Leaking Shimano brake piston seals?

Hi,

I’ve had a problem for the last few months where brakes will be working fine one day: new pads, cleaned rotors, cycles on a hill to bed them in. Leave the bike in the garage for a week or two (yes, this sucks) and the pads are contaminated, massive squeals and almost no stopping force. Initially I suspected leaking a leaking hose and double-checked that I’d tightened those up when I last bled, but then a friend pointed out it could be the piston seals weeping.

So, mighty fount of knowledge, are the piston seals on a ~2010 Shimano Deore XT brake calliper replaceable, by a mortal or by a LBS?

Cheers
Ross

It’s not particularly difficult to take the calliper apart to get at the seals – see a thread I started on MTBR about how to do it here (not 2010 XT but similar).

However, the problem is that Shimano don’t supply seal kits, so if its more than just a bit of grit in the seal and they need to be replaced rather than just cleaned, your stuck!

But before you jump to the conclusion it’s leaking seals, have a look at this thread where a lot of people seem to be having the same problem, and it’s not related to leaking oil…

That thread doesn’t really have a conclusion does it 🙂 I’ve checked the hose/calliper connection, but I have found greasy dirt between the pads and pistons so that’s definitely by favourite theory so far.

I’ve just noticed that CRC has a current Deore pair for 65 quid…

got some deores that seem to have the same problem, clean everything up, sand the pads and they work fine for a ride or two then they’re rubbish again (front only rear is ok). Tried different pads same thing happens.
TBH was wondering if it’s due to the worn disc I was using (worn from a different set of brakes – running finger radially across the disc surface you can feel the wear) could the uneven brake surface cause the pads/pistons to “rock” slightly during operation and weep fluid?

Switched em to my SS a while back and haven’t ridden it for ages, will see.

I’m sure I’ve seen some people selling their own seal kits for Shimano brakes on Fleabay, but Shimano themselves don’t offer them as spares.

Typically you end up buying a replacement calliper or (Probably more likely) a whole new brake, assuming it’s out of it’s warranty period…