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'47 Dodge brake issues

Discussion in 'The Hokey Ass Message Board' started by INJUNTOM, Dec 28, 2010.

  1. INJUNTOM
    Joined: Jun 11, 2006
    Posts: 548

    INJUNTOM
    Member

    Been fighting this for awhile, and as simple of a system as this is, it's a head scratcher.

    Basically we are getting a buildup of pressure in the brake system and after driving a few miles, it will drag the car down to where it will barely move, and you can't even push it. After it sits overnight you can push it all you want.

    Being that it uses a hydraulic brake light switch, the brakes lights will stay on when this happens.

    The crazy thing is that you can start the car up cold and let it idle for 15 - 20 minutes and watch the brake lights come on...without ever driving the car.

    We've had the master cylinder apart several times and no problem found.

    I did put in a rebuild kit when we first started trying to get this thing back on the road as well as replace all the wheel cylinders (master wasn't available new)

    I need to either fix this thing or find a cliff to drive it off of...
     

    Attached Files:

  2. brad chevy
    Joined: Nov 22, 2009
    Posts: 2,627

    brad chevy
    Member

    What kind of system are you running,stock master or added on booster type master.?
     
  3. INJUNTOM
    Joined: Jun 11, 2006
    Posts: 548

    INJUNTOM
    Member

    Everything is stock on this car - under floor master, 2 wheel cylinders on each front wheel, one on each rear wheel.

    Pedal has been backed off to where the pedal is at the halfway point when cold..
     
  4. JohnEvans
    Joined: Apr 13, 2008
    Posts: 4,883

    JohnEvans
    Member
    from Phoenix AZ

    Sounds like the M/C piston is not returning all the way. Wrong kit or piston hanging up . Go back into the M/C and make sure the front cup is returning far enough to clear the smallest hole you can see through the filler opening.
     

  5. INJUNTOM
    Joined: Jun 11, 2006
    Posts: 548

    INJUNTOM
    Member

    That's kinda what we were thinking, but what about the fact that it will do it without even driving the car?

    Will definately look into the relationship between the front cup and the return hole.
     
  6. 302GMC
    Joined: Dec 15, 2005
    Posts: 6,923

    302GMC
    Member
    from Idaho

    Adjust the pedal free play. When it's right, you'll have 1/2" or so play before the pushrod engages the piston.
     
  7. hkestes
    Joined: May 19, 2007
    Posts: 570

    hkestes
    Member

  8. INJUNTOM
    Joined: Jun 11, 2006
    Posts: 548

    INJUNTOM
    Member

    We actually backed it off much more than that - several inches of travel.
     
  9. INJUNTOM
    Joined: Jun 11, 2006
    Posts: 548

    INJUNTOM
    Member

  10. SKULL ORCHARD
    Joined: Jul 22, 2009
    Posts: 431

    SKULL ORCHARD
    Member
    from KS
    1. The Gas House Gang

    its the rubber brake hoses at wheel cylinders, can you tell witch of the wheels are dragging fluid gets thru under pressure but is not retuning to m/c usually caused by rust at compression crimp
     
  11. SKULL ORCHARD
    Joined: Jul 22, 2009
    Posts: 431

    SKULL ORCHARD
    Member
    from KS
    1. The Gas House Gang

    been there it a bitch.
     
  12. plym_46
    Joined: Sep 8, 2005
    Posts: 4,018

    plym_46
    Member
    from central NY

    In the bottom of the MC reservoir, you should see two holes, one to provide fluid to the piston, and one to relieve pressure when the pedal is released. If both hols are not opened the pressure will build up holding pressure to the wheels. Look into the res with a decent light, should be a hole about the size of a pencil lead and a smaller one adjacent to it a bit smaller. Use a piece of mechanics wire to assure they are unplugged. Any bi of rust or debris will cause the problem you describe. Secondarily, assure the MC cap has a vent at its free, also leave some space for air at the top of the reservoir.

    then check the hoses to the wheels.

    you only need about 3/4 inch of free play at the pedal.
     
  13. INJUNTOM
    Joined: Jun 11, 2006
    Posts: 548

    INJUNTOM
    Member

    That's a good thought. I've heard of the rubber coming apart inside and causing this as well.

    BUT - when it happens it effects all 4 brakes (can tell because we have it in the air and can't turn any of the wheels)

    If we crack a bleeder they all 4 release.
     
  14. My guess is there a part of the exhaust that is very close, or contacting one of the brake hard lines.

    As the car warms up it is heating the brake fluid (or water) in the line and causing it to expand and apply the brake.
     
  15. INJUNTOM
    Joined: Jun 11, 2006
    Posts: 548

    INJUNTOM
    Member

    I've been having one of my guys work on the car when there are no customer cars, and I believe he's checked this but he may not have seen the 2nd hole. I'll ask him tomorrow.

    Will check for adequate venting.

    And I hear you on the leaving space thing...I ran into that years ago on my '57 Ford PU
     
  16. INJUNTOM
    Joined: Jun 11, 2006
    Posts: 548

    INJUNTOM
    Member

    I'll double check that, but I'm pretty sure the exhaust is nowhere near the brake lines.
     
  17. Big Bad Dad
    Joined: Mar 27, 2009
    Posts: 317

    Big Bad Dad
    Member

    I had this happen on a Dodge years ago. It was the rubber brake hoses. They were old, but still looked good on the outside. They were swelled and deteriorated on the inside. The fluid would force through them under pressure when the brakes were applied, but did not all return when the brakes were released.
     
  18. SKULL ORCHARD
    Joined: Jul 22, 2009
    Posts: 431

    SKULL ORCHARD
    Member
    from KS
    1. The Gas House Gang

    have You had any luck ? let us know.
     
  19. INJUNTOM
    Joined: Jun 11, 2006
    Posts: 548

    INJUNTOM
    Member

    Got the same reply at the Dodge forum with pics and I think it's fixed. Just went out there, and looked into the master (spotless BTW, due to lots of fluid being flushed through it), and could only see the one large port. Was starting to think maybe the wrong master, so I go get my trusty Snap On straight pick, and probe around in there, and find no signs of a port, but I keep scratching anyways in the area that I think it should be in, and then start snagging on what appears to be a casting porosity, then go ahead and start forcing the pick into it until some fluid starts coming up out of it. A little more forcing, and some black cloudy looking stuff starts coming out with the fluid.

    I really wasn't looking for something like this because it would seem that the pressure would stay on the system without even driving it.

    Now I get to take my wife and mother in law for a nice long ride for the first time in 25 years. My wife and I have driven it for a couple short rides, but not really enough to be satisfied.

    Now to find some park brake parts for this thing...
     
  20. INJUNTOM
    Joined: Jun 11, 2006
    Posts: 548

    INJUNTOM
    Member

    Yep, see my post above. Now all I have to do is take it for a ride tomorrow for about 5 miles or so and see what happens..

    Thanks for all the help guys :)
     
  21. SKULL ORCHARD
    Joined: Jul 22, 2009
    Posts: 431

    SKULL ORCHARD
    Member
    from KS
    1. The Gas House Gang

    nice good to hear it works
     

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