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Thread: Braided lines causing squishy brakes?

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    Racer Decade Plus User Adam B's Avatar

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    Braided lines causing squishy brakes?

    right, i have a mk4 fiesta, has the standard non-abs servo and m/c. (4 outputs - 2 to front, 2 to rear through an AP racing twin pass bias valve)

    i run focus rear discs and brembo 4 pot front calipers. this setup before my engine conversion worked perfectly every time with no squishyness, or sinking pedal. (when on original m/c. hard lines + braided flexis, standard bias valve thingies)

    i've had a problem with them ever since my engine conversion.

    at that time i fitted:
    new servo
    new m/c
    fully braided lines from m/c to caliper
    AP twin pass bias valve
    and the vacuum is now off cyl 1 (throttle bodies) instead of off the plenum of the original engine.

    i'm still running Dot4 brake fluid (but im unsure of the quality)


    my symptoms are:

    sometimes when i hit the brake the pedal goes almost to the floor, hit it again and it has regained pressure.

    if you pump the brake up then keep applying pressure the pedal slowly goes to the floor


    the system has been bled through numerous times, various orders and different ways... taking calipers off, turning upside-down etc but always with the same brake fluid. (cant remember when i bought it, although it was quite a few years ago).

    before i go mental, and start replacing stuff, anyone got any ideas?

    My Project... Fiesta D-TEC

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    Spanner Monkey longlegs's Avatar

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    Re: Braided lines causing squishy brakes?

    exactly the same problem i had with my old corsa combi van changed fluid a couple of times tried bleeding it over and over .put a brand new master cylinder on still the same i put it down to servo never did find out as i got rid of it as didnt need it any more.

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    Re: Braided lines causing squishy brakes?

    If there is no fluid leaking then I would say the seals on the mc are knackered.

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    Racer Decade Plus User andypipe's Avatar
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    Braided lines causing squishy brakes?

    Have you run the pipes in a different position. Suffered with spongy pedal for 20 years and found the problem was the pipework was higher than the master cylinders


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    Bodger

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    Re: Braided lines causing squishy brakes?

    Also if you have multiple take-offs from them master cylinder i.e. for dual circuit brakes, are you sure you have front and back connected to the right take-off?

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    Re: Braided lines causing squishy brakes?

    symptoms suggest master cyl faulty

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    Racer Decade Plus User Adam B's Avatar

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    Re: Braided lines causing squishy brakes?

    yeah, might look into the m/c first, and put 5.1 fluid in whilst i'm at it, then go from there.

    annoying as i bought it brand new from ford, but it was ages before i built it up

    My Project... Fiesta D-TEC

  8. #8
    Racer Decade Plus User Adam B's Avatar

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    Re: Braided lines causing squishy brakes?

    Quote Originally Posted by DGO View Post
    Also if you have multiple take-offs from them master cylinder i.e. for dual circuit brakes, are you sure you have front and back connected to the right take-off?
    yeah, i made sure of this, the effectiveness of the brakes has not really been an issue, its just the interesting pedal activities.

    My Project... Fiesta D-TEC

  9. #9
    Racer Decade Plus User Adam B's Avatar

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    Re: Braided lines causing squishy brakes?

    Quote Originally Posted by andypipe View Post
    Have you run the pipes in a different position. Suffered with spongy pedal for 20 years and found the problem was the pipework was higher than the master cylinders
    the master cylinder is the highest point

    My Project... Fiesta D-TEC

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