Bmw R100/7 braking failure light issues

Discussion in 'Old's Cool' started by sake_w650, Feb 21, 2011.

  1. sake_w650

    sake_w650 Adventurer

    Joined:
    Aug 2, 2010
    Oddometer:
    10
    Hi all airhead enthusiasts,

    Guess this is the best place to get technical help and advice. My R100/7 brake failure light flickers and keeps coming on and sometimes the light appears and it does not go away. It seems to be due to the front brakes cos sometimes when i squueze the front brake levers, the brake failure lights dissapears and evertything is back to normal.
    My brakes seem to be working fine but am just bothered by the red light when i'm riding and i believe i read somewhere it could be due to some leakage or cracked brake hoses.

    Any advice would be greatly appreciated, thanks!!
    #1
  2. fishkens

    fishkens Long timer

    Joined:
    Nov 14, 2009
    Oddometer:
    5,252
    Location:
    Seattle, WA
    Does your bike still have the stock master cylinder under the tank? Have you inspected it for leaks or fluid level? That's a starting point.
    #2
  3. Hawk Medicine

    Hawk Medicine Coyote's Brother

    Joined:
    Jun 8, 2008
    Oddometer:
    3,304
    Location:
    NOR CAL
    Check the master Cyl for fluid level and leaks
    Check the pads for thickness
    Check the MC pressure switch for loose connections and proper operation.

    When was the last time you serviced your brake system? :wink:
    #3
  4. Box'a'bits

    Box'a'bits In need of repair

    Joined:
    Sep 26, 2008
    Oddometer:
    2,505
    Location:
    Wellington, New Zealand
    The original m/cylinder has a float in it to make sure you don't run out of brake fluid. This operates a switch. Either A. the float is getting old & is sinking, or B. you need to check the brake fluid levels.

    I have disconnected mine.
    #4
  5. wirewrkr

    wirewrkr the thread-killer

    Joined:
    May 23, 2008
    Oddometer:
    4,295
    Location:
    HIGH desert
    Yes, as was stated earlier, on the under the tank models, that light is only for brake fluid level. Period.
    One of the things that happens as your pads wear is the fluid level drops because the pads and pistons are moving in towards the rotor. You need to pull the tank and check the fluid level right away before you lose your brakes or get air into the system.
    In 81 when they moved the master cylinder to the handlebar that light was eliminated from the cluster as it was no longer needed.
    #5
  6. supershaft

    supershaft because I can

    Joined:
    Sep 9, 2010
    Oddometer:
    9,116
    Location:
    San Francisco Bay area
    I thought someone else would mention it but so far no one has. I have seen plenty a brake light come on for the wires on top of the cap shorting out against the tank.
    #6
  7. sake_w650

    sake_w650 Adventurer

    Joined:
    Aug 2, 2010
    Oddometer:
    10
    Thanks guys for all the overwhelming assistance and help. Yes, mine comes with the stock, under the tank brake fluid cylinder. Wanted to keep it true to original but have been playing with the thought of changing the brake fluid to the later models located on the handlebar so that they can be easily serviced. I heard its better too in terms of braking power, wonder how true is that?

    Anyway, the brake failure light appeared initially due to the lack of brake fluid but I have since topped it up and periodically checked the brake fluid level, wonder why the light reappears again though there's sufficient brake fluid? Perhaps its a good idea to bleed the brakes? Cos i just topped up the brake fluid without bleeding the brakes? Doubt its due to leakage cos the brake cylinder's had been recently replaced about 4000 miles ago.

    Really grateful for the feedback guys!! :clap
    #7