Brake Limiters & Proportioning Valves

A proportioning valve limits the pressure sent to the rear axle. Without one, a lightened rear end locks up before the front under heavy braking, causing the car to rotate.

Knob or lever-operated

The knob-operated version is adjusted once, in the pits, and locked: it is the base setting. The lever-operated version is adjusted from the driver's seat, which is useful when track grip changes during a session or the load varies.

Where to install it

On the rear line, after the master cylinder and before the distribution tee. Install it somewhere accessible: a proportioning valve you cannot reach will never be adjusted, and one that is never adjusted serves no purpose.