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Busted rear brake cylinder


Joe85
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Changed my rear pads today and was struggling to get both cylinders back into the calliper flush. Only need a mm to get the calliper back over the disc so used two ring spanners to push the back a bit. Not excessive force by any means but one of the cylinders now has a small hole in it where the face of the cylinder has broken.



I've bought a whole new brembo calliper but it wont be here for a week, so my question is, how safe is the current one?


Tried it out and it still breaks, also no break fluid pissing out.


 

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Picture of what you mean ?

Some pistons have a separate inner damper/pad where the piston pushes on the pad ...the second from left slides into the piston and makes contact with the pad

 

947126826__3.thumb.jpg.f720ca63d98a5a6bc729d48e9c7db9f3.jpg

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Sorry no pic i've reassembled it but using your pic, the piston on the far left has a 5mm hole on the centre of the face that makes contact with the rear of the pad.



Im guessing its going to get gunked up with brake dust and detritus.


Excuse the shit picture, i've tried marking it up in the iphone but the black represents the hole



90234c253fc27a0b25c1ce340ead81be.jpeg

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Moved to the right section ;-)


If there is no fluid leaking out of it then it's probably an inner cup or something


What bike is it?

Monster 821.


The bane of my life.

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Moved to the right section ;-)


If there is no fluid leaking out of it then it's probably an inner cup or something


What bike is it?

Monster 821.


The bane of my life.

 


Looking at a parts diagram it doesn't show the brake piston!

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Just gonna have to chance it. My worry is that the piston will start to disintegrate under pressure.


Will just stay off the rear as as much as possible. Can't believe how weak the piston was. Mind you, that'll teach me to stick too ring spanners into a caliper and squeezing them together. Expensive lesson :(


Will stick some pics up when i replace it.

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I highly doubt you have put a hole in the piston they take a lot more pressure than a ring spanner and if there is no fluid leaking out then its not got a hole in it


as I said earlier I bet its an inner cup thats sat in the piston a bit like what Tim has posted above

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I highly doubt you have put a hole in the piston they take a lot more pressure than a ring spanner and if there is no fluid leaking out then its not got a hole in it


as I said earlier I bet its an inner cup thats sat in the piston a bit like what Tim has posted above

 

There's definitely a hole there, Stu. I'll put the pics up when I replace it.


Are you saying I've damaged and outer cover of the piston and not the piston itself?



Edit, i understand what you/tim are getting at now.


Will pull it back out tomorrow and have another look.

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I believe you that there is a hole but not in the piston itself


If you look at the pic Tim posted some have an inner part which I think this is what you have damaged


If it was the piston it would be leaking fluid and not work at all :thumb:

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I believe you that there is a hole but not in the piston itself


If you look at the pic Tim posted some have an inner part which I think this is what you have damaged


If it was the piston it would be leaking fluid and not work at all :thumb:

 

I concur,pistons are cup shaped with the bottom of the cup innermost. You have only damaged some kind of insert. If you had holed a piston you would have no brakes at all.

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I believe you that there is a hole but not in the piston itself


If you look at the pic Tim posted some have an inner part which I think this is what you have damaged


If it was the piston it would be leaking fluid and not work at all :thumb:

 

I concur,pistons are cup shaped with the bottom of the cup innermost. You have only damaged some kind of insert. If you had holed a piston you would have no brakes at all.

 

I understand.


Thanks all. I feel like maybe i have wasted £200 on a calliper :D

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  • 2 weeks later...

Why have you bought a whole caliper when all you needed was a piston or more likely just an insert that probably doesn't do much anyway ? By the way I've got a 25 year old GSXR that's still on the original rear pads, I should probably use the rear brake a bit more.

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