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rear Brakes not releasing

Discussion in '40- & 55-Series Tech' started by Mrpoopypants, Mar 23, 2004.

  1. Mrpoopypants

    Mrpoopypants Guest

    After I use the brakes a few times, the rears stick on me. It’s not the brakes cyls because they both do it simultaneously. Cant be the booster because it only affects the rears and that would lock both front and rear. So my hypothesis is The Brake master cyl. From what I gather they are two separate systems from that point on. Any one have advice on what it could be and or how to fix this?
     
  2. Mace

    Mace rock scientist.. Staff Member s-Moderator

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    New Master?
    I bet the Booster is not properly adjusted..

    If you take the master off you will find an adjustable rod in the booster. If it is adjusted out too much it will act like you are riding the brakes at all times. But rear only..

    :D
     
  3. woody

    woody unhelpful spotter Staff Member Admin

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    rear discs or drums? If you just converted to discs and didn't remove the resid valve, you'll have problems...see the tech section.

    Otherwise, Mace is spot on with an adjustment...
     
  4. Mrpoopypants

    Mrpoopypants Guest

    Master is not new. And Still have rear drum. But the prob is not constant. It only starts after ive applied pressure to the brakes several times i.e. drivng around town, stop and go for about 20 to 30 mins. Also my booster has a small thing bolted to it just under where the Master cyl bolts on. Its a Brake Proportioning Valve. It is connected only to the rear brakes. Does this go bad? and if so, could this be the culprit?
     
  5. woody

    woody unhelpful spotter Staff Member Admin

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    how new are your hose? It is possible that a hose can disintegrate and collapse internally, allowing the high pressure of your brake pedal to push fluid thru, but now allowing the much lighter pressure of the caliper/drum springs release it...if any hoses have cracks, replace them all.
     
  6. swank60

    swank60

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    sometimes the ebrake cables will cause extreme dragging like that. It's been suggested to spray WD40 into the boot where the brake cable enters the drum. check the cable it's self, too. Mine was locking up and the cause was the cable it's self - the boot had broken open where it splits and heads to each wheel - it had gotten dirty and was sticking.

    Also, check your springs. if they aren't stout enough, they won't pull the shoes back. I'm guessing that the reason it's locking up over time is because there's already a little drag, and as it get's hotter, it expands and gets worse (just from rubbing on the drum)

    I may be wrong, but I think that if your mas cyl is going, it's more likely to loose pressure, not lock up. if your problem is hydrolic in nature, you may also check the junction that the mas cyl goes into. that controls braking pressure - should split it 60/40 front to back. I've heard that when those get mucked up, you'll have some locking too. I think it acts sort of like a check valve, and that's where the sticking happens.

    Also, back off on the star wheel a little. you'll need to do that to get the drums off to check it all out - I'd bet on mechanical issues over hydrolic any day...
     
  7. Mace

    Mace rock scientist.. Staff Member s-Moderator

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    One good question is what rig is this on.

    60's have a much different braking system than 40's (most al least) do..

    When a brake system "sticks" after a while the pressure will "bleed" off. One of the reasons some don't like line locks..

    If it is a 60ish axle (pbrake on the axle) they are self adjusting and that may indeed be the problem..
     
  8. Mrpoopypants

    Mrpoopypants Guest

    This is on a FJ40. Get this. I started out, on my way to a brake shop. Half way there i noticed the brakes starting to stick. By the time i pulled over they were completely locked, the rears that is.
    So i walked to the nearest GoodYear store, barrowed a 10mm wrench and a rag. walked back to my rig climbed under and releast the line where it meets the T and goes back to the rear brakes. Lots of flued flowed out. I closed the line and drove off. the peddle was much softer and feels much better.
    I drove around trying to get the brakes to lock up again and they did not. Going to test it again tomorrow.
     
  9. Tboss

    Tboss

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    Make sure you do not have a pinched or dented line by the drum, it would be odd to have this on both sides but stranger things have happened.
     
  10. Romer

    Romer fatherofdaughterofromer Moderator

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    So you drained the fluid and the problem went away? Is ther any fluid left in the master?
     
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