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Thread: brake question

  1. #1
    Join Date
    Jan 1970
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    brake question

    I have a question about varying brake pedal travel. Sometimes it is firm and other times it travels further before it activates the brake. When this happens I release the brake and hit it a second time. The second time the brake is firm.

    As background the perentie has a PBR master cylinder, similar to XF to EA falcon, instead of lucas. I have a rear defender disc brake axle. The master cylinder, brake lines, rotors and pads are new. The master cylinder is not losing any fluid. The rear calipers have been rebuilt. The booter has been checked for pressure and is ok.

    any advice would be appreciated. A recommendation for a brake specialist in sth bayside brisbane area would also be appreciated.

    thanks

    Peter
    L322 tdv8 poverty pack - wow
    Perentie 110 wagon ARN 49-107 (probably selling) turbo, p/steer, RFSV front axle/trutrack, HF, gullwing windows, double jerrys etc.
    Perentie 110 wagon ARN 48-699 another project
    Track Trailer ARN 200-117
    REMLR # 137

  2. #2
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    How long since change of brake fluid?

    Sorry if basic question.

    Cheers
    Simon

  3. #3
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    Check the freeplay between the booter(booster) and the master cylinder as you may have to much travel before the bypass ports in the master cylinder are closed off.

    Cheers Aston

  4. #4
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    Check your wheel bearings (esp front), sounds like pad knock back.


    Martyn

  5. #5
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    Quote Originally Posted by Bushie View Post
    Check your wheel bearings (esp front), sounds like pad knock back.


    Martyn
    bingo !

    It's so common on these things it isn't funny.

  6. #6
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    pad knock back is the first place you look,

    its caused by excessive bearing freeplay and by warped rotors

    the next thing to check is the one way valve on the vaccume supply line and the condition of the pump itself...
    Dave

    "In a Landrover the other vehicle is your crumple zone."

    For spelling call Rogets, for mechanicing call me.

    Fozzy, 2.25D SIII Ex DCA Ute
    Tdi autoManual d1 (gave it to the Mupion)
    Archaeoptersix 1990 6x6 dual cab(This things staying)


    If you've benefited from one or more of my posts please remember, your taxes paid for my skill sets, I'm just trying to make sure you get your monies worth.
    If you think you're in front on the deal, pay it forwards.

  7. #7
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    Ditto bearings... It's one of the first signs.

    M

  8. #8
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    "pad Knock Back" please explain, I havent heard the term B4

  9. #9
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    disc brake pads are released by the slight movement of the rotor pushing them back into the caliper. This is called pad knock back. When its excessive you need to pump the pedal to push them back onto the disc
    Dave

    "In a Landrover the other vehicle is your crumple zone."

    For spelling call Rogets, for mechanicing call me.

    Fozzy, 2.25D SIII Ex DCA Ute
    Tdi autoManual d1 (gave it to the Mupion)
    Archaeoptersix 1990 6x6 dual cab(This things staying)


    If you've benefited from one or more of my posts please remember, your taxes paid for my skill sets, I'm just trying to make sure you get your monies worth.
    If you think you're in front on the deal, pay it forwards.

  10. #10
    Join Date
    Jan 1970
    Location
    Brisbane, Queensland
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    thanks all for the replies. Brake fluid is new. I had the front bearings checked and all ok.

    the alternator is new but has been sitting idle on the vehicle for about 4 years before I got it on the road. So I am assuming the vaccume pump is ok.

    Where is the valve btw the alt and booster?

    Peter
    L322 tdv8 poverty pack - wow
    Perentie 110 wagon ARN 49-107 (probably selling) turbo, p/steer, RFSV front axle/trutrack, HF, gullwing windows, double jerrys etc.
    Perentie 110 wagon ARN 48-699 another project
    Track Trailer ARN 200-117
    REMLR # 137

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