2006 R1200RT Front Brake Dragging Excessively

Well, I searched as best I could, but did not find anything. I know some dragging of the brakes on the rotors is normal, but my bike has this to a problematic degree where I notice a waver in my front wheel when starting in first gear and it's very difficult to push the bike. It does appear to be wearing my rotors excessively as well. We're talking it's difficult to spin the front wheel at all, and it basically moves as far as you push it then stops.

Both calipers seem to be acting fine. The pistons move freely and push back as normal. When the calipers are off, the wheel spins freely and appears as it should be.

Once the calipers are remounted, the wheel continues to spin with very minimal drag. Once the bike starts up and the brakes are applied, the drag resumes and the.

The brakes were just bled by Ted's BeemerShop and they said everything appeared to be in spec and working normal. There was one old fault code for an overpressure in the ABS system that we haven't been able to reproduce.

Any ideas?

Unfortunately, I just bought this bike and this problem was not disclosed to me at the time so I don't have any details on the bike's history.

Several thoughts on your situation:

1. Has the bike lived in a hot part of the country? Desert etc.?

2. Has the bike lived on or near the ocean?

either of the above might contribute to hardening of the rubber parts inside the caliper which are supposed to "spring back" retracting the pucks a bit when the brakes are released.

3. Does the hand brake return all the way back to the "off" position?

4. Is the master cylinder (on the handle bar) too full?

The bike spent its life in Sacramento, which is general a dry climate with some pretty hot summers.

The pads seem to spring back just fine when the bike is off. It only clamps down once the bike has turned on the and the ABS system has kicked in. The pistons seem to move so freely I doubt there's anything holding them up from going back. From my understanding, when the lever is released the the fluid pressure drops, that drop in pressure should be pulling the pads back on its own.

The brakes seem to work fine at normal riding speeds. The drag become noticeable during low speed maneuvering, however. The brake lever returns to normal and the master cylinder is at the correct level (and the entire system was just bled by the pros).

Thanks for the good ideas though. I figure I may end up rebuilding both front calipers as part of my attempt to fix this problem, though if I can find the solution without doing it, I'd be quite happy.

Check for corrosion in the master cylinder.
Piston may be hanging up and not fully releasing.
Brake fluid is (help me here, Mr. Science . . . . hygroscopic!) well it attracts moisture.
Sounds similar to my 2007 RT symptoms and that's what we found.

I will put the master cylinder on the things to check.

I pulled the calipers off today and the pistons push back very easily. After pushing them back and re-attaching, the wheel spins freely. Once I pump them back up (even with the bike off) it slowly starts to grab until the front wheel only moves exactly as much as I push it.

I can on ly think of 2 things.

Master cylinder not returning fully.

BRAKE HOSE.

David


If you have the front brake hanging up, then crack (open then close) a bleeder with out touching anything else does the problem go away?

Well, finally had time to strip down the bike and take a look at it. So far, here are some things I have tried.

- I opened up the control circuit bleeder while the front brake was dragging (no pressure on the brake lever though) and no fluid came out and there was no release of the dragging upon opening the bleeder.

- I did the same with the caliper bleeders and had no release of pressure and/or the dragging.

This leads me to believe it's not a pressure issue or an issue of the master cylinder not returning. I believe if that was the case, then releasing the pressure in the circuit should have relieved the brake dragging and allowed the wheel to spin more freely.

My only remaining guess is that it's a problem at the caliper level. Which means tomorrow I'll be taking the front caliper's off, opening them up and cleaning/lubing them. I'm not sure if there's a rebuild kit out there for them or how I should go about it.

This is my first time removing the gas tank and all the jazz from my bike and boy was it a bit of work. I took the opportunity to install the white front turn signals that I just got.

Anyways, I'm still open to any other ideas. Otherwise I'm banking on it being a caliper issue.

Seals do indeed provide the initial retracting force and if stiff or worn may not function.

If you're going to the trouble to take the calipers apart and clean, you should put in new seals- its pretty easy if you have them. Check the parts lists for availability.

Some amout of residual drag is normal. It is brought to its minimum value by rotor knockback after the seal-initiated piston retraction.

I'm having trouble looking up a rebuild kit for my bike. The only thing that looks like it is called the "REPAIR SET BRAKE CALIPER" and costs $83, which seems a bit steep for a few pieces of rubber. Also on some sites it says this is not for integral ABS bikes.

http://www.2wheelpros.com/oem-parts/bmw-set-repair-brake-caliper-d-32-36mm-34112338257-part.html

I think its reasonable since it comes with pistons.

David

Well, problem is solved. After inspecting the brake pads a little closer, I noticed the metal heat plate on the back appeared warped and had a layer of silicon-like rubber on it that seemed to be gunked up and pilling on the back of the pads and the pistons. Removed the warped heat plates and cleaned it all up and it's no longer dragging.

Of course it had to be something so simple. This is a temporary fix until I can order some fresh brake pads and change them out just for good measure. Thanks for all the help!