Soft brakes after rear disc install

KosmicKuda said

I don't mess with power brakes at all on old Mopars.....but I think your issue may be the piston in the MC is starting too far in. You are not uncovering the rear port to feed the fluid into the rear piston area.
Is there an adjustment somewhere to shorten the pushrod?

That 1/4" metal piece may be the clue.

Click to expand...

thanks for replying, as I ment to type up a conclusion for anyone in the future who stumbled onto this thread.

The problem was 3/8" of preload on the m/c. I removed the pushrod from my booster, removed the threaded acorn bolt, cut 3/8 off the end, ran a 1/4-28 tap to clean up the threads, and reassembled. No more preload on the m/c and perfect pedal height. Brakes took a couple bleeding sessions to get all the air out but they are now working great and I have no brake safety light when fully applied.