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Sticking / dragging front brake

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Hi guys. Sorry if this has already been discussed, but I couldn't find anything that solves my problems.

 

2014 CRF250R with about 45hrs on it. Bought it new.

 

The front brake has recently started "dragging" or sticking on just a little bit. It's not noticeable while riding, but when the front wheel is off the ground and I spin the wheel it stops very quickly. I can hear the brake dragging. I think it's only started doing it since a small crash I had a few weeks ago. Its a 280mm CRF Stuff brake (non-floating rotor, OEM floating calliper).

 

This is what I've got so far:

- No visible damage to calliper or mount

- OEM pads still with plenty of meat

- Tried different wheel with different rotor and pads

- Cleaned all the dirt out of the calliper

- Bled brake

- Cleaned out and re-greased calliper mounting pin thingys

- Removed wheel, re-aligned forks and triple clamps, replaced wheel

- Fluid not overfull i.e. small visible air gap in sight glass on master cylinder

 

I'm running out of ideas. My leading theory at the moment is that the calliper mounting pins are very slightly bent. I took them out to inspect but they didn't look bent so not too sure.

 

Any ideas?? do you think replacing the pins will help?

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Hi guys. Sorry if this has already been discussed, but I couldn't find anything that solves my problems.

 

2014 CRF250R with about 45hrs on it. Bought it new.

 

The front brake has recently started "dragging" or sticking on just a little bit. It's not noticeable while riding, but when the front wheel is off the ground and I spin the wheel it stops very quickly. I can hear the brake dragging. I think it's only started doing it since a small crash I had a few weeks ago. Its a 280mm CRF Stuff brake (non-floating rotor, OEM floating calliper).

 

This is what I've got so far:

- No visible damage to calliper or mount

- OEM pads still with plenty of meat

- Tried different wheel with different rotor and pads

- Cleaned all the dirt out of the calliper

- Bled brake

- Cleaned out and re-greased calliper mounting pin thingys

- Removed wheel, re-aligned forks and triple clamps, replaced wheel

- Fluid not overfull i.e. small visible air gap in sight glass on master cylinder

 

I'm running out of ideas. My leading theory at the moment is that the calliper mounting pins are very slightly bent. I took them out to inspect but they didn't look bent so not too sure.

 

Any ideas?? do you think replacing the pins will help?

 

This was covered here in the last day or 2. Basics, yes you need straight pins, pretty much corrosion free. And a slight amount of drag is not abnormal.

 

Mike

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A quick test is to spin the front tire and make sure it is dragging.  If so, open the bleeder on the caliper, and see if the wheel frees up.  If so, then pressure is being applied to the caliper.  If pressure is being applied to the caliper, then it could be dirt built up behind the master cylinder piston, where it can't return fully to its rest position.  Or possibly a bent lever hold the brakes applied at all times.

 

 

If it still drags after you open the bleeder, then the problem is at the caliper.  A bent pin, caliper, or mounting.  Maybe one of the anti rattle shims is tweaked keeping one of the pad(s) in a bind against the rotor. 

 

If you had your caliper apart and removed the piston oring, you may have it installed incorrectly.  The oring is square cut, but it's cut at an angle.  When the piston is pushed out to press against the pad, it tilts the oring slightly.  When you release the brake lever, the oring that is now tilted, will return to its natural square postion, and slightly pull the piston away from the pad.

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Could you of bent your rotor slightly in the small wreck? That can cause issues like what you are describing even with a very slight bend.

Well I kinda skimmed over the tried a different wheel and rotor part so sorry about that.

Edited by pre-mixed
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Thanks walkingwounded. That's good troubleshooting advice. I'll give it a go this week and see if I can isolate the problem.

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A quick test is to spin the front tire and make sure it is dragging.  If so, open the bleeder on the caliper, and see if the wheel frees up.  If so, then pressure is being applied to the caliper.  If pressure is being applied to the caliper, then it could be dirt built up behind the master cylinder piston, where it can't return fully to its rest position.  Or possibly a bent lever hold the brakes applied at all times.

 

 

If it still drags after you open the bleeder, then the problem is at the caliper.  A bent pin, caliper, or mounting.  Maybe one of the anti rattle shims is tweaked keeping one of the pad(s) in a bind against the rotor. 

 

If you had your caliper apart and removed the piston oring, you may have it installed incorrectly.  The oring is square cut, but it's cut at an angle.  When the piston is pushed out to press against the pad, it tilts the oring slightly.  When you release the brake lever, the oring that is now tilted, will return to its natural square postion, and slightly pull the piston away from the pad.

 

I tried what you said. Opened up the bleeder on the calliper, but it still dragged. So I suppose this means that the calliper is the issue. I haven't pulled the calliper apart so the piston O-rings should be fine. I guess the next step will be to replace the mounting pins.

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As mentioned in an earlier reply, some drag is normal, but what is considered normal/abnormal comes with experience.

 

When you spin the wheel, does it noticeably come to a stop, or casually coast to a stop?

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nah its definitely abnormal. it comes to a very quick stop. I've been riding and working on my own bikes for years, and I know how freely the front wheel should spin. as a comparison, the rear wheel spins a lot easier than the front, which it shouldn't considering the extra drag caused by the chain.

 

I've attached a short clip showing how quickly it stops. in the video version you can hear the brake dragging, but I couldn't upload it.

front_brake.gif

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you didn't mention you have an aftermarket and I'm guessing oversize floating disk.

 

IMO floating disks have no place on dirt bikes.

You might want to spray some WD40 onto the floating pins and make sure they float freely.

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I've never used a floating disc, and it may be that since it floats and is not held in a 'as true circle' as a standard disc, it may drag a little more on the pads.

 

Remove your brake pads, and the caliper should slide easily back and forth on the pins.  If so, it may just be the characteristics of that setup.

 

For safety reasons, I would take it to the track and work the front brakes as usual.  After a bit of riding, throw it up on the stand and see if the drag has increased , or stayed the same. 

 

If it has increased, I would dig deeper, if it has stayed the same, you're probably ok, but definitely keep an eye on it. 

 

A front fender grab over a jump ain't good.  :cripple:

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you didn't mention you have an aftermarket and I'm guessing oversize floating disk.

 

IMO floating disks have no place on dirt bikes.

You might want to spray some WD40 onto the floating pins and make sure they float freely.

 

 

I've never used a floating disc, and it may be that since it floats and is not held in a 'as true circle' as a standard disc, it may drag a little more on the pads.

 

Remove your brake pads, and the caliper should slide easily back and forth on the pins.  If so, it may just be the characteristics of that setup.

 

For safety reasons, I would take it to the track and work the front brakes as usual.  After a bit of riding, throw it up on the stand and see if the drag has increased , or stayed the same. 

 

If it has increased, I would dig deeper, if it has stayed the same, you're probably ok, but definitely keep an eye on it. 

 

A front fender grab over a jump ain't good.  :cripple:

 

Guys I mentioned in my original post that it IS an oversized rotor (280mm) and that it is NOT floating. The disc IS NOT floating. I had this exact same disc on my last bike, and I've had it on my current bike since the first ride. I know exactly how it should be performing, and, as I mentioned, it's only started dragging after a crash. In case you doubt the aftermarket brake, it's a MotoStuff (formally CRFStuff) 280mm blade brake. Almost identical to the ones used on the US factory Honda teams bikes.

I appreciate the help guys, but we go in circles when you don't read the info properly.

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you didn't mention you have an aftermarket and I'm guessing oversize floating disk.

IMO floating disks have no place on dirt bikes.

You might want to spray some WD40 onto the floating pins and make sure they float freely.

He's using a non-floating CRF Stuff rotor. Same as the Geico Honda team uses.

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So far I still think the pins must be slightly bent, so not a huge lot of progress haha. I've ordered a replacement large pin, but the small pin cant be ordered without ordering a whole new bracket. If I need to i'll see if I can make the small pin any straighter. Failing all that, I might recondition the calliper but I think it shouldn't need it. my last bike ('10 crf250r) literally did over 180hrs and never had a problem with the brakes, so I'd be surprised if my new one needs new seals after just 45hrs.

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