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Sep 4th 2018, 09:09 PM   #1
 
  Mar 2018
  Gig Harbor

  2008 BMW R1200GS Adventure
Anyone Up?! Front Brake Calipers are Binding. R1200GSA.

Bit of an emergency as I need my bike to get to work in 6 hours.

I've posted this on ADVRiders, but they haven't pin-pointed the issue yet either. It's generally a typical brake set up (double disc).

Had to ride to/from work today (this started halfway TO work this morning) applying no front brake because once I press the front brake, it takes a couple minutes for the front calipers to allow the front tire to move again. That is to say: this is dangerous AF!

For the sake of time, please see my post on Advrider.

https://advrider.com/index.php?threa...#post-35856758

And yes... "haha" I initially wrote that post on the Ferry at 0600 this morning and thought the bleeding port on the caliper was a grease fitting... Don't ask me how I jumped to that conclusion (that makes zero sense). It was early... I was freaking out about my breaks... give me a break! Or don't... just help!
Sep 4th 2018, 09:57 PM   #2
 Pavement Tested's Avatar
 
  Jan 2016
  Bremerton

  '12 ZG1400, '08 GSX1300R, '06 GSX-R 750
What brake work was done prior to this happening?

Have you done a good flush and bleed of the system?

What was the state of your pad life when this occurred?

What the fluid level when this occurred? (i.e. over full or too low?)

When is the last time you cleaned the calipers or serviced the brakes?

Do you have ABS? Does the lever get really stiff when this happens?
Are there fuses for the ABS and have you tried pulling them? (I had and ABS Triumph that was activating the ABS on it's own. Pulled the fuses and the issue went away, but no ABS.)


I'll watch for responses.


FWIW: Always clean your caliper pistons before pressing them back into the caliper. DO NOT use brake cleaner on them either! I use Suzuki Performance Motorcycle Wash cut 50/50 with water to clean brakes but any non-corrosive cleaner that cuts grease and grime should work as well. Use a nylon bristle toothbrush to scrub. Rinse with water. Push pistons back in to calipers.

Basic procedure for cleaning would be: remove 1 caliper with pads in it, compress pads together using the lever being careful to keep the pads centered in the caliper(this exposes the "dirt line" on the pistons), remove the pads, clean calipers thoroughly, compress pistons carefully as to not push the others out, install pads, install caliper. Repeat on other side.

Edited by Pavement Tested on Sep 4th 2018 at 10:12 PM
Sep 4th 2018, 10:27 PM   #3
 
  Mar 2018
  Gig Harbor

  2008 BMW R1200GS Adventure
Quote:
Originally Posted by Pavement Tested
What brake work was done prior to this happening?

Have you done a good flush and bleed of the system?

What was the state of your pad life when this occurred?

What the fluid level when this occurred? (i.e. over full or too low?)

When is the last time you cleaned the calipers or serviced the brakes?

Do you have ABS? Does the lever get really stiff when this happens?
Are there fuses for the ABS and have you tried pulling them? (I had and ABS Triumph that was activating the ABS on it's own. Pulled the fuses and the issue went away, but no ABS.)


I'll watch for responses.


FWIW: Always clean your caliper pistons before pressing them back into the caliper. DO NOT use brake cleaner on them either! I use Suzuki Performance Motorcycle Wash cut 50/50 with water to clean brakes but any non-corrosive cleaner that cuts grease and grime should work as well. Use a nylon bristle toothbrush to scrub. Rinse with water. Push pistons back in to calipers.

Basic procedure for cleaning would be: remove 1 caliper with pads in it, compress pads together using the lever being careful to keep the pads centered in the caliper(this exposes the "dirt line" on the pistons), remove the pads, clean calipers thoroughly, compress pistons carefully as to not push the others out, install pads, install caliper. Repeat on other side.
Pretty sure I jacked up the caliper shown in the image in that link (yay rebuild time), but the root cause is still unknown.

To your questions:

What brake work was done prior to this happening?
None that I am aware. I bought the bike in May with 15k miles. It's currently just under 21k.

Have you done a good flush and bleed of the system?
No. I know the bike had the true BMW 600 & 6k mile services done, but he only had records of an oil change and new tires at 12k miles. I changed the oil, the spark plugs, adjusted the valves, and tensioned the spokes at 16k miles.

What was the state of your pad life when this occurred?
~20-30% remaining.

What the fluid level when this occurred? (i.e. over full or too low?)
Nominal.


When is the last time you cleaned the calipers or serviced the brakes?
Never...

Do you have ABS?
Yes.

Does the lever get really stiff when this happens?
This is the first time it's happened, but yes, the lever is very stiff.

Are there fuses for the ABS and have you tried pulling them?
No fuses. All circuits are electronically protected (per the owner's manual). I did attempt to clear any stuck faults in the computer by disconnecting the battery for a few minutes. There were no fault/warning lights displayed, but I've been trying everything I can think of.

I also disabled ABS to see if that changed anything, but it was the same with or without ABS engaged.
Sep 4th 2018, 11:07 PM   #4
 Pavement Tested's Avatar
 
  Jan 2016
  Bremerton

  '12 ZG1400, '08 GSX1300R, '06 GSX-R 750
What does "Normal" mean for the fluid? Do you mean within the high and low marks on the reservoir?

Is the brake lever the factory installed part? I have seen aftermarket levers of lower quality cause dragging and sticking issues due to poor milling resulting in leaving the master cylinder slightly depressed. I feel like this isn't your case since you didn't mention it and it popped up all of a sudden.

If your pads are 20-30% they should be replaced. Your pistons may be extended too far and by the sound of it, one may be sticking. If one is sticking it can cause uneven pressure on the pads and they may be getting slightly cocked which could explain the dragging and sticking.

Are the calipers on slides? Like the rear? I know BMW GS bikes with one front disc have calipers that are on slides. If they are, the slides could be gunked up and not moving smoothly or the caliper itself may be twisting due to a stuck piston.

I'd try giving everything a really good cleaning and attempt to free up all the pistons. For really stubborn pistons I'll use a pair of channel lock pliers with some rags under the teeth to prevent marring. Try to press them all back into the caliper. You'll need to work them a little at a time and watch the reservoir so it doesn't over flow. If you can get things moving and pressed back in, reinstall the pads and then the calipers and work the pads back out on to the rotor with the brake lever. Do one side at a time and for the love of Pete, don't cycle the lever with the pads removed. Not that you would.

One last thing, on some vehicles, turning the ABS off doesn't necessarily turn it OFF off. There could be something funky going on with the electronics that is causing this but I would have to believe that you would get some sort of waning light.
Sep 4th 2018, 11:24 PM   #5
 
  Mar 2018
  Gig Harbor

  2008 BMW R1200GS Adventure
Quote:
Originally Posted by Pavement Tested
What does "Normal" mean for the fluid? Do you mean within the high and low marks on the reservoir?

Is the brake lever the factory installed part? I have seen aftermarket levers of lower quality cause dragging and sticking issues due to poor milling resulting in leaving the master cylinder slightly depressed. I feel like this isn't your case since you didn't mention it and it popped up all of a sudden.

If your pads are 20-30% they should be replaced. Your pistons may be extended too far and by the sound of it, one may be sticking. If one is sticking it can cause uneven pressure on the pads and they may be getting slightly cocked which could explain the dragging and sticking.

Are the calipers on slides? Like the rear? I know BMW GS bikes with one front disc have calipers that are on slides. If they are, the slides could be gunked up and not moving smoothly or the caliper itself may be twisting due to a stuck piston.

I'd try giving everything a really good cleaning and attempt to free up all the pistons. For really stubborn pistons I'll use a pair of channel lock pliers with some rags under the teeth to prevent marring. Try to press them all back into the caliper. You'll need to work them a little at a time and watch the reservoir so it doesn't over flow. If you can get things moving and pressed back in, reinstall the pads and then the calipers and work the pads back out on to the rotor with the brake lever. Do one side at a time and for the love of Pete, don't cycle the lever with the pads removed. Not that you would.

One last thing, on some vehicles, turning the ABS off doesn't necessarily turn it OFF off. There could be something funky going on with the electronics that is causing this but I would have to believe that you would get some sort of waning light.
Just HYPOTHETICALLY... what would happen if I cycled the lever without the pads in?
Sep 5th 2018, 01:20 AM   #6
 Pavement Tested's Avatar
 
  Jan 2016
  Bremerton

  '12 ZG1400, '08 GSX1300R, '06 GSX-R 750
Quote:
Originally Posted by Didley
Just HYPOTHETICALLY... what would happen if I cycled the lever without the pads in?
Doing it too much could push a piston all the way out passed (past?) a seal.

Sorry for the delay. Fell asleep.
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Sep 5th 2018, 04:50 AM   #7
 
  Mar 2018
  Gig Harbor

  2008 BMW R1200GS Adventure
Quote:
Originally Posted by Pavement Tested
Doing it too much could push a piston all the way out passed (past?) a seal.

Sorry for the delay. Fell asleep.
Haha. It's all right. I tried for the longest time to leave the calipers connected, but finally removed the brake lines and pulled them all the way off. Should have done it sooner though because I ended up damaging the bearing surface of one of the pistons.

Question: Where can I find just the pistons for the caliper? Like today.

After I removed the brake line on the left caliper and (eventually) reinstalled it, the brakes stopped binding on both sides. The front brakes are complete mush, though, so I need to bleed them and decided I'll go ahead and do a flush while I'm at it.

But I'm afraid that once I do all this and go through all the trouble of flushing the lines, that the issue will return when there is sufficient volume in the system to increase the pressure.

We'll see, I guess. This has been a learning experience for sure. I knew I needed to look at the brakes, but got complacent with the bike since it's been running so well.

It should have occurred to me that the previous owner only put 15000 miles on it in TEN years (it's a 2008). The fluid brake fluid is a murky, yellow snot color and opacity. I think that is purely due to age and not contamination, but I still don't know what caused the calipers to seize. We'll see what happens after the flush!

Once I dug into it and messed up a piston, it all turned out to be really simple.
Sep 5th 2018, 06:19 AM   #8
 curve addict's Avatar
 
  Apr 2016
  Des Moines, WA

  ...1987 Yamaha FZR1000...
In my years of working on bikes, and those four-wheeled things, I've learned this:

In a bike (or car) that's been running, the most common cause of brake lock up is a clogged equalizer port in the master cylinder. There are two holes in the bottom of the master cylinder reservoir. If your bike has remote reservoirs, these holes are under that plastic elbow.

When the brake lever is fully released, the tiny port opens to allow the fluid pressure from the calipers to return to atmospheric. This creates slack, so to speak.

If you can only see one port, or the fluid is too dirty to look through, then this port is clogged. As the fluid in the calipers heat up, the calipers close and eventually clamp down on the rotor.

The ideal fix is a disassembly and thorough cleaning and rebuilding, or replacing, the unit. A quick fix is to gently work a very fine wire into that port and push the sediment plug through. Then get home and fix it correctly.

A roadside remedy is to crack one of the caliper bleed bolts to release the brake. Stay off the brake or it may lock again and get to a safe spot to effect a repair.

Note: This symptom can also be caused by a master cylinder piston that is not fully retracting as it should.
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Sep 5th 2018, 09:43 AM   #9
 Pavement Tested's Avatar
 
  Jan 2016
  Bremerton

  '12 ZG1400, '08 GSX1300R, '06 GSX-R 750
Brake fluid should be flushed every 2 years. New fluid is usually clear to a light yellow tint depending on brand.

A new piston will have to be ordered from BMW or another parts house. Order a master cylinder rebuild kit too. If you're replacing one piston, you should probably replace all of them.

BMW P/N 34112338257 is a rebuild kit for your caliper. It looks like it includes new pistons and software (O-rings and shit) for 1 caliper.

Google the P/N and it will give you a variety of places to order from including eBay, Amazon etc.

A real cursory look into a master rebuild kit didn't yield much. I'd need to know the P/N for your master to get closer. The BMW shop should be able to point you in the right direction.

You may be able to get away with doing a minimal tear down of the master ad cleaning it out real well.

There's this option too: https://www.ebay.com/itm/2007-BMW-K1...1aa6k1&vxp=mtr Looks cheaper than buying the caliper rebuild kit.
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Sep 5th 2018, 10:17 AM   #10
 mars's Avatar
 
  Jan 2016
  McMinnville, OR

  CB160RR, CB550, SportClassic
Quote:
Originally Posted by curve addict
...the most common cause of brake lock up is a clogged equalizer port in the master cylinder....A quick fix is to gently work a very fine wire into that port and push the sediment plug through. This symptom can also be caused by a master cylinder piston that is not fully retracting as it should.
I've been having this issue as well and my mechanic friend explained that he used to see this all the time at the shop, noting that oftentimes when that return port would clear (using the wire method), brake fluid would squirt everywhere due to the built up pressure, so take precautions.

Also, FWIW, according to the internets, another cause of this sort of thing can be aging brake lines. Apparently, the plastic ones sometimes start to come apart in strips that act like a check valve inside the hose, allowing fluid to pass in one direction but not the other.

In my case, cleaning everything and jamming a piece of safety wire in and out of the return port in the master cylinder didn't help immediately, but it did eventually free up on a subsequent ride. However, without a rebuild kit for my master cylinder (I can't seem to find one anywhere), it's probably only a matter of time before it clogs again or fails altogether, so I'll be replacing it. Word is, the Brembo radial master cylinders that come stock on R6s of recent years are a fantastic upgrade for most bikes, though I'm not sure about compatibility with your ABS.

Edited by mars on Sep 5th 2018 at 10:22 AM Reason: phrasing
Sep 5th 2018, 11:07 AM   #11
 Pavement Tested's Avatar
 
  Jan 2016
  Bremerton

  '12 ZG1400, '08 GSX1300R, '06 GSX-R 750
Quote:
Originally Posted by mars
...another cause of this sort of thing can be aging brake lines...
I'd have to double check the periodicity but most manufacturers recommend replacing all the rubber bits (i.e. brake lines, coolant hoses, fuel lines etc.) every 5 or so years. They wear out, get structurally compromised by the fluids in them and dry rot from the elements.
Sep 5th 2018, 12:55 PM   #12
 
  Mar 2018
  Gig Harbor

  2008 BMW R1200GS Adventure
Quote:
Originally Posted by Pavement Tested
Brake fluid should be flushed every 2 years. New fluid is usually clear to a light yellow tint depending on brand.

A new piston will have to be ordered from BMW or another parts house. Order a master cylinder rebuild kit too. If you're replacing one piston, you should probably replace all of them.

BMW P/N 34112338257 is a rebuild kit for your caliper. It looks like it includes new pistons and software (O-rings and shit) for 1 caliper.

Google the P/N and it will give you a variety of places to order from including eBay, Amazon etc.

A real cursory look into a master rebuild kit didn't yield much. I'd need to know the P/N for your master to get closer. The BMW shop should be able to point you in the right direction.

You may be able to get away with doing a minimal tear down of the master ad cleaning it out real well.

There's this option too: https://www.ebay.com/itm/2007-BMW-K1...1aa6k1&vxp=mtr Looks cheaper than buying the caliper rebuild kit.
That POS eBay seller took out the pistons, but doesn't actually say it. He just says "The package you receive will contain only what is in the pictures nothing more and nothing less..."

There's one picture where if you are looking closely enough, you should be able to see the edge of the pistons. Asshole left the old brake pads in to cover it up.
Sep 5th 2018, 01:10 PM   #13
 Pavement Tested's Avatar
 
  Jan 2016
  Bremerton

  '12 ZG1400, '08 GSX1300R, '06 GSX-R 750
Quote:
Originally Posted by Didley
That POS eBay seller took out the pistons, but doesn't actually say it. He just says "The package you receive will contain only what is in the pictures nothing more and nothing less..."

There's one picture where if you are looking closely enough, you should be able to see the edge of the pistons. Asshole left the old brake pads in to cover it up.
Hmm... I didn't look that closely at the pics. Are you absolutely sure they haven't been pushed all the way in the calipers? It seems like a waste of time to remove the pistons and put the pads back in.

Part out guys will invest as little time as possible into taking things apart. Time is money and they don't like to waste either.
Sep 5th 2018, 01:57 PM   #14
 
  Mar 2018
  Gig Harbor

  2008 BMW R1200GS Adventure
Quote:
Originally Posted by Pavement Tested
Hmm... I didn't look that closely at the pics. Are you absolutely sure they haven't been pushed all the way in the calipers? It seems like a waste of time to remove the pistons and put the pads back in.

Part out guys will invest as little time as possible into taking things apart. Time is money and they don't like to waste either.
Yeah. The way he phrased "nothing more... nothing less" clued me into the fact that he's not just coming out and saying something.

Punks, man... I tell ya. I attached the image here. No other reason to put the old, shitty pads back into the caliper other than to hide the holes where the pistons should be.
Attached Thumbnails
Anyone Up?! Front Brake Calipers are Binding. R1200GSA.-s-l1600.jpg  
Sep 5th 2018, 07:25 PM   #15
 MarvTravis's Avatar
 
  Jan 2016
  Kirkland, WA

  Kawasaki ZX-14
If the caliper pistons aren't damaged, you can rebuild the calipers, after acquiring only replacement seals. Here's a pair of excellent Delboy's Garage videos detailing how to do a complete caliper build, including polishing the pistons:



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Edited by MarvTravis on Sep 5th 2018 at 08:35 PM
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