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Brake the Horror........

Discussion in '"Stock" Alpine' started by burgy711, Apr 21, 2007.

  1. burgy711

    burgy711 Donation Time

    Or is it "BRAKES oh the Horror!!!" :eek:

    Update on the Caliper sticking problem..... I pulled all four pistons out and all four had some pretty serious rusting issues going on..... I put in four new Stainless Steel pistons - all new rubber fittings - new brake shoes and everything sure looks good. Got it all back together and did a good bleed of everything. Dry run and things are good they relax well and the car rolls.

    Fire up the car because of course it all sparks up good since I switched out the faulty shorting @#$#@ starter........ pump the brakes and they remain so flippen hard I'm just puzzled. While the booster isn't new it is new to me and I was under the impression that it was good. I have a second buster that I don't have a lot of trust in that I will switch out tomorrow.

    When I turn off the car the vacuum seems to relax after a few minutes and it will roll again most times. If I open a bleeder on a wheel it all will relax to the point where I can roll the car. Booster???

    At first glance I just think its a bad booster but maybe there is something that I'm missing that you all can help with??? I will try the second booster I have and see if by chance that will work. Seems like I have a lot of vacuum pressure coming from the intake manifold.... how much should I have? When I pull that hose line...... the car almost dies from too much air and there is a lot of suction on that hose. Should I be pulling air through the brake booster that would be noticeable? I don't notice air being pulled through the booster but of course there is the air filter so there must be some air being pulled.

  2. Wombat

    Wombat Donation Time


    If I have read your post correctly, when the engine is running and you apply the brakes they lock on?? If so the booster is alomst certainly faulty. Try it with the vacuum hose disconnected from the booster (plug the end of the hose to stop the air getting into the manifold).

    These boosters have a hydraulic piston that works an air valve. When you put your foot on the brake, the hydraulics move the air valve to supply air to the back (the opposite end to the cylinder) of the booster piston and vacuum to the front. This gives you the boost. When the pedal is released, the hydraulic piston is supposed to return to "off" under spring loading and the air valve is moved so there is vacuum on both sides of the booster piston. Sounds like yours isn't returning to "off" properly.

    The only time air should be passing through the booster is going in when the brakes are pressed and going out when they are released.
  3. burgy711

    burgy711 Donation Time

    Thanks Robert........ now that makes a lot of sense and that is my issue. I will try the "without vacuum" tomorrow and see..... but I think you nailed the symptom. This restoration for the past year has been two steps forward, one step back but I really think I'm just a good booster away from the shack down cruse.

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