Ok, 1985 1/2 ton, converted to 10 bolt front 3/4 ton, and a 14b FF, with 10 bolt front rotors, weld on brackets, and 3/4 ton calipers. WTF? Spongy pedal, gets hard when engine isnt running, (like all do) but start the engine, the pedal goes to the floor. No tech gurus discussing the cross sections of the master cly, or the proportioning valve. I JUST WANT TO KNOW HOW TO GET IT TO WORK RIGHT. Stock prop valve bypassed and CORVETTE Disc/Disc, master cly installed. Didnt fix. Respond only if you've had this problem and fixed it, or know how to.