1150GS Binding Front Brake

John Leah

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Hi,

I have a 2002 1150GS ABS with 19,000 miles on it. The PO rarely used it hence the low mileage but, in the less than two years that I've had it I've put on about 6,000 miles including a 2,000+ mile tour of Scotland this summer. I do occasionally ride in rain but use other bikes when the roads have been salted.

It's been reliable but recently the front brake started binding and soon became hard to turn by hand. So, this afternoon I removed the callipers (one at a time) to clean them and found all pads worn nearly to the metal (oops!). I pumped out each piston in turn (but not so far as to remove them) and using plenty of brake cleaner and an old toothbrush got them all shiny like new. I cleaned the old pads (new ones on order) and refitted them with Copaslip on the pins but, alas, they still bind.

It's getting dark now and, as I work outside, have had to stop for the day but I'm not sure what to do next. I should have checked each side in turn but didn’t – besides, isolating the problem to a side still wouldn’t have helped me cure it.

Were it one of my other bikes I'd have no hesitation in stripping the callipers, replace the seals (and maybe pistons) and change the brake fluid. But, it has ABS which is scaring me off as all of my manuals seem really, REALLY keen that I take it to my local dealer. So keen, in fact, that they don't even tell me how to.

So, what could be causing my brakes to bind? If it’s something simple like seals it would pain me to have to take it to my nearest dealer (70 mile round-trip) just because I couldn’t change the fluid.

Even if I can resolve the binding brakes without disturbing the fluid it does still need changing so is this something I can do myself? Maybe with a vacuum brake bleeder?

Cheers,
John
In sunny Devon
 
The early non servo ABS which I think your bike should have is easy enough to bleed, especially with a vacum bleeder or some plastic syringes, there are a couple more bleed points under the tank if you get a lot of air in there, when mine had a binding brake it was corrosion behind the piston seal, the calipers are pretty conventional and should hold few surprises if you have done the job before.

Stewart
 
Hi Stewart,

Thanks for the reply.

I have just come across a GS manual pdf and it gives bleeding instruction and you’re right there is the bleed point hidden beneath the tank.

OK, now I know how to change the fluid I will as it needs to be done but I must still resolve the binding.

Corrosion behind the seal sounds feasible so I’ll strip them down and clean them but was it the callipers or the pistons that were corroded and, if the pistons, did they need replacing?

I just want to try and get the bits I need before I start and as I’ll fit new seals would like to order pistons too if I need them.

Cheers,
John
 
The overhaul kits seem to invariably include new pistons, which pushes the price up, if you have done similar stuff before, you might be lucky, I have only had a very few that leaked after a strip, clean and rebuild, even using all the original bits, okay for your own bike if you trust your skills, if its a client then you need to cover yer eras
 
Binding

Last time this happened to me it turned out to be a collapsed brake line. While it appeared to be OK on the outside the inner tube had collapsed in effect squeezing the fluid and pushing the brake pads. Changed the tube and hey presto.
 
Hi guys, thanks for the replies.

Stewart: Yes, it is my bike so it’s me that pays the price of cocking it up.:)

That said, over the years I have worked on many a hydraulic braking system replacing seals, pistons and hoses and am still here to tell the tale – it’s just that I have no experience of ABS systems and was unnerved by the manuals warnings to keep off but then they would, wouldn’t they? Haynes don’t want to run the risk of litigation and BMW, via the bike’s handbooks, seek to encourage business for their dealer network. The pdf factory manual I found gives a good explanation of the order of things so I’ll be alright (provided I can lift the tank off). Besides, my ‘local’ dealer is 35 miles away which is a bit too far to ride without brakes so I’ll have to do the job. I have another bike to use while the GS is out of action so can take my time.

Marcopol: Thanks for the tip about collapsed hoses. It reminded me of something I’d heard long ago but had forgotten that they can act like a one-way valve so I will replace them too.

I think MotorWorks and I are going to become very good friends.:)

Cheers,
John
 
it could be corossion on the caliper itself, causing the pads to stick?

That's what I was banking on but a good cleaning yesterday didn't fix it. The pads were a bit on the thin side with much corrosion on the ends (which I cleaned off) so I'll try the new ones when they arrive before stripping it too much. I still think I'll fit braided hoses and change the fluid though even if the new pads are the answer.

Cheers,
John
 
Originally Posted by ELIMINATOR
it could be corossion on the caliper itself, causing the pads to stick?



That was my thinking. Do the pads slip easily into the caliper or do they bind on the caliper body?

I once suffered a locked front brake on my 2003 Evo braked model and as this followed hard on the heals of a friend having to take his in for a new ABS unit with the same problem I was expecting the worse (luckily it was sill in warrenty). I got the bike home and soon realised that the pad was tight in the caliper body with a build-up of dust & crap, a quick clean and it was all working ok.
Kept the calipers clean with regular cleaning ever since.
 
Certainly the old pads were pretty scabby and, while I did clean them, perhaps knowing they needed replacing maybe I wasn’t as thorough as I could have been.

MotorWorks have now sent the new pads which I was hoping to fit today but it was too wet (I work on the lawn so not ideal). Provided it’s dry for an hour over the weekend I’ll fit them and see if that makes a difference. Crossing fingers.

Cheers,
John
 
Remember to copaslip the caliper & pads where they contact. Red rubber grease (a smidge) on the piston caliper interface.
 
Remember to copaslip the caliper & pads where they contact. Red rubber grease (a smidge) on the piston caliper interface.

Good advice, thanks. I always use Copaslip but have only ever used red brake grease when fitting pistons and not when they're already in. Would the seal just wipe it off? Well, it's no harm to use it and I have some around here somewhere.

Anyway, I'd already fitted the new pads and can report it's a whole lot better: before I could barely turn the wheel by hand but now I can spin it but only one full revolution so, while the old pads were sticking, something is still binding a little. When it cools down I'll whip the pads out and smear some brake grease on the pistons.

Cheers,
John
 
I've just had it apart again, red-greased the pistons and rode it around for a couple of miles but it still only spins one revolution. Is that sufficient for an MOT fail?

What the improvement brought by the new pads shows though is that the hoses are OK so the problem is within one or both callipers and I think I've isolated it to one offending piston: I’m fairly sure it’s one of those in the right-hand calliper.

I’ll talk to my MOT tester on Monday and see what they think. If it’s good enough for a pass I’ll stick with what I have over winter as it doesn’t get ridden that much when the roads are plastered with salt and do it properly with a fluid change when it warms up again. Mind you, it’s been pretty warm today; working on the bike, outside, wearing a T-shirt in November sounds good to me. :)

If it isn't good enough for a pass then I'll have to overhaul the callipers and change the fluid.

Thanks for all the advice guys:)

Cheers,
John
 
If the discs haven't turned yellow or blue, you probably have nothing to fret about. New pads on a scored disc tend to genrate heat until bedded in, well, that's my opinion and experinece anyway.
 
MOT tester said it's fine and not dragging anywhere near enough for a fail so I have it booked in for a test on Wednesday.

I don't have any long trips planned until Scotland in May/June so can wait until next year to change the fluid.

Cheers,
John
 
Following the Summer tour I noticed that the front brake losing effectiveness so now with the 15GS back at base I have been investigating.

Every pad at the front had a different thickness with one down to the metal - this comes 2000 miles after an expensive Dealer 24,000 mile service (never again!). There's obviously been stiction with the pads caused by dirt-
Go easy with the copper grease - it seems to attract muck - look at the 4th photo down:
HERE

I've overhauled all the seals and changed the pistons plus new braided brake lines, new pads (obviously). The master cylinder seems to be OK.

The back brake was OK but I stripped out the seals and found one of the "dust" seals distorted.
 


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