Mushy brakes

Discussion in '40- & 55-Series Tech' started by Godwin, Jul 2, 2005.

  1. Godwin

    Godwin Resident Herpetologist SILVER Star

    Messages:
    4,421
    Likes Received:
    4,396
    Joined:
    Dec 4, 2004
    Location:
    Alabama
    Last week I'm out doing some field work and Wednesday afternoon a rear brake line on my 40 springs a leak, one of the rear hard lines had broken. I had a replacement line but it was 200 miles away. As a field fix I crimped the leaking line and filled the reservoir with water and bled the remaining operational rear brake. This restored most of the braking on the Cruiser. I was pulling a boat so having brakes was kind of important. On the following Saturday I replace the broken line and bled the brakes. The only name brand brake fluid on the shelf was Prestone, but in synthetic, and that's what I went with.

    So after replacing the hard line and flushing the entire brake system the pedal is soft. I figured I had air in a line somewhere. Today I rebled the system, this time with assitance, and prior to bleeding I adjusted the rears. I had my son pump the pedal several times and hold it while I opened and closed the bleeder. We did this at each corner. While bleeding I noticed no air coming out of any of the lines. The rears had good pressure and each time a strong stream of fluid was expelled. Same for the the fronts but the flow was not as heavy. Almost an entire quart of fluid has been pushed through the system with the two bleeding events, and after all this the brakes are still soft.

    Any thoughts? I wouldn't think the synthetic fluid would be causing soft brakes, but could it? A cylinder freezing up with rust in only 2 days? Still some air in the lines somewhere?
     
  2. Pin_Head

    Pin_Head

    Messages:
    14,594
    Likes Received:
    2,229
    Joined:
    Feb 6, 2002
    Location:
    OC, CA
    "Soft" is a little ambiguous. If the pedal is spongy, there is an air bubble in there somewhere. If the pedal rises when you pump the brakes, drum brakes need to be adjusted tighter. If the pedal isfirm, doesn't pump up, but the brakes are weak and ineffective, maybe the pads or shoes are bad or contaminated or one circuit isn't developing pressure.

    The most effective bleeding drill is with two persons; one to push the pedal, the other opens and closes the adjuster.
    Open adjuster, yell "down"; pedal down and hold.
    Close adjuster, yell "up"; pedal up.
     
  3. e-man

    e-man

    Messages:
    143
    Likes Received:
    2
    Joined:
    Mar 28, 2005
    Location:
    Fort Worth
    I'd get one of those vacuum things from Oreilly or Autozone. I could not get my brakes bled the traditional way. I tried for a long time before I listened to my wife and went and got the vacuum thing. Took about 3 minutes and the brakes were fully bled and worked great.
     
  4. dgangle

    dgangle total rice

    Messages:
    4,002
    Likes Received:
    17
    Joined:
    Nov 24, 2004
    Location:
    Heart of Dixie
    why in God's name would you put water in the mastercylinder? Did I hear you right?
     
  5. Godwin

    Godwin Resident Herpetologist SILVER Star

    Messages:
    4,421
    Likes Received:
    4,396
    Joined:
    Dec 4, 2004
    Location:
    Alabama
    You heard right - water. Reason being I was out in the middle of nowhere and had no brake fluid. Water compresses very little so in that regard it could be used as a substitute. I knew that having water in the lines long-term would cause problems, but at the time I decided that having functioning brakes was more important.
     
  6. Godwin

    Godwin Resident Herpetologist SILVER Star

    Messages:
    4,421
    Likes Received:
    4,396
    Joined:
    Dec 4, 2004
    Location:
    Alabama
    This description fits. Guess I'll be re-re-rebleeding soon.
     
  7. pbgbottle

    pbgbottle Forum Lifer

    Messages:
    4,725
    Media:
    92
    Albums:
    5
    Likes Received:
    386
    Joined:
    Feb 8, 2004
    Location:
    Cloverdale B.C. Canada
    water works great . i snapped a rear hard line also once upon a time . only thing i did was pinched of the rear flex line with vice-grips .filled with water .bled the air .pinched it off , had a rock hard pedal . because no fluid could flow in the rear system .i drove this way (front brakes only daily driver ) for 3 weeks before i had a day off to fix it . replaced line pulled vice-grip .poured fluid in bled air and has worked ever since . maybe your broken line was shot .and causing the pedal to feel hard . limitted fluid flow . anyways once fixed vice-grips removed pedal felt soft also . for me it was just that i was used to the water in the system . took it to my buddy's brake and muffler shop and he said everything was fine no air in system get used to it . and he couldn't believe i put water in the system either ,OH WELL . that's my .02 cents
     
  8. dgangle

    dgangle total rice

    Messages:
    4,002
    Likes Received:
    17
    Joined:
    Nov 24, 2004
    Location:
    Heart of Dixie
    You learn something everyday. I have always considered water the enemy of brakes so it seemed foreign to me. I'll keep that one in the back of my mind.
     
  9. Dragon158

    Dragon158

    Messages:
    47
    Likes Received:
    0
    Joined:
    Jun 25, 2005
    Location:
    Philadelphia
    Not sure, but is it possible that it's because you mixed fluids? I mean synthetic and DOT3 fluid, can you mix them like you did? I thought mixing the wrong brake fluid might ruin all the orings & seals, or at least mess with the tempature rating. I think it might gell up, anyone know?
    I gravity bleed everything and rarely have a problem. Maybe try that, open all the bleeders & make sure you keep the reservoir filled. If I have an air problem I'll go around and tap on the wheel cylinders, to knock loose any air that might be clinging to the cylinder walls. You waste fluid sometimes doing that though...
     
  10. Godwin

    Godwin Resident Herpetologist SILVER Star

    Messages:
    4,421
    Likes Received:
    4,396
    Joined:
    Dec 4, 2004
    Location:
    Alabama
    I had regular Prestone DOT 3 fluid in the system and replaced it with synthetic Prestone DOT 3. I would hope the manufacturer would have tested the compatibility of the fluids, but all that was available was the synthetic so that's what I went with. I've pushed at least 1 1/2 quarts of synthetic through the lines now so there should be little if any regular fluid left. But as a test I mixed equal portions of regular and synthetic fluid to see if any gelling will take place. None after an hour.

    I rebled the rear lines and readjusted the brakes and now the pedal is firm.
     
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.