Brake locking up

Discussion in 'Other Service and Maintenance' started by penmaker, Feb 24, 2009.

  1. penmaker

    penmaker New Member

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    Trying to figure out why my rear brake locks up. If the bike sits for a few days the rear brake locks up when I take it out on the road and first use it. I can bleed it and it will work fine after that. I've blown the lines out for trash, use dot 5 fluid, and rebuilt the master cylinder.
     
  2. glider

    glider Veteran Member

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  3. penmaker

    penmaker New Member

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    Think I should go back to dot 4 seeing how it's and older bike then. I'll replace the seals and see what that does for me. Thanks for the advice.
     
  4. glider

    glider Veteran Member

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    Try to ascertain what was in there. It would require dis assembly and cleaning , seals replaced then the DOT 4 installed if you go that route.
     
  5. jel123

    jel123 Active Member

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    Before you start tearing into things i had a had a problem like that on my pm rear brake and after alot of work found it to be a little vend hole in the master with the heat it had no way to vent there fore it applied pressure to the rear brakes,jel
     
  6. dangerdan

    dangerdan Junior Member

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    I just checked the PDF fille on 1966-1984 shovelhead manual

    The front of the manual says the following
    Brake fluid thru 1975 DOT-3
    Brake fluid 1975 on DOT-5

    The Brake section for that manual differs slightly. See attached file

    I knew those manuals would come in handy

    Thanks to Speed for allowing us to download and thanks to those who contributed
     

    Attached Files:

  7. penmaker

    penmaker New Member

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    yep your right, my manuals say to use dot 5 , seeing as how we're suppose to get snow this weekend it'll be a good time to dig into it and see what's going on, thanks for the help everyone.
     
  8. NEWHD74FAN

    NEWHD74FAN Experienced Member Retired Moderators

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    You may also want inspect and clean and inspect the rear caliper and verify guide pins are clean, checking for corrosion or wear of the hardened contact surfaces, relube them with high temp grease. Also before removing the caliper to inspect, use plain water clean the loose road grime first and dry the cleaned unit carefully.

    Use a shoe lace dipped in brake fluid to clean the outside of the exposed pistons prior to disassembly, so you do not drive any debris into the bores when spreading the pads/getting them off. The calipers should center directly over the rotor and only a light amount of drag, (swish sound from the pads contacting the rotors) if you are able to elevate bike wheel without interference.

    And finally, after any brake work, bleed them in case you got air into the hydralic system. Check before test ride by rolling the bike firmly and make sure braking is crisp, engaging and releasing properly. Don't want to be on the road and not have them stop or lockup.
     
    Last edited: Mar 1, 2009