Brake Problems

Discussion in 'Wheels' started by Stanfom, Aug 16, 2011.

  1. Stanfom

    Stanfom New Member

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    I have a 2003 Ultra Classic. Since the time the bike was new, the rear brake always goes soft and fades in altitude. Pads are fine, rotor is good and has been bled over and over. After bleeding it feels great, as soon as I get into high altitudes it goes soft again. Anyone one with similar problems or suggestions ?
    Thanks in advance...
     
  2. Jack Klarich

    Jack Klarich Expert Member Contributor

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    Bypassing master cylinder, rebuild or replace it:s
     
  3. glider

    glider Veteran Member

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    I agree with Jack here. If the piston in the MC doesn't hold the pressure you will have exactly what you are experiencing.
     
  4. R. Lewis

    R. Lewis Senior Member Retired Moderators

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    Just asking here cause I dont know -- but if MC was bad/not holding wouldnt it do the same in the flats as well?
     
  5. Jack Klarich

    Jack Klarich Expert Member Contributor

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    Yes and no, when the pistons by pass there will be little or no pressure as the fluid by passes the rubber seals, one sure way to test this is pinch off the brake hose and pump the brakes, if the master is by passing you will have a soft pedal, this happens alot more with dot 5 in my experience, Hey Randy good to see you:s
     
  6. R. Lewis

    R. Lewis Senior Member Retired Moderators

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    Thanks for the info Jack. I'm still hangin on!!!!:s
     
  7. vaughank

    vaughank New Member

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    maybe braided lines would help. or a m/c rebuild might be in order.
     
  8. Jack Klarich

    Jack Klarich Expert Member Contributor

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    Good deal Randy, I go to the bone crusher Wednesday, More bad news I bet Oh Well, least we all have the Forum to help us through the tough times RIGHT:s
     
  9. Jack Klarich

    Jack Klarich Expert Member Contributor

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    A collapsed brake hose will cause problems also, usually a hard pedal from my experiences , braided is a better choice:s
     
  10. glider

    glider Veteran Member

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    From a document that Jack just posted.

    Master Cylinder Bypass Test
    If you suspect an internal leak in the master cylinder, perform the
    master cylinder bypass test. If, while the brake pedal is being
    pressed slowly, the BRAKE warning lamp comes on, but there is no
    indication of loss of reservoir fluid, the master cylinder may have an
    internal leak.
    Check the brake fluid level in the reservoirs and add fluid as
    necessary. Observe the reservoir. Push the pedal all the way down
    one stroke and release it. If the level of fluid in the reservoir rises
    while the pedal is being applied and falls when the pedal is released,
    the brake fluid is bypassing the pistons. The master cylinder should
    be repaired or replaced.
    As a further check, hold the pedal down firmly for two minutes. If the
    pedal feels firm for the first minute then fades, the brake fluid is
    bypassing the pistons.