67 coronet r/t brakes

[david bench]

Hello I'm having a problem with the brakes on my 67 r/t brand new power booster and master cylinder, new proportioning valve.new calipers in front and wheel cylinders in rear all new lines including rubber hoses. bench bleed master, then vacuum bleed all 4 wheels got straight fluid out of all 4 wheels front brakes work fine but no pressure from rear wheel cylinders. I checked the proportioning valve have tool in it to keep valve from moving, had helper pump and hold brakes cracked line at proportioning valve no pressure there then cracked line at master for rear brakes no pressure there so determined bad master. ordered new one AGAIN bench bled then installed same problem can't believe 2 bad masters in a row. I played with adjustment on rod out of power booster just changed pedal position. At wits end HELP!

 

[Jerry Hall]

When you bench bled the master cylinder, did you have pressure from both ports? If so don't use the vacuum bleeder, it's killing your master cylinder in my opinion. I ruined the rear line valve on my 70 Superbird with a vacuum bleeder. At the time it wasn't reproduced, but I eventually found a NOS one at a price. Follow the service manual for bleeding the brakes.