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Brakes locking up.
#412154 11/14/2010 2:41 PM
Joined: Mar 2007
Posts: 373
Bruce Offline OP
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First I want to thank everyone here for the help doing my first valve shimm check. I had to change most of the shimms but now everything is within spects. Now for my next help subject. I have a 1981 Honda Silverwing that has a brake problem. When the bike sits over night the front brake pistons seat against the rotors and I have to bleed some brake fluid out of the calipers to let the pistons retract and let the wheele turn. After the bike sits again over night I will have to do the same thing even though no one has touched the brake lever. The pistons do retract when I use the brake lever but if the bike sits for any length of time those pistons are against the rotors. Any thoughts?


'06 America, Raask foot controls, the bike use to be Graphite and Silver, now its Red and Black.
Re: Brakes locking up.
Bruce #412155 11/14/2010 5:51 PM
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Loquacious
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I think your front master cylinder might be sticking. Check the piston that your brake lever pushes to see if it is coming all the way back. When was the last time the brake fluid was changed? Was any other fluid put in the reservoir other than DOT4 fluid. Try flushing the system.


12 Rocket Roadster
03 Bonneville America
69 BSA Firebird Scrambler
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Re: Brakes locking up.
Gregger #412156 11/14/2010 6:04 PM
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Stickman Yogi
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I was thinking the piston could have a little rust on it. Bruce, have you tried repeating a squeeze/release on the brake handle (before bleeding) which might help loosen things up?


Live to love, love to live.
Re: Brakes locking up.
Keith #412157 11/14/2010 7:10 PM
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Learned Hand
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If that doesn't work check the piston. If the piston and both rubber cups are ok then check the supply and relief ports in the master cylinder and make sure they're not blocked. more so the relief port than the supply port.....Angelis


1200CC BIG BORE, W/WISECO PISTONS,.250 STROKED CRANK, PORTED/POLISHED HEADS AND LARGER VALVES, CUSTOM WELDED EXHUAST, DUAL 42MM MIKUNI CARBS.
Re: Brakes locking up.
ANGELIS745 #412158 11/14/2010 9:09 PM
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Oil Expert
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Could be that the pistons have developed a minor taper, either through wear on the inner end or rust/dust/gunk accumulation on the other, or both. The pressure of the sealed hydraulic system added to the pressure of the seals acting against the tapered edge of the pistons could be enough to move the brake pad against the disk over time. Take the pistons out, clean them up, and check them with a micrometer.

Re: Brakes locking up.
Sandmann #412159 11/21/2010 10:47 AM
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Second Wind
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Well its a very old system there. Its an 81 which means its 29 years old. If the bike has ever sat up for any length of time that is the source of your problem. Brake fluid is very corrosive and will very quickly deteriorate the system you need to take the thing off and clean it up. Your rubber sills ARE swollen up and are sticking. Also you may have some corrosion in your relief port in your Master cylinder, along with some quite possibly in your lines.


The rubber seals in the wheele cylinder ARE the biggest part of the problem as they are swollen up, and will be difficult to find. note the word difficult not impossible. You may find they are the same as some foriegn car out there.

Last edited by locopony; 11/21/2010 10:53 AM.

I have no faith in human perfectability. I think that human exertion will have no appreciable effect upon humanity. Man is now only more active - not more happy - nor more wise, than he was 6000 years ago. Edgar Allan Poe

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