Rear brake stays locked when pedal released

Please help, cage driving is driving me crazy!!

Problem statement:
I recently changed a bad brake line (don't ask) on my rear brakes. Replaced the rear pads too while I was at it. Followed the manual's bleed procedure. Got it to the point I could ride it, but rear brakes still squishy. Note: brakes not sticking at this point. I figured that air would make its way up to the bleed valve that is right under the seat/tank on the PCV, I cracked that and pumped some air out till it stopped. Checked pedal and good and firm. Went around block, bike braked good but noticed brakes dragging (trying to coast resulted in a reasonably quick stop). Got back, cracked the PCV bleed valve again and some fluid came out. Checked reservoir, still plenty. Tightened bleed valve. Pushed pads back into caliper (they stayed), then pushed pedal and the pads locked up on the rotor and did not release. This is where I'm at, any ideas? BTW, beer and lack of sleep do not help one bit!

Side note:
I finallly figured out how to get the rear wheel off without unbolting my passenger peg and exhaust. Put it on center stand and remove the brace between swing arm and caliper, then you can finagle (sp?) the wheel around. I have a high mount staintube, so not sure about other exhausts.

There's a return hole that the m/c piston may be covering and it not allowing the fluid to return to the resevoir when the brakes heat up.  The dragging brake pads could be heating up the brake fluid and since it doesn't have a way to expand back into the resevoir it is pushing the caliper pistons harder into the rotor generating more heat and more pressure until it locks up.  Does it loosen up after the brakes have cooled?

Either the caliper needs a rebuild, or the rubber hose is going bad ( Colapsed ), that is the only two things that will keep pressure on the brakes.

[image: View Post]Rush2112, on 15 June 2012 - 10:26 PM, said:

There's a return hole that the m/c piston may be covering and it not allowing the fluid to return to the resevoir when the brakes heat up.  The dragging brake pads could be heating up the brake fluid and since it doesn't have a way to expand back into the resevoir it is pushing the caliper pistons harder into the rotor generating more heat and more pressure until it locks up.  Does it loosen up after the brakes have cooled?

Could something similar happen without the heat? Because this all happens when it's cool. I'm able to press the pads back (by hand) and they stay apart so i can get em back on the rotor, but when i press brake pedal they clamp and lock.

[image: View Post]staintube, on 16 June 2012 - 08:59 AM, said:

[image: View Post]Rush2112, on 15 June 2012 - 10:26 PM, said:

There's a return hole that the m/c piston may be covering and it not allowing the fluid to return to the resevoir when the brakes heat up.  The dragging brake pads could be heating up the brake fluid and since it doesn't have a way to expand back into the resevoir it is pushing the caliper pistons harder into the rotor generating more heat and more pressure until it locks up.  Does it loosen up after the brakes have cooled?

Could something similar happen without the heat? Because this all happens when it's cool. I'm able to press the pads back (by hand) and they stay apart so i can get em back on the rotor, but when i press brake pedal they clamp and lock.
Doesn't sound like it.  If you can push the caliper pistons back in by hand the fluid is returning.  Is there any binding in the pedal or linkage?  Anything to keep it from returning?

Pistons gunked up?

If the above mentioned things check out OK you need new caliper seals. Mine were deformed enough that they were causing the pistons to stick. I replaced 'em when I did my new lines, and all is well now.

Yea sounds like the caliper needs rebuilt, pistons cleaned and polished, new seals, slider pins cleaned and greased with high temp brake grease.

One other thing. I did something similar on my CBR & it turned out I didn't have the anti-rattle retainer clip seated properly. Like you I took it apart numerous times, bled em, rode & checked, don't know how many bloody time I cooked my fingers checking the disc. Realised the clip warped as the pads made contact with the disc just enough to keep them there.

Had the same happen on one of my old Honda's and turned out to be the master cylinder.  I was very bad and did not change the fluid for a very long time.  Rebuild kit was cheap and easy.

Either the caliper needs a rebuild, or the rubber hose is going bad ( Colapsed ), that is the only two things that will keep pressure on the brakes.

i replaced the brake line at my work and rode it home with no issues except the rear brakes were pretty squishy with little stopping power on the back end. could the rubber hose just go bad all of a sudden? and/or same for caliper seals going bad?

One other thing. I did something similar on my CBR & it turned out I didn't have the anti-rattle retainer clip seated properly. Like you I took it apart numerous times, bled em, rode & checked, don't know how many bloody time I cooked my fingers checking the disc. Realised the clip warped as the pads made contact with the disc just enough to keep them there.

i think my spring is okay. i would think a warped spring wouldn't be able to put such a tight grip. i mean, its locked as if the brake pedal is still on.

There's a return hole that the m/c piston may be covering and it not allowing the fluid to return to the resevoir when the brakes heat up. The dragging brake pads could be heating up the brake fluid and since it doesn't have a way to expand back into the resevoir it is pushing the caliper pistons harder into the rotor generating more heat and more pressure until it locks up. Does it loosen up after the brakes have cooled?

Could something similar happen without the heat? Because this all happens when it's cool. I'm able to press the pads back (by hand) and they stay apart so i can get em back on the rotor, but when i press brake pedal they clamp and lock.

Doesn't sound like it. If you can push the caliper pistons back in by hand the fluid is returning. Is there any binding in the pedal or linkage? Anything to keep it from returning?

no binding in the pedal, wondering if Sweeper is right about the MC giving out. its also possible i have gunk in the system, from pistons to the cylinder. starting to think a total rebuild is necessary.

Either the caliper needs a rebuild, or the rubber hose is going bad ( Colapsed ), that is the only two things that will keep pressure on the brakes.

i replaced one of the hoses because the previous owner decided to mount the brake lines BETWEEN the chain and his custom chaingard. i failed to pick this up and as my chain loosened a bit it started chewing thru the line. i narrowly avoided a disaster! anywho, how do i check the other line that i did not replace to see if it is bad? what symptoms would a collapsed hose show?

+1 on the master cylinder.

What did it end up being?

i replaced one of the hoses because the previous owner decided to mount the brake lines BETWEEN the chain and his custom chaingard.

Yikes! He didn't know a bad idea when he saw one???

That's a downright sketchy install!!!

Thanks for all who have responded. I've been through everything mentioned and tracked it down to the PCV. Not being too familiar with it I took it into the shop and the mechanic verified that the PCV was bad. Well, its just gonna sit at the shop now because that part is on backorder. I haven't ridden since June and am about ready to fly to Japan to find a part.... Gotta love OEM-only parts... Cheers guys

...verified that the PCV was bad. Well, its just gonna sit at the shop now because that part is on backorder.

You don't need a new part, you just need A part. Start looking online for motorcycle junkyards, maybe post a Wanted ad on the forum. Someone has a parts bike lying around somewhere - you'll be able to find it.

Good luck!

Thanks for all who have responded. I've been through everything mentioned and tracked it down to the PCV. Not being too familiar with it I took it into the shop and the mechanic verified that the PCV was bad. Well, its just gonna sit at the shop now because that part is on backorder. I haven't ridden since June and am about ready to fly to Japan to find a part.... Gotta love OEM-only parts... Cheers guys

http://www.ebay.com/...d1174cf&vxp=mtr

19 dollars Vs the new price which is:

VALVE ASSY. [image: Posted Image] [image: Posted Image] No Picture. SKU: 641858 Mfg. Part Number: 46200-MBG-026

Your Price: $222.16

MSRP: $310.71

You Save: $88.55

I have a PCV in perfect working order you can have for the price of postage, unfortunately I'm in the UK & its a heavy little lump. I can price up postage if you like ?

Actiually I just measured & weighed it & packed it, total = 250grams packed so no bad. I priced it up at 25UKP so approx 40USD 3+ days via fedex.