Master Cylinders & Pedal Boxes

The master cylinder converts the force from your foot or the lever into pressure. Its bore diameter determines the feel: a small diameter builds pressure quickly but requires a long stroke, while a large diameter gives a firm, short pedal but requires more force. There is no universally correct size, only one that matches the number of pistons in your calipers.

For a hydraulic handbrake

Choose a 0.70" (17.8 mm) bore for typical use with stock rear calipers. A larger bore makes the lever stiff without improving lockup; a smaller one lengthens the stroke until it bottoms out before lockup.

Pedal boxes and bias

A racing pedal box houses two brake master cylinders - one for each axle - connected by a balance bar that adjusts the front/rear bias one turn at a time. On a simpler setup, a proportioning valve on the rear line does the same job: limiting the rear brakes so they do not break into a slide under heavy braking.