Rear brake seizing up
Thread Starter
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Stellar HDF Member
Joined: Mar 2007
Posts: 2,120
Likes: 192
From: Lakeland, FL
Rear brake seizing up
I just picked up a 94 fxr thats been sitting a while. When I got it home, it had no rear brake. I bled it with dot 5 and all was well until it got hot. After a couple of miles the brake seized up. I figured there must be moisture in the system, so I bled it again with the same results. Finally, I ran denatured alcohol through it and bled it with dot 5. It seemed fine last night but tightened up as I got to work again this morning. What am I missing here? The caliper retracts when it cools. Does that mean the master is bad? The first time I noticed it, sunlight was enough to put drag on the rear wheel. Any help would be appreciated.
Seasoned HDF Member
Joined: Nov 2009
Posts: 15,705
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From: Farmington ,MS
If the piston in the master doesn't return all the way it can cause this...the master can be "bad" and cause this...crack the bleeder...if that releases the pressure you have some issue with the master...
If cracking the bleeder does nothing...you have an issue with e caliper...
If cracking the bleeder does nothing...you have an issue with e caliper...
Road Master
Joined: Dec 2012
Posts: 1,240
Likes: 512
From: Getzville New York
I just went thru this with an 88 sportser that was sitting for a while, rear brake would lock up the master cylinder was caked up with gunk I rebuilt the master cylinder and the rear caliper installed a new brake line and pads everything is fine now.
My approach would be to check the entire system that crud will infiltrate the entire system
My approach would be to check the entire system that crud will infiltrate the entire system
Tourer
Joined: Sep 2017
Posts: 280
Likes: 96
From: DFW Texas
Do the pads have plenty of wear left on them? Are they flat, not tapered from one end to the other. If not, the piston could be toward its limit of travel or it gets forced crooked in the bore and locked up. Heat may play a role in that it changes the tolerances just enough, due to expansion, that the problem shows up.
If the pads are good, then the next step may be to rebuild the caliper and inspect the bore and piston. I really don't see how the master could do it unless the piston in the master gets stuck when you apply the brakes, and I would think that would be obvious as the pedal would change feel the next time you push it down.
The crud in the system is a definite possibility as well.
If the pads are good, then the next step may be to rebuild the caliper and inspect the bore and piston. I really don't see how the master could do it unless the piston in the master gets stuck when you apply the brakes, and I would think that would be obvious as the pedal would change feel the next time you push it down.
The crud in the system is a definite possibility as well.
Thread Starter
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Stellar HDF Member
Joined: Mar 2007
Posts: 2,120
Likes: 192
From: Lakeland, FL
Ill have to take a look at the pads. One thing I wish I had checked was pedal travel. The brake pedal gets very stiff. I havent checked to see if its in the up position or hasnt returned from the last press. I think Ill rebuild the master and caliper and get new pads. This bike sat for a long time before I got it Friday.
I'd replace the lines (reservoir to MC, MC to caliper) as well.
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Stellar HDF Member
Joined: Mar 2007
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From: Lakeland, FL
Is there a way I could find the line length without removing them? Id like to order parts today, but its my ride home.
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From: Texas
If the piston in the master doesn't return all the way it can cause this...the master can be "bad" and cause this...crack the bleeder...if that releases the pressure you have some issue with the master...
If cracking the bleeder does nothing...you have an issue with e caliper...
If cracking the bleeder does nothing...you have an issue with e caliper...