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Shimano hydraulic sticky pistons; HELP!

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Shimano hydraulic sticky pistons; HELP!

Old 11-27-22, 03:58 PM
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rbrides
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Shimano hydraulic sticky pistons; HELP!

I'm at my wits-end to get my front brake piston to release back into the caliper when I release the brake leaver while riding. I've cleaned it 7-8 times following Park Tools (and Bike forums) advice, and all other recommendations, but to no avail
When riding and I apply front brakes and release the handle the brake squeal is excessive. I always have to pump the lever 4-8 times to work it lose and the squeal goes away, but that is no way to ride. I'm considering buying a rebuild kit to replace the pistons and seals but don't see any for sales nor do I see that as a commonly recommended procedure to fix sticky pistons. I've tried everything I know or which has been recommended. HELP.

Any advice?

Last edited by rbrides; 11-27-22 at 04:06 PM.
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Old 11-27-22, 04:43 PM
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Originally Posted by rbrides View Post
I'm at my wits-end to get my front brake piston to release back into the caliper when I release the brake leaver while riding. I've cleaned it 7-8 times following Park Tools (and Bike forums) advice, and all other recommendations, but to no avail
When riding and I apply front brakes and release the handle the brake squeal is excessive. I always have to pump the lever 4-8 times to work it lose and the squeal goes away, but that is no way to ride. I'm considering buying a rebuild kit to replace the pistons and seals but don't see any for sales nor do I see that as a commonly recommended procedure to fix sticky pistons. I've tried everything I know or which has been recommended. HELP.

Any advice?
Pistons that won't retract sometimes indicates air behind the piston. Have you tried re-bleeding the system? Even with Shimano systems, I like to "push" from the bottom and force fluid into the cup. Often, that releases the air and get the piston moving correctly.

Also, before you do that, make sure to push the pistons back with something like the park tool - which I highly, highly recommend, and remove the pads before doing any bleeding, etc.

But if you can't get any of that to work, and the system is not too old, trying getting it warranted.
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Old 11-27-22, 06:04 PM
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rbrides
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Originally Posted by vespasianus View Post
Pistons that won't retract sometimes indicates air behind the piston. Have you tried re-bleeding the system? Even with Shimano systems, I like to "push" from the bottom and force fluid into the cup. Often, that releases the air and get the piston moving correctly.

Also, before you do that, make sure to push the pistons back with something like the park tool - which I highly, highly recommend, and remove the pads before doing any bleeding, etc.

But if you can't get any of that to work, and the system is not too old, trying getting it warranted.
I will give that a try.
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