Tips For Choosing the Right Master Cylinder for an Application

Aug 6, 2012

In this web exclusive, Bud Riser of Tuff Stuff Performance Accessories in Cleveland provides a detailed guide to sizing the master cylinder and other critical components of a custom braking system.

Vintage-style four-wheel-drum brakes “generally require a 1-inch-bore, deep-hole master cylinder such as our Model 2019,” he said, while “front disk/rear drum brakes require more pressure and usually take a 1-inch-bore, shallow-hole master cylinder and booster combo.”

Four-wheel discs require more fluid volume, so Riser recommends a 1-1/8-inch bore cylinder.

According to online literature from Classic Performance Products, the “hole” Riser mentions-also called the “pocket”-refers to the recess at the back of the master cylinder that receives the pushrod from the servo or pedal linkage.

All manual (i.e. unassisted) brake systems should use a deep-hole master cylinder designed to accepted a pushrod that already protrudes 1-1 ½ inches into the master cylinder even before the pedal is depressed.

Vacuum-assisted systems can use a deep-hole cylinder, but a shallow-hole unit is preferable, designed to accept a pushrod whose tip rests flush with the face of the booster, or as much as 3/16 inches below it.

According to Riser, vehicles with oversized wheels may require the additional volume of a 1-1/8-inch master cylinder or the additional pressure of a 1-inch, depending on the size of the rotors and calipers.

Mounting a universal booster to a vehicle that left the factory with manual brakes requires a booster bracket.

“Check the angle of the firewall surface where the brake linkage comes through,” Riser advised. “If it’s angled inward, toward the brake pedal, you will need our No. 4650 bracket. If the firewall surface is vertical, then you’ll need our 90-degree 4652 bracket. Early (pre-1973) Chevrolet pickups require our 4652A or B bracket; with one of those you can mount most boosters. Chevy trucks from ’73-’93 use our 2232 booster/bracket combo.”

For more tips on choosing brake system components, check out the August issue of Hotrod & Restoration.