Do-It-Yourself High Performance Car Mods

Proportioning Valves

The proportioning valve controls the ratio of pressure at the front brakes to pressure at the rear brakes. Cars generally come with a fixed proportioning valve that works very well with the original brake setup. The factory setup will probably behave quite well if you have made minor tweaks at one end or put a matching set of aftermarket pads on all four corners, too. Sometimes you can adjust bias by giving the rear brakes shoes or pads with a different material, or even swapping the wheel cylinders on drum brakes. However, major changes such as a monster disc kit or replacing drum brakes with discs can upset the original balance to the point that little changes to brake pads or wheel cylinders will not bring the car back ...