80 Wide glide rear brake problem
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80 Wide glide rear brake problem
Hey, I just bought a 80 wide glide shovelhead. The old owner said the rear brake assembly was just replaced. Anyway, I rode it a couple miles and the rear brake pedal got hard and the rear brake started dragging. I cracked open the bleeder valve to let off some pressure and the pedal returned back to normal and the brake quit dragging. Took it out again and same problem.....this has happened three times in a row now....each time I crack the bleeder valve. What is the problem? I thought eventually it would quit considering the excess fluid drains each time.....any idea?
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I know saying "overfilled with fluid" kinda sounds like an answer, but if you stop and think for just a sec, you will realise that is not even possible.
And even if it were, which it is not, the moment you opened the bleeder, the issue would be solved, and the problem would not return.
So we know that is not it.
Now, provided that the brake has previously functioned correctly, and has not been touched........
Then what it actually is.............
Is a problem in the master cylinder.
The fluid is clearly unable to return to the master cyl.
Once you have pumped the brakes a few times, the pressure builds up, and the brake drags.
Opening the bleeder temporarily relieves the issue, then the process starts all over again.
It is most likely gunk and stuff that can build up, and block the little return port.
You need to pull it apart, and clean it right out.
You may even want/need to put a kit in it.
If it were the caliper piston sticking in the seal, opening the bleeder would not help.
And even if it were, which it is not, the moment you opened the bleeder, the issue would be solved, and the problem would not return.
So we know that is not it.
Now, provided that the brake has previously functioned correctly, and has not been touched........
Then what it actually is.............
Is a problem in the master cylinder.
The fluid is clearly unable to return to the master cyl.
Once you have pumped the brakes a few times, the pressure builds up, and the brake drags.
Opening the bleeder temporarily relieves the issue, then the process starts all over again.
It is most likely gunk and stuff that can build up, and block the little return port.
You need to pull it apart, and clean it right out.
You may even want/need to put a kit in it.
If it were the caliper piston sticking in the seal, opening the bleeder would not help.
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thats one of the problems, I don't know for sure If the brakes were previously doing this or not.....I just bought the bike and the previous owner just said that the rear brake was JUST replaced....
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That could change things.
Was there any master cyl work????
I think there may well have been.
There is a small hole in the m/cyl that allows the fluid to move back and forward between the bore and the reservoir.
If the wrong kit is installed, and the rubber boot is too long, or too far forward, so that it covers the hole, the fluid can only pass one way.
This is easy to check, if you have a combination reservoir/bore m/cyl.
With the lid off, if you press the pedal quick, you should see a jet(possibly small, but maybe large, so take care) of brake fluid shoot up into the reservoir. This is the fluid being displaced before the boot passes the hole, and pressurization commences.
Of course, if the boot is already past the hole, there will be no jet at all.
You need to check a few things.
Tourer
Joined: Jul 2007
Posts: 260
Likes: 1
From: Missoula MT
Check and make sure that the brake pedal is returning all the way to rest and that when it is, there is slack in the m/c push rod. Meaning that the piston in the m/c is all the way back to its home position. You should be able to adjust the rod to obtain a little slack. Don't need much, 1/16" or so will work fine. JMHO, YMMV, etc. Congrats on the wide glide, I would like to find one like that. We need pix. What did you give for it if you don't mind?
Bob
Bob
Last edited by Greybeard Bob; Mar 17, 2010 at 10:54 AM.
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Road Master
Joined: Jun 2008
Posts: 1,078
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From: NW Florida
Another thing to check is if the rear disc is warped. A warped disc will drag and create heat and cause the problem you describe. Prop up the rear of the bike and spin the tire. tape an indicator rod to a suitable location and see if the disc has any run out. The early boomerang caliper mount could also be bent causeing the drag. They made a tool for straightening it but I don't know where you will find one.
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Ok
That could change things.
Was there any master cyl work????
I think there may well have been.
There is a small hole in the m/cyl that allows the fluid to move back and forward between the bore and the reservoir.
If the wrong kit is installed, and the rubber boot is too long, or too far forward, so that it covers the hole, the fluid can only pass one way.
This is easy to check, if you have a combination reservoir/bore m/cyl.
With the lid off, if you press the pedal quick, you should see a jet(possibly small, but maybe large, so take care) of brake fluid shoot up into the reservoir. This is the fluid being displaced before the boot passes the hole, and pressurization commences.
Of course, if the boot is already past the hole, there will be no jet at all.
You need to check a few things.
That could change things.
Was there any master cyl work????
I think there may well have been.
There is a small hole in the m/cyl that allows the fluid to move back and forward between the bore and the reservoir.
If the wrong kit is installed, and the rubber boot is too long, or too far forward, so that it covers the hole, the fluid can only pass one way.
This is easy to check, if you have a combination reservoir/bore m/cyl.
With the lid off, if you press the pedal quick, you should see a jet(possibly small, but maybe large, so take care) of brake fluid shoot up into the reservoir. This is the fluid being displaced before the boot passes the hole, and pressurization commences.
Of course, if the boot is already past the hole, there will be no jet at all.
You need to check a few things.