76 mushy brakes, help?
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Suspension, Brakes and Tires Discussion, 76 mushy brakes, help? in Item Specific Cadillac Discussion; i have a 1976 hease, based on the 76 fleetwood (500ci). Recently when i brake i can allmost put my ...
  1. #1
    76CaddyHearse's Avatar
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    76 mushy brakes, help?

    i have a 1976 hease, based on the 76 fleetwood (500ci). Recently when i brake i can allmost put my foot to the floor before brakeing starts. what should i be looking at to repair, master cylinder?

    thanks,
    Nik

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    EcSTSatic's Avatar
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    Re: 76 mushy brakes, help?

    Check your fluid level. Is it topped off? Does pumping the pedal restore power? Any leaks around the wheels or other brake system parts?
    Give us more to go on.

    What's a "hease"?

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    Re: 76 mushy brakes, help?

    Ooops! It's a hearse. I got it!

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    Re: 76 mushy brakes, help?

    yea sorry hearse on a commercial-limo chassis.

    fluids are topped, and pumping the brake doesn't seem to have much affect. And no leaks.

    thanks.

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    Re: 76 mushy brakes, help?

    Before you start replacing stuff randomly, you should bleed the brakes first to see if that helps any. If not, then I would first suspect a bad proportioning valve.

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    Re: 76 mushy brakes, help?

    i'll give that a try, some one else suggested bleeding to try to make sure there is no air in the system.

    what is a proportioning valve?

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    Re: 76 mushy brakes, help?

    Do not just bleed the brakes. Replace all of the old fluid. Bleeding only removes some of the old fluid. The funny thing about brake fluid, it absorbs moisture. That turns it into a sloppy mess. Replace all of the fluid, and go from there. If is is still mushhy, it may be a bad brake line. The rubber gets old, and will expand when braking, which is not good. These are your two main areas to attack first.

    Don

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    Re: 76 mushy brakes, help?

    Quote Originally Posted by 76CaddyHearse
    what is a proportioning valve?
    A proportioning valve regulates the pressure in the rear brake lines to keep them from overpressurizing. The rear brakes require less pressure to operate.

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    Re: 76 mushy brakes, help?

    Pumping the brakes will restore the pedal if it was an air-in-the-line problem. You either have a bad master cylinder or the vacuum booster isn't working.

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    Re: 76 mushy brakes, help?

    Quote Originally Posted by EcSTSatic
    Pumping the brakes will restore the pedal if it was an air-in-the-line problem. You either have a bad master cylinder or the vacuum booster isn't working.
    He's got Hydroboost though, right?

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    Re: 76 mushy brakes, help?

    No, it's DEFINATLY NOT a power booster problem. A power booster problem would do the exact opposite of the problem he's describing. If it was a power booster problem, the pedal would be very firm but you will have very little stopping power.

    Pumping the brakes will NOT restore firmness to the petal if there is air in the line. Pumping the brakes releases the vacuum from the booster so it may get a little more firm, but not much.

    It could be (in no particular order):

    1. a master cylender problem
    2. a bad proportioning valve
    3. air in the line
    4. a leak
    5. old rubber brake lines
    6. internal leak in a caliper
    7. bad cylender in one of the rear drums <-definatly check for this one
    8. poorly adjusted rear drums

    I think thats all of them...


    EDIT: Yeah I forgot one... It could also be the metering valve.

    ANOTHER EDIT: It is good to flush out all the brake fluid once in a while like Dadillac said. This prevents the lines from rusting on the inside. Although, water is a liquid, and liquids can't be compressed. Therefore, diry brake fluid will not soften your petal. It may however reduce the life of your brake system, and could cause this problem in that respect.

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    Re: 76 mushy brakes, help?

    thanks for all the good info! i'll try replacing the fluid and look around for bad lines and anything amiss this weekend.

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    Re: 76 mushy brakes, help?

    Quote Originally Posted by 76CaddyHearse
    thanks for all the good info! i'll try replacing the fluid and look around for bad lines and anything amiss this weekend.
    That's a good thing to do regardless of a problem. Moisture in the lines drops the boiling point of the fluid. if you overheat the brakes on twisty roads for example, the fluid can boil over.

    Please let us know what you find wrong with your brakes.

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    Re: 76 mushy brakes, help?

    will do, i may have overheated my brakes, the hearse probably weighs 6000lbs and i carry about 1500lbs of equipment with it, if your currious you can see it on my webpage www.airportcircle.com click on the word "hearse"

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    Re: 76 mushy brakes, help?

    Nice looking Caddy. Still has that morbid look though.

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