Volvo Repair: 1998 Volvo Brake Problems, 1998 volvo v70, caliper piston

Question
I purchased a used 1998 Volvo V70 a few months ago from a private party and it seemed like a great car at the time (it still is a fine car). But the brakes are doing something a little strange. There is a vibration of sorts felt when the brakes are applied. It seems to be worse braking on a decline, and if coming to a long stop. If I brake hard, you can't feel it as much. I took it to a well respected Volvo mechanic and he checked the brakes and rotors, and they are all fine. He also balanced the wheels and checked for a worped rim. All came back fine. He took it for a drive but didn't feel anything, but the streets around the shop are very poor and full of potholes. Could it be the ABS? The only other car I have owned (1990 740) didn't have ABS. Any help would be appreciated. Thanks.

Answer
it sounds like the problem is in the rear brakes.what I have seen is there is a different volvo pad for this model and requires the use of a special half shim.if they are volvo pads I would get the half shims for them and install them.they are a metal shim and only cover half the caliper piston.they should know what you are talking about.there are 2 shims for each rear wheel.theyhave an arrow that shows which end goes up.