The Stovebolt Site Forums The Shop Area Driveline Power Brake booster installation

I recently bought new brake shoes front and back and a power brake booster with dual master cylinder to replace the single cylinder I had.
After running a new brake line for the back brakes and bleeding the brakes the brakes are worse than before. It doesn't seem like the power brake booster is working at all.
Does anyone have any advice/instructions for installing the brake booster?

I haven't done this but I think that you want to judge the pedal feel etc. without the motor running and when that feels reasonable for a manual brake, start up the motor and see how it feels.

There can be a lot of issues here. First, what are you working on? New brake shoes don't always make a brake job. What condition are the cylinders in? Also the drums & brake hoses. Are the brake shoes adjusted properly? Do you have a proper source of vacuum to the booster? Are you sure you bled the brakes correctly?
Fred

The truck is a 1966 C10, the cylinders, drums, and hoses are all good. They have been bled correctly. I am not sure of a proper source of vacuum to the booster. What would be a good source for that?

If it is a V8 there usually is a plug on the rear of the carb for that purpose. Also on the intake near the distributor. The 6 cyl should have a plug on the intake below the carb.
Fred

Thanks Fred, I will check it when I get home.

Also make sure the lines are hooked up correctly at the master cylinder. They front and rear lines have specific ports.

As Fred mentioned, brakes need to be adjusted correctly to provide enough back pressure for dual cylinder to work right.

Did you "Bench bleed" the M/C. Putting on a new M/C without bleeding it will(can) take forever and a day to bleed. Since it is mounted, leave it and pull both line off the M/C and pump the pedal slow then release the pedal slow, rehook the lines and bleed the brakes as normal-starting with the rear wheel farthest from the Tee on the rear axel, then the other rear, then front right and last front left. Once done repeat the bleeding again starting with the rear.


When you say this, is the engine running, cause without the engine running you will have NO boost.

Gotta have air in the line, when you bled the brakes did you ever run either chamber out of fluid? If so the you need to redo it. On a racecar it once took 5 hours to bleed the lines and still it wasn't good enough, after that we got a power bleeder-problem solved!

I had a similar problem when i did a power disc brake set up on my 57 belair did some research came to find out the bore on my rear wheel cylinders was 1" and needed to be 7/8" you could have the same problem