Volvo Repair: brake problems on a 1994 850 volvo wagon, volvo wagon, brake rotor

Question
 I have just purchased a used 1994 850 wagon with 130000 miles.  There is something seriously wrong with the brakes. After about twenty minutes of driving and stopping the brakes begin to have an aweful sound that shakes the whole car and sounds like a submerine moaning from too much water pressure. It is hard to describe. My husband replaced the rear roters.  this has not helped.  Do you know what is causing this?  

Answer
use original volvo parts when you do brakes .you have maybe bad  calipers  they heat up and freeze up most the time they go bad from using aftermarket pads they build to much heat  replace if you  can find out wich caliper is  bad  replace the caliper if you dont know you have to take it to volvo dealer .to  find out wich caliper is bad when you have the  problem stop the car go outside and feel from wich tire/brake rotor you feel most heat  the side with most heat tell's you have problem on that side .good luck