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Old 02-21-2011, 05:29 PM   #1
sake_w650 OP
Joined: Aug 2010
Oddometer: 10
Bmw R100/7 braking failure light issues

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!!
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Old 02-21-2011, 05:36 PM   #2
Joined: Nov 2009
Location: Seattle, WA
Oddometer: 5,163
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.
Forging ahead, down a false trail.
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Old 02-21-2011, 07:22 PM   #3
Hawk Medicine
Coyote's Brother
Joined: Jun 2008
Location: NOR CAL
Oddometer: 3,304
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?

Hate rots the pocket that carries it.
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Old 02-21-2011, 08:24 PM   #4
In need of repair
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Joined: Sep 2008
Location: Wellington, New Zealand
Oddometer: 2,393
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.
My '91 R100GS thread is here
My Ride photos are here

It's just better when there's twins involved....
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Old 02-22-2011, 12:17 AM   #5
the thread-killer
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Joined: May 2008
Location: HIGH desert
Oddometer: 4,295
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.
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Old 02-22-2011, 09:05 AM   #6
because I can
Joined: Sep 2010
Location: San Francisco Bay area
Oddometer: 9,116
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.
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Old 02-22-2011, 09:28 AM   #7
sake_w650 OP
Joined: Aug 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!!
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