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Technical Master Cylinder has me stumped

Discussion in 'The Hokey Ass Message Board' started by S2X01, Jun 20, 2014.

  1. S2X01
    Joined: May 15, 2011
    Posts: 153


    So I'm trying to get my 54 Dodge Royal rolling.
    After completely rebuilding the master and bench bleeding it, I got it installed and began to bleed my brakes. The power bleeder wasn't working so well, so a friend and I resorted to the two man method. Once we started doing that, we noticed that the piston wasn't returning as fast as it should.
    So the other day I drained everything back down so I could pull it out again. Just for fun, I pumped the brakes dry to see what would happen. Works awesome.

    Pulled it anyways and put it in the vise on the bench last night.
    Now...I'm no brake guy, But I tried a few things that made sense to try and "test" it.
    With my hand covering the fill hole, it creates quite a bit of suction and hold a vacuum. I put fluid in it on the bench, and it pumped fine. Once I put pressure/restriction on the outlet, the piston slowed down once again. After that, even without any restriction on the outlet, the piston still moved extremely slow. Drained the fluid, and it works fine again.

    Now it's completely torn apart again, and I'm stuck scratching my head.
  2. squirrel
    Joined: Sep 23, 2004
    Posts: 47,955


    master.jpg maybe there's a little tiny hole between the reservoir and the bore, that is blocked. Try cleaning it more?
  3. S2X01
    Joined: May 15, 2011
    Posts: 153


    Thanks Jim,
    I'll clean the ever-livin' crap out of it again!
    That diagram is definitely helpful!
  4. VoodooTwin
    Joined: Jul 13, 2011
    Posts: 3,455

    from Noo Yawk

    Clean the cap's vent hole too.

  5. oldsman41
    Joined: Jun 25, 2010
    Posts: 1,282


    when you have it back on the car fill it up bleed the brakes from the farthest point to nearest. right rear first than left than right front than left. after that take the cap back off and have your friend take up the play in the pedal push down easy you should see movement of the fluid by a half inch in if not the push rod is out of adjustment.
  6. tommy
    Joined: Mar 3, 2001
    Posts: 14,757

    Member Emeritus

    Did you have the pedal return spring hooked up?
  7. stimpy
    Joined: Apr 16, 2006
    Posts: 3,547


    check the ports in the metal piston behind the cup to make sure they are clean as if they are blocked the return will be slow as it form a vacuum in the front portion of cylinder those ports allow a quick release .
  8. S2X01
    Joined: May 15, 2011
    Posts: 153


    Well, I took everything back apart again. The bypass hole was plugged so I cleaned that out. Did a thorough cleaning again and everything seems to be working. It's back on the frame right now. Gonna try bleeding it out today and see what happens.....

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