Dragging brake caliper

[cofz1]

After much debate, I picked up an 06 FJR. Only got to do a real short & slow test ride. Seemed fine. Bike started pulling left on the ride home.

Figured out with xc1974 that the left rotor was dragging and pulling the bike left. How you ask? Take a screwdriver and open up the pads on that side and the bike rides straight. Pump up the lever, bike pulls left, and rotor gets REALLY HOT! (right side and rear completely cool)

Bought a used caliper on fleabay from a '10 model. Figured it would be OK, it's not new, but it's four years newer than the one on my bike. Caliper shows up, looks like it has quite a bit of brake dust buildup. Thinking to myself, this might be a bad sign. Sure enough. Installed the "new" one, bled the line. THIS ONE DRAGS TOO!!

I've never seen this problem with these bikes or any other bike. Has this happened to others? Am I missing something? Does it have anything to do with the linked brakes?

 

[C&C]

What you describe leads me to believe you have a brake line problem. A deteriorated brake line can act like a one way valve (allowing pressure to the caliper but not releasing fluid pressure back to the resevoir). This is fairly wide known to happen in automobiles, so I would think, just as possible in our bikes.

 

[RaYzerman19]

Could be the brake line, could be the caliper pistons sticking. Why not remove both, clean and rebuild with new seals. Well, first, check that the pistons are moving freely. If you can't push the pistons back in, loosen the bleeder screw. If they then go back in easily, it's the line. If they're still stiff, time for new seals.

 

[olsonm3915]

It's not the caliper pistons sticking, since it happened with two different calipers.

I've heard many times about the possibility of a brake hose acting as a one-way valve but I seriously doubt this is the cause, it seems to be an urban legend more than a factual occurrence.

I had the exact same thing (sticking caliper resulting in an overheated front disk) happen on a 1200 Gold Wing as I was riding it home after buying it. It was a blocked return port in the master cylinder. The previous owner had not changed the brake fluid in a long time, and some fluid crystallized into a hard lump, which blocked the return port. The fix was to flush out the old fluid and poke a fine soft copper wire through the hole in the M/C.

 

[joebiodiesel]

If it's a brake hose, it is easy to diagnose. Just spin the wheel by hand to verify that the caliper is still dragging, then open the bleeder on that caliper to relieve any pressure. If the wheel now spins freely, then it is a brake hose, or master cylinder that is causing the dragging. If it still drags, then it's still a stuck caliper.

If you have a second caliper that is sticking, I recommend you take it apart, run some emery cloth around the piston and bore, clean it thoroughly, and reassemble it. I've done a bunch of them on bikes/ATVs with no trouble.

Joe

 

[wfooshee]

A dragging brake cannot steer the bike, y'all.

I'm sure you've seen those "primitive" motorcycles with a single disc rather than one on each side? Are you telling me that they're gonna crash and burn every time they jump on the front brake??!!!??!?!?

Also, if it actually steers under braking you have another issue. It may be that the steering effect goes away when you free up the dragging brake, and comes back when you use the brakes. I will personally guaran-damn-tee you that if the caliper weren't sticking, this bike would steer on the front brake. Something's not lined up in the front end.

That said, if the caliper is not releasing and dragging the pads, you need new seals. That's all. BTDT.

Ruling out the calipers because you replaced a suspect one with an unknown used one is not good troubleshooting, either. You don't know, do you, that the "new" caliper is good? You said it was crudded up and needed cleaning, and those are the ones with suspect piston seals.

 

[cofz1]

I posted up about a front brake caliper dragging a while back. After more time and money spent I'm still chasing this thing I called a dealer today, they told me I pretty much covered all the normal stuff. They also said they've never heard of this before. They said the next step was to bring it in. Check out what I've done so far and tell me if I missed anything thing.

This is a 2006A

Problem: Left front brake caliper drags. Seems like the two outside pistons dragging. When I pull the pins the inner pads fall down. I have to pull back on the outer pads to get the piston back so the pad will slide out.

So far:

Took off master cylinder, cleaned, reassembled.

Had rotor checked for warpage, none. It's discolored from getting hot, but still straight.

Flushed fluid, replaced.

Put new pins in that hold the pads. (not the anti-rattle clips)

Put in new pads.

Bought seal kit and disassembled, cleaned, and rebuilt caliper.

Results: With the front wheel off the ground I can spin the wheel a little over one turn. My brother has an '08 and it will spin 3-3 1/2 turns using the same method.

What am I missing? What's next?

 

[FJRay]

I would open the bleeder without touching anything else to relieve any pressure. If the wheel turns freely at that point then something is holding pressure in the line. Sometimes the rubber hoses can cause issues but it's rare and if it only causes one caliper to drag it's not the master.

If opening the bleeder doesn't relieve the draging I would hit the caliper with a rubber hammer. If that lets it spin free then something in the caliper is hanging up and you need to recheck your work to see if some thing is binding a piston. It doesn't take much to cause problems. Good luck.

 

[Niehart]

PM sent.

 

[wfooshee]

In your original post you said that the bike pulls left on braking. Does it still do that?

If so, that is NOT a brake problem!!!!!!! It's a frame or fork alignment problem, telling you that the bike is bent somewhere. The ONLY way the bike can steer by loading up the front end is if the front end isn't centered on the bike.

I repeat my assertion that the bike will not steer towards a stuck brake caliper. If that kind of "physics" were to happen, then every bike out there with a single front disc would crash every time they used the front brake.

On your used caliper, did it come with the pistons, or did you have to re-use the ones you had? If so, why assume the pistons are OK? If you've got one that's not round, and not pointed straight out of the cylinder, then that'll be an issue.

FJRay's check of relieving pressure with the bleed screw is a good test. If that backs the pads off then there's a hydraulic issue. If it doesn't then you have a mechanical bind in the caliper somewhere.

I think you've got two issues. Something is binding your brake, and your bike is bent somewhere. Separate problems.

 

[cofz1]

Tried the brake bleeder check last night. After loosening it up and spinning the wheel I got a little more than two turns out of it. Now the plan is to trace my way up the line until I find something.

Thanks for the help everybody.

wfooshee- Here's my experience, maybe I missed something.

I slabbed it across Iowa, Nebraska, and Colorado with this problem. At every gas stop I got out a screwdriver and pushed the pads away from the rotor and it rode fine. (admitted safety issue) When I went through Des Moines and Omaha I had to use the front brake. After I used it the problem came back.

I know it sounds like I'm making this up. I ride and race supermoto, so I understand bikes with only one rotor. My experience points to the two being related. I appreciate your help. It's entirely possible that I have two separate issues going on.

Right now I'm only trying to fix the problem that I can reproduce in my garage.

 

[wfooshee]

Well, once the brake problem gets fixed and the caliper releases properly, you're still going to have the issue of the bike pulling left while using the front brake.

It's not pulling to the left because the left caliper sticks, it's pulling to the left because the brakes are on. It would do the same if the right-side caliper was sticky, because whatever's not straight is pulling the bike that way when the front wheel has drag, whether intentionally dragging (brakes on) or not (brakes stuck.)

It would involve some bleeding, and I don't know the hose routing on ABS bikes, but I'm wondering if it's possible to swap hoses on the front calipers and see if the sticking problem follows the swap.

I don't know if both front hoses come all the way from the ABS unit or if there's a fitting that splits left and right from a single feed hose from the ABS. If they go all the way back you may actually have an ABS unit problem. Swapping the hoses at the calipers would still be meaningful either way. It would definitely tell you if it's a hydraulic issue or a caliper issue.

 

[ahchiu]

Check your steering head and wheel bearings.

 

[cofz1]

Good idea. I think there's enough length to swap the front hoses and find out.

Checked steering and wheel bearings. Seem normal.

 

[ahchiu]

Good idea. I think there's enough length to swap the front hoses and find out.

Checked steering and wheel bearings. Seem normal.

How did you check the steering head? have you checked the torque on the steering head? if there is any slop in the head when you brake the steering head may move slighty and your alignment may be off and have your wheel off center and may be causing the front to pull to the side. as others have said braking on one disk will not cause your front to pull to the side.

 

[dcarver]

I'm not sure I agree with Walt but I don't know why.. :huh:

Will have to think on this some more.

For every action, a reaction?

Old BMW /2's torque to the right when given throttle (no counter balancer)

Dozers turn when a track clutch is disengaged (inverse of a braking/friction)

Do I recall my Z1 Kawi and CB750 twitching with but one single disc?

Or was that caused by other effects?

Interesting question..

hmmm

 

[wfooshee]

Addressing the issue of "unbalanced" braking (or motive) force:

The braking force is not applied to the bike from beside the wheel. It's applied to the bike from the contact patch of the tire. That should be exactly in front of the bike itself, and centered. If it's centered, the bike stays straight. If it's not, it will try to steer the bike.

This is not the same thing as a car losing the brake on one side and not the other. That's 2 separate brake points, and if unbalanced, the car pulls to the stronger brake. That "2 separate points" applies top the dozer example, too.

Braking (or power) is applied to the vehicle at the road surface, not at the brake itself. The brake slows the wheel, the wheel slows the bike.

Is the drive shaft centered on the hub? No, it's hanging out there on the left side of the wheel. Well, then, why don't the bike turn when you give it gas, when only one side of the wheel is being driven? Because the bike is being driven at the road surface under the tire, which is in the centerline of the bike. No unbalanced force, no steering.

 

[dcarver]

Hmmm..

Imagine a case where the disc was 4 feet to the left of the tire.

Would not the force of braking on that disc cause deflection to the left front fork tube and thus direction?

Sure, the contact patches are in line, but energy is applied to left fork assembly, not right, causing an imbalance?

Or, put another way, if the left fork tube hits an immovable object (tree, rock, etc) would not the mass rotate around the deceleration causing course change?

(Please bear with me, I have a hard time understanding this physics stuff, but I love to ponder and bear total humility to facts!)

 

[900gc]

Does it act the same after you move the pads back and apply ONLY the rear brake to only activate the linked pad in the front caliper? Depending on the result, it may narrow down the issue to a specific piston. Maybe you can swap the rotors around just to see if that makes any difference as well. Lots of good advice in this thread so far to do/check. I'm assuming your bike was not crashed and rebuilt perhaps causing alignment issues with multiple components?