front brake comes on its self!

[thesitetoremember]

The bike is an April 08 GSA with ABS. 7000 miles with it's 6k service carried out last month.

Last Monday I was riding to work, my usual route, on a 60mph country road when I braked to slow behind a car. I then pulled out to overtake and the bike did not go as swiftly as I expected because one of the front brakes had come on (one disc roasting hot, other cold).

I stopped, had a look, let the disc cool down and after about 1 minute he brake had freed off again. The disc was very blue...

The same happened again on Thursday of last week but this time the brake 'freed' its self whilst on the move.

Tonight on the way home from work, accellerating from a 30 up to 60 (ish) and the front brakes come on again. I stop bike at side of road (without having to apply more brake). At this point I try to move the bike back and forth with my legs and I cant but as soon as I turn ignition off the brake frees itsself???

I do a 20 mile commute and it only seems to happen when I'm at speed.

I will be phoning the dealer tomorrow AM but would like to know if anyone has experienced anything similar.

for info I've checked obvious things like front brake lever fouling etc but nothing to suggest I'm inadvertantly applying brakes.

Your comments please...

 

[cookie]

sounds like a sticking piston.

if it was a fault further upstream, both discs would get hot.

 

[(RIP) ugg]

but as soon as I turn ignition off the brake frees itsself???


ABS fault, why would stopping the ignition make the piston release?

ugg

 

[cookie]

but as soon as I turn ignition off the brake frees itsself???


ABS fault, why would stopping the ignition make the piston release?

ugg

i thought the ignition thing was probably coincidence

if the ABS/servo unit was creating the problem, both calipers would activate, surely? there's only one hose feeding the front brakes i'd have thought (obviously it must split above the calipers).

 

[Pukmeister]

Check the brake lever isn't touching inside the handguard. With the igniton on but the engine not running, try the front brake then release it and then try pushing the bike to see if it has stuck again. Remove and clean your brake calipers if you are mechanically competent and see if that frees any sticking pistons.

Personally if it were my bike I'd be off to see the dealer for a fix under warranty of my 2008 bike and a replacement of the blued front disk as it is probably warped and shagged by now. They have the diagnostic equipment to check the ABS system for faults and also they should test ride it and record the work so that if you have any other faults later on, there is an audit trail that may help you if you need help/warranty claims from BMW in future.

 

[thesitetoremember]

Thanks for the replies.

I've checked the lever against the handguard and there is no fouling.

I've been running bikes through winter for about 8 years and have been used to having to remove / clean the calipers every once in a while (although have not done this on the GS). My old Yamaha was very prone to the pistons sticking but the symptoms felt very different. Once a piston became sticky in the caliper then you could easily replicate the problem by simply applying the brake and you could feel that the brake was sticking. I then had no option but to spend an evening in the garage removing and cleaning the caliper / pistons.

The 3 instances I've had with the BMW the brakes 'free' off without any real effort at all from me.

As part of the maintenance schedule on my old road car, a Subaru Impreza, a brake caliper clean and rebuild was done. Does anyone know if it's part of the BMW service schedule?

I'll get it booked in to be looked at.

 

[LiquidLAN]

Check the brake lever isn't touching inside the handguard.

Personally if it were my bike I'd be off to see the dealer for a fix under warranty of my 2008 bike and a replacement of the blued front disk as it is probably warped and shagged by now. They have the diagnostic equipment to check the ABS system for faults and also they should test ride it and record the work so that if you have any other faults later on, there is an audit trail that may help you if you need help/warranty claims from BMW in future.

+1 on this! At first it sounded as if you're handguards had shifted and that might have been fouling the brake lever preventing it from releasing properly. This is the kind of thing that you should be checking for each time you ride the bike, but BM have issued stickly labels recently to help identify this kind of problem.

Assuming it's not rider error, then there is a fault in the system. You've paid a premium for this bike, it's only got 2 years warranty, get it back to the dealer.

 

[Pukmeister]

As part of the maintenance schedule on my old road car, a Subaru Impreza, a brake caliper clean and rebuild was done. Does anyone know if it's part of the BMW service schedule?

I'll get it booked in to be looked at.

The maintenance schedules state to check pads and disks for wear and fluid levels. They test ride the bike as a final inspection and function check. They change the brake fluid on the 'annual inspection' schedule and conduct a bleed test with diagnostic equipment on the Integral ABS models.

I guess a strip and clean is extra work and would be chargeable over and above the routine service items.

 

[cookie]

it's not part of the schedule.

my dealers, CW, take off the calipers, inspect, clean etc. and charge extra. they tell me it's a necessary precaution.

 

[wilbjr21]

+1 on this! At first it sounded as if you're handguards had shifted and that might have been fouling the brake lever preventing it from releasing properly. This is the kind of thing that you should be checking for each time you ride the bike, but BM have issued stickly labels recently to help identify this kind of problem.

Assuming it's not rider error, then there is a fault in the system. You've paid a premium for this bike, it's only got 2 years warranty, get it back to the dealer.

This is an '08 GSA i.e. hanguards re-designed and do cause the same problems as on previous model years.

This model does not use servos.

I'm with Cookie - can only be a sticking caliper as the brakes share a common line.

 

[thesitetoremember]

I'd agree with the sticking caliper theory if I had not been riding it myself.

Just before accelerating from 30 - 60mph I'd been coasting through a village in 5th gear at 30mph. There was no drag on the brakes going through the village and the brakes were not touched before accellerating.

I know it sounds daft...

 

[Paul90]

Pehaps the piston / pad is sticking a bit, just enough to cause the pad to drag more than it should.

Slowly the pad / disc heats up, expands, drags a bit more, gets a bit hotter ?

As you go faster, it gets hot quicker.

You stop turn off the ignition, things start to cool off and seems to free up.

 

[LiquidLAN]

I'd agree with the sticking caliper theory if I had not been riding it myself.

Just before accelerating from 30 - 60mph I'd been coasting through a village in 5th gear at 30mph. There was no drag on the brakes going through the village and the brakes were not touched before accellerating.

I know it sounds daft...

Bottom line, its an 08 bike that is under warranty... get it back to a dealer and let them look at it. Anything you do is likely to be a reason to invalidate the warranty.

safety bet all round.

 

[tw99]

I will be phoning the dealer tomorrow AM but would like to know if anyone has experienced anything similar.

for info I've checked obvious things like front brake lever fouling etc but nothing to suggest I'm inadvertantly applying brakes.

Your comments please...

I had exactly the same happen on my old 1150 (servo ABS brakes). Binding on while riding, but freeing immediately when you stopped, and restarted the engine. Just needed the caliper cleaning up in my case.

 

[Dicko]

I had similar on my old 1100 when the calipers needed cleaning.

On mine, the brake started dragging and as it got hotter, it got worse to the point where I stopped and couldn't move the bike.

Allowing everything to cool freed it off enough to get home.

R.

 

[Pukmeister]

Be sure to ask the dealers to check the disk(s) for warping through overheating. Its a strong possibility after such a thing happening, which could lead to brake judder etc. They are sure to test ride the bike after they finish working on it, but may not detect judder on a quick test ride, but it will be the bane of your life if you have it.

 

[D6]

silly maybe, but is the master cyl too full?, seen it before, the fact its a twin disc doesnt point to this though

 

[wilbjr21]

Be sure to ask the dealers to check the disk(s) for warping through overheating. Its a strong possibility after such a thing happening, which could lead to brake judder etc. They are sure to test ride the bike after they finish working on it, but may not detect judder on a quick test ride, but it will be the bane of your life if you have it.

Now that is good advice.

 

[igsy]

There is another post on here i have read recently where the guy has 08 GSA and the fault was down to a washer on disc breaking down, all fixed under warranty.