Seized caliper piston. Is it worth trying to free it

Gubbins

Esteemed Pedelecer
I have been having brake issues for a while now in that sometimes its really good and sometimes not. Today Is a not and applying the brake I can see one piston moving the disk over to the other which is stationery.
So am I wasting my time messing with it? Is it worth paying a pro to sort it or just buy a new one?
 

Woosh

Trade Member
May 19, 2012
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it only takes a couple of minutes to fix. Just loosen the two bolts, move the caliper so that the pad which is not seized is against the rotor. Tighten the bolts.
Squeeze the brake lever. The fluid pressure will free the seized caliper.
Recentre the caliper.
 

Gringo

Esteemed Pedelecer
Jun 18, 2013
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Northampton
Well it all depends on what you have,
are your brakes expensive to replace ?
A seal/piston kit, new fluid and bleed kit lets you strip and rebuild them ?

Personally I'd just buy new as my Shimano brakes (single sided) were less than £40 the pr, complete, pre bled and ready to fit. It would be a different story if they were expensive ;)
 

Gubbins

Esteemed Pedelecer
Well it all depends on what you have,
are your brakes expensive to replace ?
A seal/piston kit, new fluid and bleed kit lets you strip and rebuild them ?

Personally I'd just buy new as my Shimano brakes (single sided) were less than £40 the pr, complete, pre bled and ready to fit. It would be a different story if they were expensive ;)[/QUOT
 

Gubbins

Esteemed Pedelecer
Just looked on line and there are diffent ones so will need to check. Not interstted in stripping down as a total failiur after my messing could be painful. so will try the moving the caliper thing and see if that works.
 

Nealh

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Aug 7, 2014
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£30 or so for a new calliper plus oil etc, new pistion kit about £9 each. Problem with calliper repair's if it doesn't work you have wasted money, at least with a new calliper you get new pads as well.
 

Nealh

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Aug 7, 2014
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As long as a calliper uses the same pads in theory you should be able to fit aand use any of the SLX range.
Bikester £23.99 on sale at the mo.
 

Gubbins

Esteemed Pedelecer
It would probably cost much more for bike shop to fix it and as I am not up to bleading will have to buy one already bled. just make sure the length is right.. Spent a lot over crimbo so trying to be good. tilll I pay my card off.
 

Denis99

Pedelecer
May 26, 2016
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Had this problem in the past.

Remove the pads, remove the wheel.

Make a clamp from a piece of wood that sandwiches the ( moving piston ) and the outside of the calliper.

Push the moving piston in as far as you can. Tighten up the clamp you have made, this will stop the moving piston from moving.

Now, slowly press the brake lever to get the seized piston to move.

Get an old toothbrush and clean the protruding section of the piston(s) .
Push back in, repeat this process until the once seized piston is free.
 
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Gubbins

Esteemed Pedelecer
Had this problem in the past.

Remove the pads, remove the wheel.

Make a clamp from a piece of wood that sandwiches the ( moving piston ) and the outside of the calliper.

Push the moving piston in as far as you can. Tighten up the clamp you have made, this will stop the moving piston from moving.

Now, slowly press the brake lever to get the seized piston to move.

Get an old toothbrush and clean the protruding section of the piston(s) .
Push back in, repeat this process until the once seized piston is free.
Thanks.
I had sort of guessed it's a case of getting it moving without popping the other side out. Just figuring how to do it.
 

Denis99

Pedelecer
May 26, 2016
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Cool, Never had much success using the rotor method. Found that the rotor was too flexible, and sometimes created a bit of a warp in the rotor.
 

EddiePJ

Esteemed Pedelecer
Jul 7, 2013
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It a shame that you didn't live locally to me, as I would offer to help you.

Try the advice that Denis99 has kindly offered, but if you get really stuck, I have a new take off XT caliper that I would happily give to you, but I have robbed the pads from it. I needed a lever assembly in a hurry, and frustratingly had to buy the whole assembly as there was no UK stock at the time.
My one hesitation is that I don't know if the internal ratio assembly and bore of the master cylinder/lever is the same on SLX as it is on an XT assembly, which could mean that there might be an issue compatibility between the two systems.

Also by the time that you have bought a bleed kit and pads, it wouldn't really be a viable option.

Anyway, the offer is there if you want it.

 
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Gubbins

Esteemed Pedelecer
It a shame that you didn't live locally to me, as I would offer to help you.

Try the advice that Denis99 has kindly offered, but if you get really stuck, I have a new take off XT caliper that I would happily give to you, but I have robbed the pads from it. I needed a lever assembly in a hurry, and frustratingly had to buy the whole assembly as there was no UK stock at the time.
My one hesitation is that I don't know if the internal ratio assembly of the master cylinder/lever is the same on SLX as it is on an XT assembly.
Also by the time that you have bought a bleed kit and pads, it wouldn't really be a viable option.

Anyway, the offer is there if you want it.

[
Bleeding and fitting the pipes us a step too far for me
 

soundwave

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May 23, 2015
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