1994 Sportster 883 rear brake problems

Discussion in 'Wheels' started by morpheus1975, Oct 24, 2013.

  1. morpheus1975

    morpheus1975 New Member

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    I have a 1993 Harley Davidson sportster 883 hugger. I had a flat on the rear, so i changed the tire.After i done this, I had no rear brakes. So with my bike being 20 years old, I completely redone the rear brake system. I installed a new caliber with pads, master cylinder rebuild kit and a new braided brake line. I used a Mityvac to pressure bleed them and i had good pedal until i got to going at a good rate of speed, then i got to apply the rear brakes, no pedal. I would have to pump the rear brakes to get a pedal to stop the bike. So i came back and hand bled them. Same thing happened as before,good pedal when stopped and first taking off, but at a good rate of speed, no pedal. I have the clymer's and the factory service manual for my sportster. I used only dot 5 brake fluid. After spending 200 in parts and 140 in manuals, i still have the same problem
     
  2. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

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    If there are no leaks in the system then I would suspect the master cylinder to be the problem area with the seals folding back when hot or the brake pedal not allowing the MC piston to fully return
    So try adjusting the pedal so that it is not hard against anything when cold
    If the brake rotor was very warped it may push the calliper piston back in and a few pumps of the brake would be required to get it back to the current working area

    Brian
     
  3. morpheus1975

    morpheus1975 New Member

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    So, the master cylinder could be bad even with the rebuild kit that includes a new piston and seals?
     
  4. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

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    I think on yours the rebuild kit has a new cylinder and piston with seals and just because it is new does not mean it is good although I would suspect that a new master cylinder kit is good
    But if all is well when bike is standing still possibly an issue with movement or heat expansion

    Brian
     
  5. morpheus1975

    morpheus1975 New Member

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    So it seems like it is time for a 75 a hour trip to the local Harley Davidson shop
     
  6. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

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    I did have a similar sort of issue on BMW I was restoring about 10 years back I and a friend cut the captive nuts off the frame and welded replacements on however the placement of the new nuts was not exactly the same as the old and when the master cylinder was mounted to the frame it was about 1/2 mm closer to the brake pedal when the pedal was fully up the piston inside the master cylinder was not fully retracted and did not fully clear the inlet hole in the reservoir so fluid did not flow properly to the front of the piston
    A wee adjustment of the operating rod between the brake pedal and master cylinder cured my problem
    There should be some adjustment available on yours you will need to pull the cotter pin from the base of the pedal to adjust the length of the rod shorter by a couple of turns and try break again

    However all this is just thoughts I am having without the ability to at first hand examine the problem on your bike

    Brian
     
  7. Jack Klarich

    Jack Klarich Expert Member

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    To test the master, you can clamp off the rear brake hose, 1 pump you should have full pressure, if you do not you have a problem internal in the master, be it a rolled over cup or a blocked compensating port