Front brake Heritage sticks
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Tourer
Joined: Feb 2015
Posts: 296
Likes: 40
From: Holland
Front brake Heritage sticks
1992 Heritage, stock single piston caliper:
Caliper is clean, slides well and the piston is clean as well.
Rubber all in one piece, when I peel that down the piston is clean as well.
Fluid is still fresh(ish) and master is on the mark, not overfilled.
Now when I press the lever the piston comes out and when I release it goes straight back in, which it should, but the starting position is like 10 tot 15 mm out so with the pads in the brake sticks...
For some reason I can't depress the piston in any further...so what am I missing?
Caliper is clean, slides well and the piston is clean as well.
Rubber all in one piece, when I peel that down the piston is clean as well.
Fluid is still fresh(ish) and master is on the mark, not overfilled.
Now when I press the lever the piston comes out and when I release it goes straight back in, which it should, but the starting position is like 10 tot 15 mm out so with the pads in the brake sticks...
For some reason I can't depress the piston in any further...so what am I missing?
Dirt don't hurt
Joined: Jan 2011
Posts: 21,066
Likes: 4,567
From: Haslet Texas
1992 Heritage, stock single piston caliper:
Caliper is clean, slides well and the piston is clean as well.
Rubber all in one piece, when I peel that down the piston is clean as well.
Fluid is still fresh(ish) and master is on the mark, not overfilled.
Now when I press the lever the piston comes out and when I release it goes straight back in, which it should, but the starting position is like 10 tot 15 mm out so with the pads in the brake sticks...
For some reason I can't depress the piston in any further...so what am I missing?
Caliper is clean, slides well and the piston is clean as well.
Rubber all in one piece, when I peel that down the piston is clean as well.
Fluid is still fresh(ish) and master is on the mark, not overfilled.
Now when I press the lever the piston comes out and when I release it goes straight back in, which it should, but the starting position is like 10 tot 15 mm out so with the pads in the brake sticks...
For some reason I can't depress the piston in any further...so what am I missing?
All it really does is take the pressure off the brake pads but the pads will remain in contact with the rotor.
Have you tried it mounted to your bike?
Do the brakes drag???
If the brakes are maintaining pressure on the rotor then you will probably need to clean out the return passage in the master cylinder.
Or hell just clean entire master cylinder.
Last edited by texashillcountry; Oct 17, 2017 at 05:40 PM.
Seasoned HDF Member
Joined: Apr 2011
Posts: 6,185
Likes: 2,134
From: W. Texas
The seal around the piston is square not round. As the lever is pulled the piston moves out so slightly and rolls the square seal (oring) with it. While applying the pads to the rotor.
When lever is released the square seal helps to retract the piston ever so slightly. That's how the pads release the rotor to turn. Then the rotor spinning helps to push the pads a little more for complete release.
WP
When lever is released the square seal helps to retract the piston ever so slightly. That's how the pads release the rotor to turn. Then the rotor spinning helps to push the pads a little more for complete release.
WP
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Tourer
Joined: Feb 2015
Posts: 296
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From: Holland
LOL
Yes I have tried it on the bike, hence me saying the brake sticks ;-)
There was a 4-piston caliper on it which worked fine.
Took that off, swapped it for the original and hey presto: the brake sticks.
So I took it off and had a look.
Everytime you release the brakelever the piston does retract (otherwise your brakes would simply be stuck all the time untill the pads wear down), but like I said: it seems that the startingposition of the piston is too far out if that makes sense?
The master worked fine with the 4-piston caliper so can't imagine that being the problem?
Yes I have tried it on the bike, hence me saying the brake sticks ;-)
There was a 4-piston caliper on it which worked fine.
Took that off, swapped it for the original and hey presto: the brake sticks.
So I took it off and had a look.
Everytime you release the brakelever the piston does retract (otherwise your brakes would simply be stuck all the time untill the pads wear down), but like I said: it seems that the startingposition of the piston is too far out if that makes sense?
The master worked fine with the 4-piston caliper so can't imagine that being the problem?
Before you started, did you fully disassemble-clean-resemble with fresh rubber bits? (The caliper that is). If not, I'd say do that then see what's up when you're done.
When you say 'sticking', what exactly do you mean? It's the pad left putting real pressure on the rotor, or is it just dragging a little? How are you testing this?
When you say 'sticking', what exactly do you mean? It's the pad left putting real pressure on the rotor, or is it just dragging a little? How are you testing this?
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Dirt don't hurt
Joined: Jan 2011
Posts: 21,066
Likes: 4,567
From: Haslet Texas
LOL
Yes I have tried it on the bike, hence me saying the brake sticks ;-)
There was a 4-piston caliper on it which worked fine.
Took that off, swapped it for the original and hey presto: the brake sticks.
So I took it off and had a look.
Everytime you release the brakelever the piston does retract (otherwise your brakes would simply be stuck all the time untill the pads wear down), but like I said: it seems that the startingposition of the piston is too far out if that makes sense?
The master worked fine with the 4-piston caliper so can't imagine that being the problem?
Yes I have tried it on the bike, hence me saying the brake sticks ;-)
There was a 4-piston caliper on it which worked fine.
Took that off, swapped it for the original and hey presto: the brake sticks.
So I took it off and had a look.
Everytime you release the brakelever the piston does retract (otherwise your brakes would simply be stuck all the time untill the pads wear down), but like I said: it seems that the startingposition of the piston is too far out if that makes sense?
The master worked fine with the 4-piston caliper so can't imagine that being the problem?
Have you got picts?
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PS: The piston doesn't really retract on it's own. Like WP50 said, there may be a tiny amount if 'stiction' from the O-ring, but other than that, there's nothing in the system to pull it back.
What happens is that there's no such thing as a perfectly flat rotor and no such thing as wheel bearings without a little play in them. As the wheel turns, those things work to ease the pad/piston back a tiny amount. (A few thousandths of an inch) The actual amount of piston travel when you apply the brakes is minimal.
The pads can be thought of as constantly skimming the surface of the rotors. They are in contact, but with zero force. When you squeeze the lever, it's less about moving the pad than it is about increasing (from zero) the force between the pad and the rotor.
What happens is that there's no such thing as a perfectly flat rotor and no such thing as wheel bearings without a little play in them. As the wheel turns, those things work to ease the pad/piston back a tiny amount. (A few thousandths of an inch) The actual amount of piston travel when you apply the brakes is minimal.
The pads can be thought of as constantly skimming the surface of the rotors. They are in contact, but with zero force. When you squeeze the lever, it's less about moving the pad than it is about increasing (from zero) the force between the pad and the rotor.
Last edited by 0maha; Oct 18, 2017 at 06:56 AM.
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Joined: Jun 2010
Posts: 9,332
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From: Upstate New York
It sounds like youre installing new pads. You will have to physically push the piston back into the caliper to make room for the new pads. Since youre pushing fluid back into the master cylinder reservoir, you need to remove the cap from the fluid reservoirs when you do this. Then I can usually push the piston back by hand, but it takes some force. Failing that. You can use a c clamp.