70GS brake issue

Discussion in 'The whoa and the sway.' started by josehf34, Jan 18, 2019.

  1. Bens99gtp

    Bens99gtp Well-Known Member

    I'm sure you have checked the pedal free play... you should just barely be able to move the pedal by the master starts to move.

    i would get a brake pressure gauge, it goes right where one of the blenders goes and see what psi your making. if under 600 psi, with all the bleeding and proper drum adjustments something in the master just isnt right.

    it is possable to have an internal leak inside the master
     
  2. Dr. Roger

    Dr. Roger Stock enthusiast

    I went through 4 new master cylinders (Autozone and AC Delco) before I got one that both worked and didn't leak. Getting the air out of the rear lines can also be a real chore sometimes. I used to pump tons of fluid through and not get all the air out. However, if I pump the brakes 3 times then hold them down before opening a valve, that often helps get the stubborn bubbles out that tend to get stuck in that long rear line. If it is only trickling out when you open the valve, it is either air still in the line or something like a collapsed rubber hose interior or bad master. You might try this first since it is the easiest. Best of luck.
     
  3. 65Larkin

    65Larkin Well-Known Member

    I'm a bit late to this thread sorry.
    If this problem started after changing the master cylinder I would be measuring the bore size of the old and the new cylinders as a change in diameter influences pedal feel and travel
     

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