by Louisville Lanning » Fri Dec 07, 2018 11:12 am
Dave, you may want to see what I did 10 years ago with my 4-wheel disc system and power brake booster. Here's what I wrote:
A manual dual master cylinder was installed as a brake system update when the engine work and restoration was done in 1995. Braking is slow and the pedal pressure required for quick stops is excessive. For autocrossing an additional update is necessary.
The old master cylinder was replaced with a BM1746 GM 7” dual diaphragm booster with dual master cylinder. The cylinder has a 1-1/8” bore and can be used with either two or four wheel disc brakes. The booster was supplied by Master Power Brake, Mooresville, NC and was designed for 1964-72 GM mid size cars and the 1967-69 Camaro/Firebird.
Jack Brown Engineering, Louisville, KY performed the change over. The 7” booster was installed without modifications to the firewall or inner fender. The clevis pin was connected to the existing hole in the pedal without modification. A custom bracket was fabricated to shim the booster to the firewall. The shim was used mainly to provide clearance for the master cylinder with the underside of the hood. Vacuum to the booster is provided via a 3/8” diameter rubber fuel hose to avoid later problems with hose collapse. The engine had no problem providing 18 inches of vacuum without a reservoir. An adjustable proportioning valve is located on the master cylinder and a balance block was installed on the inside firewall above the throttle pedal (part number and manufacturer unknown).
The booster modification provides an impressive improvement in braking with reduced pedal pressure. The next step will be the replacement of the front stock drum brakes with disc units for ultimate stopping power.
Booster Master Power Brake, 110 Crosslake Park Road
Mooresville, NC 28117
888-533-1199
John Lanning
President - V8 Registry
President - Derby City Corvair Club
'65 Corvair / Mid Engine Cadillac Conversion