my car has absolutely no brakes in the back. I took the master cylinder off and bench tested it and found that the rear bank barely dribbled fluid out and the front was fine. Could this the the problem or does the proportioning valve have anything to do with it. Also i have heard that you have to pull up the parking brake accasionaly to keep the rear brakes in adjustsed. My car is equiped ithe disc all around. Id appreciate it if anybody could help me out with this one, thnaks yall.