Front brake only stopped working

[scud]

02 1150 GS (ABS) with 66,000 miles.

Got up this morning to go to work and found out, as I pulled up to the main road, that the front brake lever went all the way to the handle without any braking effect whatsoever!

It started fine, with no warning lights flickering or showing, I haven't changed any pads or anything even near recently and there's no fluid that I can see on the floor or the bike. The fluid level in the reservoir shows normal (albeit near the minimum). I have used the bike every day and up until now, it was not indicating a problem in any way. The rear brake works fine.

Any ideas? I really don't want a mega bill for it at the moment so your help will be greatly appreciated!

 

[John Armstrong]

Have you checked the brake fluid level from the ABS controller to the brake? IIRC you can happily drain this circuit when trying to bleed the brakes Not a clue on how to check it apart from disconnecting the pipe or open the bleed bleed nipple

 

[boxer]

Seal in master cylinder gone

 

[Steptoe]

Have you checked the brake fluid level from the ABS controller to the brake? IIRC you can happily drain this circuit when trying to bleed the brakes Not a clue on how to check it apart from disconnecting the pipe or open the bleed bleed nipple

This is only relevent if you've servo brakes.

Are your brakes servo ??? you don't say

 

[scud]

Typical to forget something....

This is only relevent if you've servo brakes.

Are your brakes servo ??? you don't say

Yes they are servo....

I've also seen a master cylinder repair kit for £38 +p&p. do you do them Steptoe? is it a straight forward job? it's not listed at all in the manual I've got

 

[Pukmeister]

Hi Scud,
I'll assume you have little knowledge of the servo systems so apologies if this is sucking eggs. Can you hear the servo pump whine when you operate the hand lever? If not then you either have an electrical fault or else the pump may have failed either electrically or hydraulically which may prove expensive. If the servo pump fails, you should have "residual braking" which is pretty weak by comparison with servo brakes but gets you stopped through using full lever travel to generate hydraulic force. If you had no brakes at all it sounds like either a seal failure or air in the system somewhere.

The fluid in the reservoir on the handlebars is like a pilot operating system for the brakes and not the full braking system, using the brake lever causes the servo to operate and do the work for you. The electrical ABS/Servo pump has its own internal reservoir under the fuel tank which runs the front/rear brake circuits individually. Replenishing the fluid in the handlebar reservoir doesn't replenish the fluid in the servo pump/brake circuit. This is usually done by a dealer as it can be difficult to fill the servo unit and eliminate air, they usually use a funnel and a screw on length of hose to elevate the filler well above the height of the servo pump.

If your front brakes have air in the system, there is a dedicated procedure for bleeding them and refilling the system. If I can find a link to an article on it I will post it here for you, though its usually best left to a dealer unless you are a confident home mechanic.

EDIT: Heres the link, enjoy the reading....

http://www.gsrider.co.uk/service_abs3.pdf