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Thread: 1978 R80 Brushes Question

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  1. #1
    Nick Kennedy
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    Nov 2011
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    Telluride Colorado
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    1978 R80 Brushes Question

    Hi Gents
    My Gen light flashed on today for just a second. I took a look at my brushes and they are about 1/8th -3/16th into the holder.
    The bike has 44,500 miles. Are they shot?
    When the brushes are new, are they in the holder, flush or extended out?
    How difficult are they to change out? Is the soldering precise?
    Thanks in Advance
    Nick Kennedy

  2. #2
    Sir Darby Darryl Cainey's Avatar
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    My 77RS had 450,000 miles on when I replaced my brushes so I doubt yours are worn out.

    If so Motorrad Elekrik has solderless brushes.

    http://www.motoelekt.com/
    Ambassador BMW MOA Ontario Canada
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    1977 R100RS, (Retired) 1993 R100GS (just getting started)

  3. #3
    Registered User
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    I bought new brushes, but just pushed down on the old ones with a pencil. They weren't making full contact. That was after some 125,000 miles, so I doubt that yours are worn away. They've charged fine since I did that about 6 years ago.

  4. #4
    MOA #24991 Pauls1150's Avatar
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    IF the gen light came on because of the brushes, you may just need to clean up the contact area; since 1978, you may have some corrosion or just carbon buildup down there.

  5. #5
    Registered User
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    Dec 2012
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    If they are like brushes on an electric motor, with some sort of a spring pushing them down, it could be just a build up of crud on the SIDES of the brushes.

    I just take a piece of wet-or-dry paper, and sand then lightly on the sides and edges and then make sure they float up and down easily for the spring to push then against the rotor.

    If it doesn't then and they are too short, replace them.

    Also, be sure to clean the contact surface by lightly sanding as well. One thing that also helps is the use of contact cleaner - available at most auto type stores or Grainger, McMaster-Carr or any electrical shop/store like Graybar.

    The contact cleaner is designed to be used while an electric motor is running - no threat of fire. Cleans somewhat the commutator as well.

  6. #6
    Nick Kennedy
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    Nov 2011
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    Telluride Colorado
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    Thanks for the advice you guys, I will clean up the area, after 35 years young there is bound to be some funk in there!

    But I am still curious...How low can they go? Is there a color difference at the max wear point?
    Cheers
    Nick Kennedy

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