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Author Topic: rear caliper heating up and locking up disc  (Read 1568 times)

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Offline 76RD400

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rear caliper heating up and locking up disc
« on: June 25, 2010, 08:33:34 PM »
has anyone had a rear caliper heat up and lock up on the disc? i rebuilt both the master and caliper. new pistons and seals in both, plus new braided steel line.
« Last Edit: June 25, 2010, 08:34:42 PM by 76RD400 »

Offline strokestroke

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Re: rear caliper heating up and locking up disc
« Reply #1 on: June 25, 2010, 09:36:50 PM »
I totally experienced this and am very curious as to what it is as well! Switched MC - still happened eventually. Maybe something to do with the fluid? Blew motor since then, but will be revisiting it soon.
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Offline Surewin

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Re: rear caliper heating up and locking up disc
« Reply #2 on: June 25, 2010, 09:42:07 PM »
Do you have rearsets?  If so you might want to check that the linkage fully returns to release pressure on the master cylinder.

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Re: rear caliper heating up and locking up disc
« Reply #3 on: June 25, 2010, 10:41:35 PM »
yes, check linkage but usually is the return hole in the master, the tiny one, that blocks. take hose out, clean well. should be okay.
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Offline 76RD400

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Re: rear caliper heating up and locking up disc
« Reply #4 on: June 25, 2010, 10:43:29 PM »
Do you have rearsets?  If so you might want to check that the linkage fully returns to release pressure on the master cylinder.
Yes.i checked that out and i also backed off the plunger off the piston and it still locked up

Offline 76RD400

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Re: rear caliper heating up and locking up disc
« Reply #5 on: June 25, 2010, 10:46:14 PM »
yes, check linkage but usually is the return hole in the master, the tiny one, that blocks. take hose out, clean well. should be okay.

Yes i cleaned that one out when i rebuilt it. it was plugged then,  i may be taking it apart again.

Offline poppaweely

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Re: rear caliper heating up and locking up disc
« Reply #6 on: June 25, 2010, 10:58:00 PM »
that return hole is super tiny, shove some very thin wire into it.
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Offline MK

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Re: rear caliper heating up and locking up disc
« Reply #7 on: June 26, 2010, 05:21:46 AM »
A test you can do to determine whether it's the master or the caliper is get it to start sticking, then crack the bleeder open. If it releases then it is the master cylinder. If not then the caliper is sticking.
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Offline 76RD400

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Re: rear caliper heating up and locking up disc
« Reply #8 on: June 26, 2010, 01:07:43 PM »
just dissasembled the rear caliper and my new outboard seals were rolled, so will order new seals! hopefully that is it! Thanks all!

Offline cabits

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Re: rear caliper heating up and locking up disc
« Reply #9 on: June 26, 2010, 02:15:00 PM »
I had a similar problem and it turned out to be a warped rotor. As you rode the bike the warped part of the rotor would hit the brake pad and gradually heat it up. That would cause the pad to swell and the brake fluid to heat up inside the caliper and the clearance between rotor and pad went away causing it to almost seize up until it cooled off again.
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Re: rear caliper heating up and locking up disc
« Reply #10 on: June 26, 2010, 07:45:28 PM »
Happened to me about a month ago after i had taken the rearsets off for some reason. Pulled into a gas station and let it cool down and then made it home. Found the torsion spring for the brake pedal sitting in the tool caddy on my roller stool. Yup Yup Yup I'm schmart.........

Offline Makin Treehugrs Mad

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Re: rear caliper heating up and locking up disc
« Reply #11 on: June 28, 2010, 08:24:27 PM »
I've seen this happen on everything from cars to ATV's ( if it's just a sticky piston) -- sometimes you get lucky, & after the brakes cool down they work normally. Other times you have to push the piston back in with a C-clamp, then pump it back out several times .... then it will retract normally. Then, sometimes you gotta pop the piston out & start over. I always use a dental pick & really clean the hell out of the seal grooves, then check & make sure there isn't a spot of anything on the internal seal. I can usually get them working normally after some heat, or the C-clamp method though.
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Re: rear caliper heating up and locking up disc
« Reply #12 on: June 28, 2010, 08:50:09 PM »
hm. thi is why i never run the outer seals...
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Offline HeartlessMachine

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Re: rear caliper heating up and locking up disc
« Reply #13 on: June 28, 2010, 10:00:11 PM »
hm. thi is why i never use the rear brake...

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Online m in sc

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Re: rear caliper heating up and locking up disc
« Reply #14 on: June 28, 2010, 10:12:47 PM »
hehe.. very recently if it didnt  work i would have ate that ford flex's ass as the front wheel was smoking and sliding. im not kidding...
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