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Thread: My Front Brake Lever is Sticking Slightly Keeping Brake Light On - Why?

  1. #1

    My Front Brake Lever is Sticking Slightly Keeping Brake Light On - Why?

    Brakes have been bled a few months ago and new fluid added on my '86 R80. Reservoir in good shape. Fluid
    honey-colored. The front brake lever was staying ever so slightly engaged before the bleed and
    cleared-up afterwards. Now, some several months later, the front brake lever is again staying
    just slightly engaged so the brake light is staying lit. I can ride along and keep pressure on the
    brake lever forcing it fully "out" if you will, but I know that's not a proper fix. Any ideas why I'm having
    this problem. Master cylinder needs rebuilding?
    Last edited by captainmako21; 04-05-2014 at 09:58 AM.

  2. #2
    Go with the low hanging fruit first -- is the pivot pin and perch greased? After that, it's got to be something in the hydraulic system, MC or caliper or (unlikely) some blockage in the line. I'd pull the caliper and see if the pads push in easily.
    '61 Clubman's Gold Star, '13 690 Duke, '13 Daytona 675R, '14 Street Triple R, '17 1290 GT (gone but not forgotten: '76 R75/6, '84 R100, '76 R90S)

  3. #3
    If cleaning & lubing the lever doesn't get you anywhere, you're going to end up cleaning out the master cylinder. I rarely bother these days; in my experience they never feel the same after the surface finish has been compromised. $200 usually gets you a brand new one.
    Anton Largiader 72724
    Tech articles
    Virginia Motorrad Werkstatt BMW motorcycle service and repair in central Virginia

  4. #4
    Thanks for the help everyone. I just took it out for a couple hour ride and it
    still experiencing the problem. Will probably bit the bullet like you suggest Anton
    and get a replacement. Thanks again.

  5. #5
    Registered User lmo1131's Avatar
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    Hey, when I yank on my front brake lever a cable actuates the shoes down below, and the front brake light switch is actuated directly by the lever.

    Is the R80 switch hydraulically actuated? From the microfiche it looks like a discrete, replaceable, mechanical switch [#24] If that is the case, maybe you could back the switch out a quarter turn, or so, to pull the plunger away from the lever? A drop of blue loctite would keep it from rotating.



    "It is what you discover, after you know it all, that counts." _ John Wooden
    Lew Morris
    1973 R75/5 - original owner
    1963 Dnepr

  6. #6
    On the Road
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    Front Brake light staying on.

    Quote Originally Posted by captainmako21 View Post
    Thanks for the help everyone. I just took it out for a couple hour ride and it
    still experiencing the problem. Will probably bit the bullet like you suggest Anton
    and get a replacement. Thanks again.
    That happened to me. I simply removed the Master Cylender Piston, cleaned the cylinder and piston reinstalled and now it works like new

  7. #7

    Smile

    Quote Originally Posted by lmo1131 View Post
    Hey, when I yank on my front brake lever a cable actuates the shoes down below, and the front brake light switch is actuated directly by the lever.

    Is the R80 switch hydraulically actuated? From the microfiche it looks like a discrete, replaceable, mechanical switch [#24] If that is the case, maybe you could back the switch out a quarter turn, or so, to pull the plunger away from the lever? A drop of blue loctite would keep it from rotating.



    I will research the switch Imo1131. Sure would be a lot less $$$ if it were only the switch....... Thanks and cheers.

  8. #8
    Day Dreaming ... happy wanderer's Avatar
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    I had the same problem on same type of switch. Removed the switch, sprayed it generously with WD40, then blew it out as best I could with compressed air and re-installed it. No problems since and that was a couple of years ago. I think dust and grunge can build up in there and cause it to stick.
    MJM - BeeCeeBeemers Motorcycle Club Vancouver B.C.
    '81 R80G/S, '82 R100RS, '00 R1100RT

  9. #9
    Registered User lmo1131's Avatar
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    I think dust and grunge can build up in there and cause it to stick.


    I didn't even think of the "stiction" element. You're right (I'll bet). From the clearance around the plunger (pictured above) it sure looks like it could get packed with crud; 28 years should have been about long enough.

    Here's the P/N for the switch assembly pictured > 61 31 1 459 569

    There's also a service bulletin that addresses over-tightening. > http://www.maxbmwmotorcycles.com/fic...11459569_1.pdf
    "It is what you discover, after you know it all, that counts." _ John Wooden
    Lew Morris
    1973 R75/5 - original owner
    1963 Dnepr

  10. #10
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    If the Break lever returns as far as it can and brake light does not go out it would be the switch. But if you can push the lever as far as it will return it is crude around the piston.( That is to say if the break light go's out it is crud around the piston at the rear seal. Be sure the return hole in the reservoir is not blocked.

  11. #11
    Registered User Anyname's Avatar
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    I had the same issue on my 86 and it was just the pivot pin needing cleaning and lubrication.
    BMW R bike rider, horizontally opposed to everything...

  12. #12

    Update

    OK - unscrewed the brake switch and it tests fine. Very clean for an '86 bike. Cleaned and lubed and
    cleaned and lubed the internals of the lever case, if you will. Cleaned lever. Cleaned the screw and wavy washer
    and even the nut. Put it all back together and while the lever is not as "wiggly" it still does not seat fully to the forward
    position and hence, the brake light kicks on again.

    Question: Could a new brake lever remedy the problem possible? The fitment section of the lever is worn, but have
    no way to determine how much metal has been degraded from use.

    Or: You folks think it's time to get into the piston and m/c?

    Lever is about $50 from Max BMW, btw.

  13. #13
    A new MC comes with a new lever.
    Anton Largiader 72724
    Tech articles
    Virginia Motorrad Werkstatt BMW motorcycle service and repair in central Virginia

  14. #14
    Quote Originally Posted by AntonLargiader View Post
    A new MC comes with a new lever.
    Thanks Anton. I was thinking about just jamming a racquetball between the brake lever and the handlebar.
    Suppose that might be counter-productive if I ever need to stop.

  15. #15
    #4869 DennisDarrow's Avatar
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    Anton........THANKS for what you do for us..................For me, I would follow the excellent advice that many have given. One can clean out the MC and put in a kit after a bit of sanding/polishing the bore........One can send of the MC to several very competent folks to rebuild.........or buy a new MC.

    It really does seem a waste to have to maintain these master cylinders like we have to; but yours, and on my 83 RT are prime examples of what happens if it isn't done often enough. The annual bleeding and flushing out the old fluid with new.....NEW, not left over from last year, really does keep this from happening.........Bite the bullet Bud and do it right...........God bless.........Dennis

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