Visit Our Master Cylinder Store

The Right Stuff Master cylinders are available with a 1" bore or 1.125" bore in standard cast iron or in a aluminum chrome configuration.

Visit our store to see the various styles and prices.

Choosing the Right Master Cylinder

The wrong master cylinder can make a good brake system function very poorly.  This is an easy diagnosis, but the more difficult question is often what master cylinder is right for the job. Master cylinders in the classic car industry are often referred to as drum/drum, disc/drum or disc/disc.  These designations refer to a master cylinder that "in many cases" is correct for that type of system.  Unfortunately, just knowing that a car has front disc brakes and rear drum is not always enough information to pick a master cylinder.  Each brake system is unique, so the best we can do is offer advice as to what master cylinder may work. Variables such as whether or not the system is power, the size of rotors, caliper piston quantity and size can play a role in what master cylinder is correct. 

A few notes about our master cylinders:

• Master cylinders with a smaller bore diameter will require less pedal pressure to stop, but will result in a lower brake pedal.  Inversely, you will have to press harder on the brake pedal with a larger diameter bore, but you will have a higher pedal.
• The only difference between a manual master cylinder and a power master cylinder is the depth of the bore.  Manual master cylinders have a deeper hole in the piston to keep the pedal rod that pushes into it from coming out.  Power master cylinders have a shallow hole, because they are up against the booster.  Most of our master cylinders come with a deep pocket and a "bullet" that can slide in to make it shallow. This allows them to function in power or manual systems.  See photos below.
•  Our GM master cylinders mount on two studs.  The holes are 3.375" apart center to center.
• When setting up a power brake system, inspect the booster rod length and master cylinder pocket depth. The booster rod should protrude from the booster face approximately the same length as the depth of the pocket in the master cylinder. Short systems generally use a ¼" rod and pocket. Long systems use a rod and pocket of approximately 1 ½".
• In 1967, federal law mandated the use of master cylinders with two ports.  This split the brake system into front and rear and ensured that a brake system would not go out completely due to one broken line or blown hose.
• As a general rule, the majority of braking occurs in the front of a brake system.  This is not due to different output pressures from the master cylinder.  Both ports of a master cylinder provide equal pressure.  A proportioning valve determines front to rear bias of a brake system.
• Many master cylinders have a large and a small reservoir.  This is due to the fact that as disc brake pads wear over time, more fluid displacement will be required to push the caliper piston in than the rear drums will need.  Therefore, the large reservoir is for the front discs and the small is for rear drums.