The Stovebolt Site Forums The Shop Area Driveline How to Bleed New Brake System

I finished installing a front disc brake setup onto my 1950 GMC 100 panel. The parts are: front calipers: 1985 C10, rear wheel cylinders: 1966 C10, master cylinder: 1968 Mustang, 1 inch bore bought as a kit with a combination valve mounted under it.

The brakes seem to work fine, but the pedal is unacceptably mushy. I obviously have air somewhere. The pedal is 9 inches from the floor. The first push engages at around 2 inches from the floor and is very mushy. I can pump the pedal multiple times and get the pedal to engage at near 5 inches from the floor, but the mushiness remains.

I have loan of a power bleeder. I made two circles, bleeding at each wheel twice. After finishing the 1st round of bleeding I made a guess that the bench prime of the master cylinder may not have held. I checked that before starting the 2nd round of bleeding. There was no air in the MC, so that guess was not the right one. The 2nd round did not make an improvement over the 1st round.

I have run near a gallon of DOT 3 through it. I do not see any leaks.

I suspect operator error.

Does anyone have advice on what I am doing wrong?

Thanks!