rear break sticks?

Discussion in 'Touring Models' started by convict, Apr 13, 2009.

  1. convict

    convict New Member

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    i have a 1977 FLH electra-glide and the rear break sticks. i believe it has something to do with the caliper-----does anyone have any idea?
     
  2. glider

    glider Veteran Member

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    Clean or rebuild the caliper is about the only choices.
     
  3. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    You can try flushing the system by pumping out a bunch of brake fluid and replacing what's in there now, but likely you will have to rebuild the caliper and master cylinder. The master has a relief port in it that if plugged will cause the brake to stick. If you have never rebuilt those brakes, it is time. I would suggest rear and fronts (I assume you have duals in the front).

    TQ
     
  4. glider

    glider Veteran Member

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  5. hobo55

    hobo55 Active Member

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    Didn't get the wrong brake fluid in there did you ? Dot 3 will bind up a dot 5.
     
  6. 3wVo

    3wVo Banned

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    I hope this post is not too long for the group...

    Rubber has memory. They make a caliper seal and it is called a, Quad seal. To look at this o-ring is that it has 4 square sides. If I were to machine out a groove, my 3 angles are square to the round floor and the two walls that were machined out into a 3 sided groove that is flat on all 3 sides being this is a quad seal with 4 sides.

    I now install my round caliper piston and I have completed 4 sides of that quad seal. For the seal to work, we need that groove as clean as a whistle. If I brake and can run the brake discs cherry hot like a NASCAR short track car, do you think it would boil the brake fluid? I think it would boil.

    OK, so if it boils, what is displaced inside the bubble. Did you say water vapor? You are correct. If water is in the system; it will cause the water to mix with the, 'dot-pick a number' is that oil will bubble too. So this is more the generic as to how that caliper is hanging up after a rebuild or a flush.

    Getting back to grooves and memory, water is heavier than oil. We now have followed the water to the lowest point of the brake system. That is where the brake q-ring lays. Water finds its way under that rubber; which causes by the water vapor to heat and dry to a crusty gamook.
    It then crystallizes, causes the seal to be pushed up against the piston and locks the piston from moving eventually.

    This is a twofold happening. One, that the groove is compromised from the seal to move back into the groove and as it does, it pulls the piston ever so slightly back. Remember, the piston is pulled back as far as the rubber can fit back into that groove.
    We know the piston will move ever so forward as the pads wear. That barrel will still be pulled back as long as that groove is clean of crystal residue buildup.

    In conclusion:

    1. If that wheel drags after a flushing, it is the buildup under the quad-ring.
    2. If you rebuilt the caliper but did not pull the quad ring out of the groove, your wheel might drag.
    3. If you sand or remove the machined finish from both the groove or where the piston rests, you may have compromised a better brake feel if you left the finish alone and just wiped with a paper towel and call it a day.
    4. The groove has to be perfectly clean and brake fluid will show that trail of white powder when the brake clean dries. Chase all that is in the groove where you see anything you left behind... Try to get every bit out.
    5. The rest is routine feed and bleed. But the groove and the drag are the trick to cleaning a caliper back in service is buy a new quad ring and call it a night. She is good to go is I'd even ride your bike now. :newsmile036:
     
  7. NEWHD74FAN

    NEWHD74FAN Experienced Member Retired Moderators

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    3wvo, good post...simply put, do not try polish or use abrasives on caliper bore or piston...micro-scratches means 10,000th of an inch mirror finish is compromised. Clean all parts especially the grooves with non-chlorinated Brakleen over a rag, carefully flush and blow dry several times only...again do not scratch or damage items with metal tools, polishes or rags of any kind, even paper towels may deposit lint and will freeze up the works! Assemble all parts with proper brake fluid only and you should be good to go.

    Go to tech info for specifics on Gliders' quick caliper clean and maintenance approach, it works as "normal service" routine. Use the above only if you are into your 2nd or 3rd caliper maintenance after you have done Glider' recommended routine AND you feel that only complete caliper disassemby/inspection/rebuild is your final option. Don't forget to use at the very end, the thin layer of high temp grease on the pins ONLY. And check all brakes actuate properly after any maintenance and bleeding/changing brake fluid routines by pressing brake controls and trying to move the bike in driveway as aggressively as possible, compressing the front fork and brakes hold after all is assembled, you do not want to do initial testing on public roads and experience problems.
     
    Last edited: Apr 13, 2009