Hy WVPharmer, welcome, so just to clarify, at the moment your truck is equipped with an underfloor boosted dual master cylinder, is that correct? When you say too much brake, do you mean the brakes would lock up on every application, or was it just the rear brakes that locked up? In order to bleed the brakes properly first the brake shoes should be adjusted as per the procedure in the manual, brake shoe adjustment can also cause problems with braking performance. You said you have the residual pressure valves in place, was the master cylinder you installed designed for a drum/drum, disc/drum, or disc/disc system?
