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Brake trouble, push rod length to blame?

Discussion in 'The Hokey Ass Message Board' started by Beat2Hell, Jul 2, 2012.

  1. Beat2Hell
    Joined: Mar 20, 2012
    Posts: 65

    Beat2Hell
    Member
    from So. Cal

    Hey guys, so here's my situation. On my '63 Dodge D100 I have replaced the following... Master cyl. with a dual chamber unit with correct bore, front hard lines, front hoses, front drums and shoes. I didn't do the rear drums or shoes because it's really hard to find tapered axle drums. The rear drums are done for... but the shoes looked ok. I bled and bled the brakes, yes I bench bled the master as well. I just can't seem to get a good pedal, I know the rear hose could be suspect and I'm gonna swap it tomorrow. I'm starting to think maybe a bad master cylinder? Also, my friend who works in a shop says my pushrod is 3/8 of an inch too short. It's the one I pulled from the old single pot master. Would that really cause all this trouble? It doesn't seem too short to me, but what do I know? That's why I'm asking you guys. This isn't the first time I've done this kind of thing... I rueplaced everything on my girlfriends OT truck (73) and it was all bled and good to go the same day. I also helped convert a '65 Plymouth to dual circuit and it took time to find out it had a bad master cyl (remanufactured). Mine is also reman. but I don't want to just assume that's the culprit. Sorry for the long post just want to lay it all out there. Thanks in advance fellas.
     
  2. 3/8" of play is too much. what size bore is the master cylinder? if when you are bleeding it do you get a good stream of fluid when you open the bleeder?
     
  3. Clamp off the front and rear hoses - you can buy brake line clamps or use a vise grip with a piece of poster board or a rag in the jaw so you dont damage the hose . With all lines clamped off the pedal should be rock hard . If it is not then the problem is at the master . If the pedal is hard , have a buddy let the clamps go ( one at a time ) while you hold your foot on the pedal - when you feel a significant drop that will tell you where your problem lies - bad adjustment at the drum , weeping or failed wheel cylinder .... you will at least know which corner/end the problem is at .




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  4. wingman9
    Joined: Dec 30, 2009
    Posts: 804

    wingman9
    Member
    from left coast

    4t6ford, that's a good one. I've never heard that before but it makes sense. I'm glad I got out of bed this morning; I learned something. Now I can go back...
     

  5. unkledaddy
    Joined: Jul 21, 2006
    Posts: 2,865

    unkledaddy
    Member

  6. Beat2Hell
    Joined: Mar 20, 2012
    Posts: 65

    Beat2Hell
    Member
    from So. Cal

    Thanks guys, when I bleed them I get a good shot of clear fluid on all four wheels. One of the wheel cylinders I replaced was leaking so I'm replacing it right now. As far as the pushrod length... what can I do to fix this? It does get a decent pedal if you pump 'em up and hold it, but if you take your foot off it's back to no pedal. Oh yeah, it's a 1" bore in the MC.
     
  7. medicinal_marinara
    Joined: Nov 24, 2009
    Posts: 139

    medicinal_marinara
    Member
    from Oregon

    Make sure your shoes are adjusted properly before worrying about the pushrod length. If you've got too much clearance on the shoes you are going to get the pump up issue.
     
  8. jazzbum
    Joined: Apr 5, 2005
    Posts: 598

    jazzbum
    Member

  9. if the wheel cylinder bores are 1", i would agree with medicinal marinara [great name] the brakes need to be adjusted.
     
  10. fordor41
    Joined: Jul 2, 2008
    Posts: 952

    fordor41
    Member

    Still air in the system
     
  11. if the pedal bottoms out on the floor before the master piston does ,you will have air left in the master.
     

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