wobbling sound coming from the rear as I drive over bumps on the road. Went under the car and looked around and could not see anything loose.

Then I looked at the brake pads and they are really loose in the rear calipers. Test drove the car again and when I hear the wobbling sound, I would lightly apply pressure on the brake and the sound is gone. Checked the pads and they look like the same size as the old ones that I took off.

Could the caliper opening be worn? Any suggesting on how to fix?

 

Are you 100% sure the retaining spring is keeping the pads in place? Any chance you can get pictures? Are you sure the caliper is still properly bolted to the hub?

 

I will try to get some pics latter. The pads don't seem to touch the retaining spring. They have a lot of lateral movement (front to rear on the caliper). So when I brake lightly, I hear the pads klank up and down on the back ones.

Oh, is there any difference between the front and rear pads. They looked the same, but I don't have the oiginal box.

 

Front and rear pads are the same parts unless your car was upgraded to the BigBlacks at some point in its life.

 

I had the same problem on my 911 (same calipers as the 85 951 actually). There is a set of shims that fit between the brake pad & pistons to keep the pads from vibrating/wobbling. The shims are round and basically flat with a clip on one side that inserts into the piston and a sticky side that goes against the back of the pad.

It seems to have cured my front-end shimmy.

I think I paid about $45 for the set (2 calipers). Check your local p-car parts dealer.

Chip