Proportioning / Combo Valves. Disc disc Proportioning Valve. We specialize in performance brakes for late fullsize GM cars from 1955-70 and muscle cars from 1962-74,, Chevy, & Ford. Check out our tech page for information like how to test a brake booster, how to hook up a proportioning valve, how to plumb my brake lines, how to test my master cylinder and a F.A.Q's on how to calculate pedal ratio.
