Oldsmobile/Buick Repair: rear brake, independent mechanic, brake rotor

Question
My car,1996 cultless Superem, have noise like "thud thud" from rear when it run. Firstly I can feel it when I push brake at high speed. now it happen even it go down from slope without brake. Dealer asked me change capllier rotor pad for $700.I am not sure beacuse it have noise without brake. I feel like some axis unbalanced. Could you give me some suggestions?

Thx

Answer
Hello Hui,
It is remotely possible that the brake rotor could be rubbing, but I don't think that is the problem.
Even if it were the problem, that dealer is wanting to charge way way too much to replace it.
I think it is probably a wheel bearing.
Take it to a good independent mechanic, or replace it yourself.
Talk to other people in the area who have had work done by someone fair and honest, and try there.

Van