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Thread: Sudden brake failure and then came back?

  1. #11
    Join Date
    Mar 2013
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    Quote Originally Posted by Mjolinor View Post
    They do have independent brakes and "all the way down" should not be possible even if something fails.

    I had a weird one where sometimes the servo didn't work. This was a hole in the vacuum to the wastegate so when the wastegate was told to open I losta ll vacuum. This meant that the first time the brakes were applied if the wastegate was open then it worked properly but once the vacuum on the servo side of the one way valve ahd been used it was not replenished until the wastegate shut again.
    Hi sorry it might not of went completely to the floor but it went to the usual distance but with no resistance. It's been fine since but I've only driven it around the block a few times quite slowly.

  2. #12
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    Apr 2009
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    Was there any sign of the ABS intervening? Say, a diesel spill on the road? Did the pedal pulsate under your foot?

  3. #13
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    Quote Originally Posted by pinger View Post
    Was there any sign of the ABS intervening? Say, a diesel spill on the road? Did the pedal pulsate under your foot?
    Hi, there was nothing like that it was more of just a soft sponge feeling that had no resistance and no real effect on the braking.

  4. #14
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    Could be a seal failure. With the car stationary but with the engine running (for the servo) absolutely stand on the brake pedal. I mean torture it. And see what happens. Have a good look around the car for any leaks especially if the reservoir level has dropped. Include along the sills (where the pipes are hidden and are prone to corrode). Obviously around the wheels but (esp rear) leaked fluid can take time to appear - but reservoir level is key. However, a master cylinder leak will not necessarily show as an external leak.

    If the pedal held up, then if you can find a safe stretch of road, build up some speed and stand them (more torture) and see what happens. Repeat as often as necessary to provoke the fault or restore your confidence. If there's a mechanical fault, it should show itself. Take care if you decide to do this.

  5. #15
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    Another possibility is that there was a seized piston in either a caliper or rear wheel cylinder which decided to free itself hence the pedal going from underneath your foot but which the brakes subsequently recovered from. Or some other component gave way (I once had brake failure when an adjuster failed). If the car hasn't had brake work for a while, maybe time for a check-over.

    As stated by another, complete brake failure is very rare. The circuits are split precisely to prevent it.

  6. #16
    Join Date
    Mar 2008
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    if you press the brake a few times when stopped it should get harder and harder to press and the pedal travel get less and less

    JJ

    www.forfour.co.uk - forfour technical forum
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  7. #17
    Join Date
    Jan 2011
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    in the first instance , have the brake fluid flushed through and changed.
    You're so money supermarket and you don't even know it!

  8. #18
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    The car also has a parking brake that is applied mechanically. Did that one fail too?
    Drives a Smart Cdi - 65 to 85 MPG

  9. #19
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    Quote Originally Posted by reinaldo_is_spam View Post
    in the first instance , have the brake fluid flushed through and changed.
    Nope. Arbitrarily throwing things at a problem rarely solves it and will very likely destroy evidence as to what is the problem.

    Define the problem and only then replace what is necessary. Besides which, bleeding brakes with ABS is a PITA and can easily introduce false problems - unless done by opening the ABS valves which unduly stresses the solenoids.

  10. #20
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    Can't agree more with last poster.
    Drives a Smart Cdi - 65 to 85 MPG

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