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1960 Cj5 Brake Issue

Discussion in 'Early CJ5 and CJ6 Tech' started by Chris Sedorchuk, Dec 5, 2023.

  1. Dec 5, 2023
    Chris Sedorchuk

    Chris Sedorchuk New Member

    Nanticoke PA
    Joined:
    Dec 5, 2023
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    6
    hello,
    replaced the master cylinder on our 1960 CJ5.
    now after driving for a 20 minutes or so, the brake peddle gets hard, and the brake lights stays on.
    the jeep also wont role on its own and becomes hard to move because the brakes are staying on.
    one we let the jeep sit for an hour its back to normal.

    note that the cap breather hole is clear and not clogged.

    any ideas.

    look like we will need to take the system apart and look for an obstruction?
     
    Chris Sedorchuk, Dec 5, 2023
    #1
    Glenn likes this.
  2. Dec 5, 2023
    Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    Tantallon, Nova...
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    Sounds like the push rod from the pedal lever to the MC needs to be adjusted- what you're describing are classic symptoms of the MC piston not being allowed to go far enough back to uncover the feed holes in the bottom of the reservoir trapping the fluid in the lines. As the wheels turn the residual pressure causes the brakes to rub & heat up, heating the fluid which expands & build pressure in the lines, causing more pressure on the brakes, more heat etc. etc. Eventual there's so much pressure the brakes lock up until everything cools down again.

    You need to adjust the push rod so there's about an inch of pedal movement before the rod contacts the piston.
     
    Howard Eisenhauer, Dec 5, 2023
    #2
    Beach66Bum, Glenn, Fresbone and 5 others like this.
  3. Dec 5, 2023
    Chris Sedorchuk

    Chris Sedorchuk New Member

    Nanticoke PA
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    Dec 5, 2023
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    Thank you,
    sounds like that's the issue. I know I have it adjusted tight. I'll run it back to an inch of paly and test it.
     
    Last edited: Dec 6, 2023
    Chris Sedorchuk, Dec 5, 2023
    #3
    Glenn likes this.
  4. Dec 6, 2023
    Rick Whitson

    Rick Whitson Detroit Area 2024 Sponsor 2022 Sponsor

    I live South of...
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    What Howard said, Good Luck.
     
    Rick Whitson, Dec 6, 2023
    #4
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  5. Dec 10, 2023
    Chris Sedorchuk

    Chris Sedorchuk New Member

    Nanticoke PA
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    Dec 5, 2023
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    6
    thank you for you help.
    unforchanlty the problem persists, at this point we think the master cylinder is sticking, it was brand new from Kaiser willy's. when we prepped it for install there was a lot of rust in the revivor.
    so not sure but going tom pull it off and take a look.
     
    Chris Sedorchuk, Dec 10, 2023
    #5
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  6. Dec 10, 2023
    Keys5a

    Keys5a Sponsor

    Florida Keys
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    Air trapped in the system can also cause your symptoms. I think the proximity of the exhaust pipe arcing around the master cylinder helps heat the master and brake fluid, and air bubbles expand with the heat causing the fluid to expand enough the activate the brakes.
    I have experienced this same issue years ago.
    -Donny
     
    Keys5a, Dec 10, 2023
    #6
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  7. Dec 15, 2023
    Chris Sedorchuk

    Chris Sedorchuk New Member

    Nanticoke PA
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    yeah I'm sure, we're going to put it off and make sure it not hanging up on a bit because of some rust or dirt. then well blead the system. hopeful that will take care of the issue. once we are done will post an update.
    thank you
     
    Chris Sedorchuk, Dec 15, 2023
    #7
    Fireball likes this.
  8. Dec 23, 2023
    Shovelhead Dave

    Shovelhead Dave New Member

    St. Louis
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    Sounds like you may have a brake hose that is suffering from separation inside preventing fluid from returning when pedal is released.
    I have seen exact same thing happen 3 times on one Jeep and 2 old Ford trucks. Pressure gradually bleeds off while sitting. Good luck.
     
    Shovelhead Dave, Dec 23, 2023
    #8
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  9. Dec 23, 2023
    Oldpappy

    Oldpappy A.C. Fults - Curmudgeon at large 2022 Sponsor

    East Tennessee
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    Could be any of the things suggested, however if the problem was not present before replacing the master cylinder I would wager the push rod just needs to be adjusted a little shorter. If it does not allow any free play at the pedal it would act as if you drove around with your foot on the brake pedal, and this would create some heat.
     
    Oldpappy, Dec 23, 2023
    #9
  10. Dec 28, 2023
    Chris Sedorchuk

    Chris Sedorchuk New Member

    Nanticoke PA
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    thank you
     
    Chris Sedorchuk, Dec 28, 2023
    #10
  11. Feb 9, 2024
    Chris Sedorchuk

    Chris Sedorchuk New Member

    Nanticoke PA
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    Hello all who replied,
    it turns out the the original style master cylinder from Kaiser willys was loaded with fine rust. took it apart cleaned it and we're back in business.
    again thank you to all gave us advice.
     
    Chris Sedorchuk, Feb 9, 2024
    #11
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  12. Feb 9, 2024
    colojeepguy

    colojeepguy Colorado Springs

    At the foot of...
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    :mad:so frustrating when new parts are trash!
    Glad to hear you got it fixed.
     
    colojeepguy, Feb 9, 2024
    #12
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