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Customs Brake Problems-WTH can it be

Discussion in 'The Hokey Ass Message Board' started by jackalope, Aug 24, 2016.

  1. jackalope
    Joined: Mar 11, 2011
    Posts: 687


    Here's what I'm dealing with:
    I have a 28 Model A with disc/disc
    Everything worked properly until I noticed the MC yoke was suspect (shoddy linkage) so I replaced it.
    At that point, shit went downhill. Put "new" reman unit in. Drove it a few miles and the fronts slowly started to build pressure until almost locked up.
    Bled them thoroughly again thinking maybe air or debris. Same thing. Locked up after awhile.

    Go and buy another MC and hook it up. Same damn thing.
    At this point all things point to a faulty Residual Valve. So, this evening I decide to eliminate the suspect variable (RV) and run a straight line to the front brakes and guess what...Same damn thing!

    What gives. Is it possible that both "new" MCs are bad? I'm so pissed at this point I don't know what else it could be.
    I've bled this brake system at least 10 times and done everything. I can only find posts that point to a bad MC when the pressure builds up like this.
    Any other ideas? Like I said, they worked until I pulled the original off so I know everything else should be fine. Both fronts lock up when this starts to happen.
  2. Possible brake hose internal degradation to the point they let pressurized fluid in but not back out when the pedal is released. Or brake pedal linkage is misadjusted and not allowing the rubber cups to fully uncover the ports that go from the master cylinder into the reservoir when the pedal is released.
    Last edited: Aug 24, 2016
  3. sounds like you need to adjust the linkage so you have a little "play" in the pedal.
    rfraze and Tman like this.
  4. Yup, rod is too long (that's NOT what SHE said...). Crank it shorter, keep track of how much in case you have to go the other way with it.

  5. Happydaze
    Joined: Aug 21, 2009
    Posts: 1,216


    *2 on the free play and I'll raise you a pedal return spring to hold the pedal off the master.
    Mr48chev and ClayMart like this.
  6. 2935ford
    Joined: Jan 6, 2006
    Posts: 3,684


    Yup, I suspect rod adjustment......I just finished going thru this on my '32 pickup.
    Drove out to a parts store and on the way there the truck got to the point where I didn't need to brake......wouldn't coast. Arrived at the parts store and felt the drums......ouch....blazing hot and the brake pedal was no play and solid. As well, my brake lights were stuck on.. Crawled underneath loosen the nut a few turns on the is well!
  7. Russco
    Joined: Nov 27, 2005
    Posts: 4,196

    from Central IL

    Been there too make the rod a little shorter
  8. olscrounger
    Joined: Feb 23, 2008
    Posts: 4,409


    Been there as well-adjust the rod and a good return spring. My neighbor took his nomad to a place and had them replace the mc. On the way home it slowed down til it would not roll and the front discs were HOT. Called a rollback and brought it home-adjusted the rod--all good.
  9. jackalope
    Joined: Mar 11, 2011
    Posts: 687


    Thanks fellas! I had adjusted that last night and tried it but maybe not enough. I am hopeful that a little "play" will take care of her once and for all!
    Thanks again!
  10. alchemy
    Joined: Sep 27, 2002
    Posts: 17,467


    1/8" play before the plunger touches inside the cylinder.
  11. Mr48chev
    Joined: Dec 28, 2007
    Posts: 30,198


    = between 3/4 and 1 inch of free travel at the pedal in most cases.
    Make sure that the arm for the pedal isn't hanging up on something too. Sometimes when we start moving stuff around to change something the linkage gets a tad out of alignment.
  12. jackalope
    Joined: Mar 11, 2011
    Posts: 687


    Well wouldn't ya know, that WAS the damn problem. I thought I had the length right but decided to go back and give it some "slack", put a return spring on it to prevent heavy pedal drag and rolls freely withOUT the front brakes locking up!
    Thank you all very much fellas. NEW lesson learned. Boy I wish I had posted this two weeks ago........
  13. I learned this the hard way, on a customer's car in about 1976. I still recall it, a '66 Chevy Impala 2 door HT, light blue. I didn't know about adjusting the rod with a new master.
  14. jackalope
    Joined: Mar 11, 2011
    Posts: 687


    You got that right! This is one of those things that drove me nuts. I've changed brakes and everything associated with them but this one flat out got me way outta whack! I could not figure out what the hell the problem was. I really appreciate everyone's help but also appreciate the lesson I learned ;-)
  15. jetnow1
    Joined: Jan 30, 2008
    Posts: 1,911

    from CT
    1. A-D Truckers

    Nice to see the problems solved and that Jackalope took the time to post the
    solution and to show appreciation. I wish more would post when they have
    solved their issues and what worked.
  16. Sometimes when brakes are locked up like that, you can crack a bleeder and the car will at least roll and possibly be driven a short distance.

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