The Stovebolt Site Forums The Shop Area Driveline Power brake booster and dual master cylinder

My 66 C10 had a single master cylinder with drum brakes that I wanted to update.
I purchased new drum brakes all around, a dual master cylinder and power brake booster. A new line was run to the back brakes, and everything was installed, brakes bled, etc.
Now, the fluid is going the wrong way and not reaching the brakes. Suspecting a bad master cylinder, I had it replaced and it is doing the same thing. Has anyone seen this when changing out the master cylinder?


Will Mahle

Hy mahlew, what application was the master cylinder for? Were the brakes bled with a pressure bleeder, or by the pump the pedal method? Are the brakes adjusted properly?

Will,
I having trouble with "fluid going the wrong way". If you were able to bleed the brakes, the fluid is going to the wheel cylinders and they should work. Go back and check the installation of the lines, double check the adjustment, and re-bleed the brakes. The installlation of a dual mc & booster is fairly straight foreward. You normally don't need a proportioning valve like with disc brakes so everything should be OK.
Fred

Will do. Thanks Fred

The dual master cylinder was to replace the single master cylinder. The brakes were bled by the pump the pedal method.

Hy mahlew, was the master cylinder originally for a disc/disc system, a drum/drum system, or a disc/drum system? A lot of the "upgrade kits" use a master from a Corvette which is a disc/disc system, and when using a disc/disc master cylinder in a drum/drum application you'll have to install residual pressure valves (15 p.s.i.) in each brake circuit because the master cylinder does not have them built in, as a drum/drum master cylinder would, hope that helps.

The master cylinder is for a drum/drum system. It is part BR2961 from American Classic Truck parts