Lexus Repair: Brakes, lexus ls400, brake master cylinder

Question
I have a 1993 Lexus Ls400.  Both front brakes are binding, both calipers become very hot after 15 minutes of casual driving.  I have replaced both front calipers and one rubber brake line.  The rear brakes seem to be doing very little as there is rust on the rotor surfaces.  

Answer
Hello Jim, There does not appear to be a question here so I will just comment. It is a possibility that you may have a problem with one of two things, your brake master cylinder or the proportioning valve. You may also want to have the play checked between the brake master and plunger rod.