XTR M9120 brake cal...
 

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XTR M9120 brake callipers - cracked ceramic piston

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Think I’ve cracked a piston. Was bleeding brakes and forgot to pop a block in, went to push piston back and heard a crack. Finished bleeding (with block in), closed everything up and gave the lever a good squeeze, oil pishing out the calliper 😔

Can these be replaced? Easily?


 
Posted : 26/08/2022 2:24 pm
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Well that was an expensive mistake. Called LBS who checked for me, XTR caliper is a replaceable unit - you can't just replace the pistons which is frankly ridiculous IMO. I see there are third party replacement parts on eBay but not sure I'd want to take the risk of a front brake failing at the wrong time.


 
Posted : 26/08/2022 3:19 pm
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Yep, welcome to Shimano brakes. At least you'll have some spares from the old caliper now...

Your other alternative is to find a broken caliper for sale somewhere.


 
Posted : 26/08/2022 3:22 pm
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IIRC there was some options for pistons on fleebay, obviously no idea on quality etc but might give you an option if Shimano have none or no availability.

James


 
Posted : 26/08/2022 4:46 pm
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Warranty issue? Shouldn’t have cracked from just being pushed in surely??


 
Posted : 26/08/2022 5:45 pm
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Shouldn’t have cracked from just being pushed in surely??

They're ceramic so unless you use a rubber coated spanner handle they'll crack. Been there done that!


 
Posted : 26/08/2022 5:51 pm
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Done the same to slx single pistons. Used ebay alloy piston kit - worked fine.
May not be as good at heat dissipation due to part of the caliper being alloy rather than ceramic.


 
Posted : 26/08/2022 6:03 pm
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Did that on a mtb holiday once on the first night. I just stared, dumbfounded at my brake for about 15 minutes. Just couldn't even process what had gone wrong. To be fair, my piston had cracked while riding (weird vibration during first ride of the holiday, hence why I was bleeding my brakes). You have my sympathy


 
Posted : 26/08/2022 6:48 pm
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I did that with an old set of xtr..bought an slx calliper cheap and used the pistons and seals from that. Don't know if you can do it with the new ones


 
Posted : 26/08/2022 10:09 pm
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Yes - SLX or XT would make a cheaper donor.


 
Posted : 27/08/2022 6:34 am

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