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Technical 1961 F-100 front brakes headscratcher?

Discussion in 'The Hokey Ass Message Board' started by Old-Soul, May 21, 2019.

  1. Old-Soul
    Joined: Jun 16, 2007
    Posts: 3,455

    Old-Soul
    Member

    Looking for assistance from the collective HAMB brain trust on an issue my cousin is having with his 1961 F-100 unibody.
    He has a re-occurring issue with his front brakes hanging up. It varies in pressure but most recently they were locked up enough he had to release the pressure from his wheel cylinder. Once he drove home it was already binding up again.
    I was leaning towards the rubber lines, as everything was replaced with new including the hard lines and master/wheel cylinders...however after replacing both rubber hoses with quality new ones there's no change.
    He believes it's both sides locking up but passenger side for certain as that's the one he bled (and it gets ripping hot)
    No deviations from the stock system, so it's a single master etc.
    Any ideas? Would this era of master have any sort of check valve that's sticking? Perhaps the new cylinders are junk?

    Thanks!

    [​IMG]
     
  2. mopar362000
    Joined: Feb 14, 2008
    Posts: 84

    mopar362000
    Member

    Check for endplay on the petal if it's to tight will not let fluid come back to master cylinder
     
  3. Inside shoes and outside shoes different sizes, and both insides on one side and vice versa?
     
  4. Jokester
    Joined: Jan 29, 2005
    Posts: 288

    Jokester
    Member

    Shorten the shaft into the master cylinder so the port will open and let the fluid back into it.

    .bjb
     
    Old-Soul and anthony myrick like this.
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  5. anthony myrick
    Joined: Sep 4, 2009
    Posts: 4,206

    anthony myrick
    Member
    from al

    Check the pedal travel.
    Wonder if there is any piston depth difference between old and new master cyl.
     
  6. Doublepumper
    Joined: Jun 26, 2016
    Posts: 293

    Doublepumper
    Member

    M/C actuating rod too tight is my first thought. There needs to be about a quarter inch of pedal free play before engaging the piston. Might pull the drums off just to verify things are retracting properly and not hanging up.
    Hard lines too close to high heat? Air in the lines can expand with heat and cause problems like this also.
     
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  7. evintho
    Joined: May 28, 2007
    Posts: 1,150

    evintho
    Member

    Cheap, offshore drums severely out of round? Have the drums turned. It happened to me!
     
  8. bchctybob
    Joined: Sep 18, 2011
    Posts: 1,555

    bchctybob
    ALLIANCE MEMBER

    Lube the pedal assembly and make sure the pedal is returning all the way every time. My pedal was just slightly sticking and not returning completely making the brakes stayed applied. It doesn't take much. Of course, I only found this after tearing the brakes apart, adjusting the M/C rod, bleeding, and rebleeding, etc.
     
    Truck64 likes this.
  9. If you have adequate pedal free play, look at the front backing plates, specifically the three 'pads' behind each brake shoe that they ride on for wear. These can get grooves worn into them, and if the shoe gets into that groove it can fail to retract all the way. Welding up the grooves and then grinding them back flat is the repair...
     
    H380, F-ONE and Old-Soul like this.
  10. Old-Soul
    Joined: Jun 16, 2007
    Posts: 3,455

    Old-Soul
    Member

    I never thought about the pedal rod, I wasn't there when he replaced it so that very well could be the problem!
    I'll run it past him and see what he says.

    thanks fellas!
     
  11. F-ONE
    Joined: Mar 27, 2008
    Posts: 1,686

    F-ONE
    Member
    from Alabama

    I second.....
     
  12. onetrickpony
    Joined: Sep 21, 2010
    Posts: 344

    onetrickpony
    Member
    from Texas

    If it's not the rod, make sure nobody but anything but brake fluid in it. It can cause the rubber to swell and cause all kinds of strange symptoms, including random lockups.
     

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