Rear Brake Dragging

[shamrocker]

Hey guys, I'm experiencing some brake dragging on my rear wheel. When I get back from a ride, the rear rotor is hot to the touch. There is also some discoloration, similar to the problem described in http://www.600riders.com/forum/gara...6-please-help-new-bike-rear-brake-issues.html I've checked and rechecked the wheel alignment, greased the pins, checked the torque on the caliper bolts, cleaned the pads and the problem still occurs. The rear brake seems to work normally and it doesn't seem to affect the bike otherwise, just making the rotor hot. I gather that the next thing I need to do is bleed the brake and change fluid? I'll probably change the pads, too... Am I on the right track here?

 

[FZ6Firefighter5]

Well I would check to see if your rear caliper is siezed and wont release. How id go and check that is first loosen the bleeder and then squeeze the caliper piston back with a pair of pliers and see if it moves if it dosent then you need a new caliper and id deffenently replace the brake pads and possibly the rotor.

 

[shamrocker]

Cool, thanks. I did what you said and the piston moves fine. Any others have ideas?

 

[necrotimus]

Has it always done this? Did you recently change anything?

Shots in the dark:

A parts shop once gave me the wrong brake pads for a car. They looked EXACTLY the same but were too thick.

Make sure you aren't resting you toe on the brake. Depending on your ergonomics on the bike you may not even realize you are doing it.

 

[madmanmaigret]

If the bike is on the center stand (with you not on it) spin the rear wheel. There will be some resistance due to the chain/sprockets, but does the rear brake still rub? If yes, have you recently put new pads on (for reason stated above)? Is the rear caliper "carrier" (bracket that caliper is mounted to that slides into the "nub" on the rear of the swingarm) correctly aligned? Is the wheel/tire correctly aligned?

You have checked everything else I would if nothing else pans out.... I would bring it to the shop.

 

[Cali rider]

Remove the caliper then remove the piston and seals. Clean the bore of the caliper and the surface of the piston with a fine Scotch-Brite pad. Install new seals and re-install piston. Flush old brake fluid, bleed and try it out on the road.

 

[madmanmaigret]

Remove the caliper then remove the piston and seals. Clean the bore of the caliper and the surface of the piston with a fine Scotch-Brite pad. Install new seals and re-install piston. Flush old brake fluid, bleed and try it out on the road.

If all else fails.....this is what you are left with. Be careful removing the pistons if you have never done it before......it can really hurt you!

 

[shamrocker]

Thanks guys. Yes, it has done this since I bought it a couple weeks ago. I haven't changed anything, but I am going to try new pads and bleeding the brake. I've never disassembled a caliper piston before, so I may leave that to a pro if it comes to that. I swear everything else looks like it's normal. I've readjusted the rear alignment several times with several methods, but there is still some resistance as I spin the back wheel.

 

[shamrocker]

Also, is it possible to bleed the rear brake without a Mityvac-type device? I.E. Pushing the brake pedal and connecting a clear hose to the bleeder?

 

[dako81]

Also, is it possible to bleed the rear brake without a Mityvac-type device? I.E. Pushing the brake pedal and connecting a clear hose to the bleeder?

Yes, but it will be easier with two people if you go that route. And make sure you follow the correct order of operations:

Once everything is all ready (resivoir cap off, tube in place and end into container, etc.),

1) have them depress the pedal
2) open bleeder to release pressure, make sure they do not lift up and keep applying constant pressure, no pumping or lifting
3) close bleeder
4) have them release
5) repeat

And, make sure the resivoir does not get empty.

 

[urbanj]

Also, is it possible to bleed the rear brake without a Mityvac-type device? I.E. Pushing the brake pedal and connecting a clear hose to the bleeder?

Yes. Do it just they way you said. don't need two people cause it's all on the same side.

is the brake adjusted right?

 

[dako81]

Yes. Do it just they way you said. don't need two people cause it's all on the same side.

is the brake adjusted right?

Yea but it will require some fancy footwork, or good left hand skills with the wrench. If you slip, you've just sucked some air into the system and will have to spend more time bleeding it out.

 

[shamrocker]

Yes. Do it just they way you said. don't need two people cause it's all on the same side.

is the brake adjusted right?

What do you mean by adjusted right? Could there be something too tight on the brake cylinder or pedal?

 

[necrotimus]

Yea but it will require some fancy footwork, or good left hand skills with the wrench. If you slip, you've just sucked some air into the system and will have to spend more time bleeding it out.

I haven't yet worked on my bikes brakes, spring project, so I don't know if it is the same but to prevent air getting back into the system you can attach a piece of flexible plastic hose to the bleeder. There will be fluid left in the hose and it will pull fluid in not air.

 

[urbanj]

There is an adjustment on the linkage and the threaded portion of the master cylinder plunger. I'd just check and make sure that even when the pedal is fully release that the plunger is all the way out and not applying pressure. it could be ever so slight pressure but it's worth to check. or disconnect the pedal completely and see if you notice a difference in drag.

The square cut seals in the caliper will only retract it so far. but there has to be no pressure applied.

 

[shamrocker]

UPDATE: Yesterday, I installed some new EBC pads and bled the brake line with new DOT4 fluid. The old fluid was definitely a darker yellow color. One of the original pads was slightly warped and bowed(specifically the thick metal that the pad material is attached to) so that couldn't have been helping matters. The pad material was also crumbling around the edges. After finishing all of the work, I took her out for a spin and tried to bed the brakes in properly. When I got home, I was pleasantly surprised to feel the rotor was significantly cooler than normal. It wasn't perfectly cool, like the front rotors, but I could tell a big difference. It seems maybe the new pads might rub a little bit until they're broken in, is that right? Anyway, I'm really excited that I may have tackled this issue on my own. Since the rotor appears to be in good operating condition, is it possible to clean up the discoloration, perhaps by having it turned? I hate to spend the $75 on a new rotor from the dealer, but it does look sorta bad.

 

[shamrocker]

Still pretty hot after a long ride but can it be because of the new pads?

 

[damnpoor]

Did you ever mic the rotor to make sure it's the right thickness? When you slid the caliper back on over the rotor was it a super tight fit?