Front Brakes Locking 1150GS ABS 2000

[marcopol]

Some weeks ago I was filtering very slowly in traffic and executed near enough a full lock to the left. I noticed that the front brake started to come on on its own, not enough to stop the bike but enough to notice that the pads were staring to engage. I checked to see if any of the brake lines were under stress or were being stretched when the handlebars were turned in any direction and they are all Ok. Incidentally I do not have any bar risers fitted.
Today in a straight line the pads would not disengage when I applied the front brakes and then let go of the front brake lever. The pressure at the lever was rock hard indicating that the pistons were fully extended.They eventually released themselves enough for me to move onlyafter they cooled down. I took off the front calipers and the pads are OK and there is no obvious sign of crud around the pistons.
The obvious problem would suggest that the pistons are sticking and need to be cleaned but why did this happen so quickly. Before I strip and clean the calipers, which is a pain in the Ass, could it be the valve in the front brake resevoir sticking?
Anyone come across this problem before?

 

[Stewart H]

It could be a master cylinder piston not returning all of the way, or perhaps even a brake hose collapsing internally and acting like a one way valve, if you can make it repeat the symptom try loosening a bleed nipple on the caliper when it is actually doing it, if you get a stream of brake fluid then you will know that the problem is hydraulic rather than sticking pistons in the caliper.
Stewart

 

[Steptoe]

or perhaps even a brake hose collapsing internally and acting like a one way valve,

This seems to be a common problem lately. My loan bike did it recently and i know Rab had the same problem couple of weeks ago.

Perhaps it's an age thing.

 

[Decster]

What? Like repeating yourself?

i posted a comment too and then saw it was corrected so deleted it not to look stoopid

 

[marcopol]

perhaps even a brake hose collapsing internally and acting like a one way valve,
Stewart

Are the hoses not single skinned ?, or are you suggesting that they are effectively hoses within hoses?

 

[John Armstrong]

Had a Peugot 205 where the hose collapsed and didn't let all the brake pressure off. Took an age to find, but the bleeding after applying the brakes finally found it.

 

[Stewart H]

Are the hoses not single skinned ?, or are you suggesting that they are effectively hoses within hoses?

My standard one split to reveal a mesh or some kind under the outer rubber beneath this there was more rubber, I did not dissect it further. but the problem is certainly not unknown it the car world too.

Stewart

 

[robmack]

As steppers has said, i had a problem with the left hand caliper on my 2000 1150 GS with the Brembo brakes, the left hand inside pistons siezed solid.
Managed to free off the pistons by pumping them out with an old master cylinder that i use.
Also noticed that the inside of the flexi hoses had broken down and there were small pieces of rubber blocking the bleed nipples when i tried to bleed the system it would not bleed and the brake lever was solid.
Changed the brake lines with Goodridge hoses and bled no probs.
Still got a leaking caliper though

Rab

 

[fatbaldbob]

I too have suffered thus problem and previously posted about it, 04 GSA Servo ABS, the braking applied was sufficient to stop the bikeAgain it was only on the left side which seems to be becoming a common theme? Upon checking the caliper the pistons seemed free but the pads where sticking on the pins and creating a slight drag on the disc, it was suggested by a member on the forum that this slight drag on the discs could cause heat to build up on the caliper, heating the fluid causing an expansion and therefore pushing the pistons out and applying the brakes Anyway I cleaned off the pins lubed them up and it seemed ok. Then I sold it and brought a GS800 and have had no problems since

 

[marcopol]

Front Brake

Right I eventually got around to taking a closer look at the front brakes.
The pistons are not sticking, because as soon as I open the bleed nipples on both sides the brakes release themselves. Looks like I have no other option but to replace all the front hoses ?

M

 

[Stewart H]

I recently had a problem with the front brake lever sticking on an 1150 of similar vintage to yours, we cured that one by stripping cleaning and lubricating it, the lever was just not returning to the at rest position and the brake light was staying on too, worth a look before you get your wallet too dented

Stewart

 

[marcopol]

Pads

No the lever is OK.