Can it be done? I think the cold weather has ruined them and replacing the whole caliper seems rather wasteful.

If you could buy them,yes.But you can’t so no.

Are they less than 2 years old and do you still have the receipt? If so, send em back and get them fixed/replaced under warranty. That’s what I did with mine anyway.

what do the innards look like? Can’t be much to it. Surely you can just get some normal o-rings or are they special? Keen to know as just about to do an oil change on my 775s and hoping I don’t find anything sinister.

They are special seals – a fancy squarish section O ring and no spares are available from shimano and as far as anyone has been able to find out they are not an off the shelf seal.

Do any of the cheaper calipers use the same seals??

I believe so – you need one with the same diameter pistons – northwind did work this out.

I didn’t work out every compatible brake but I’m told all the equivalent models- that year’s deore and SLX- are compatible. I used an older (960) XTR caliper myself.

It’s a total pain tbh. Usually someone will post in these threads that spares are available “if you know where to look” or similiar but nobody ever seems to know where that might be. Annoys me, so unneccesary- but it’s not the end of the world.

Its a square seal with a lip on it

Ive tried doing it with a standard square seal after i took the original to the bearing/seal factors and he said nah mate nothing like that but i have these ……

Didnt work very well !

apparantly shimano never go wrong so you dont need spares

anyone got a picture?

So it looks like the main retailers don’t have calipers in stock anymore and I’m guessing the newer calipers won’t work with my leavers?
Are the newer xt’s going to have the same issues? Basic hope m4’s look to be about the same money – am I better with those??

Of course you are- spares are available

Are the newer xt’s going to have the same issues? Basic hope m4’s look to be about the same money – am I better with those??

Depends, the hopes are about £240, the XT’s are £120 on Rose Bikes. Hope are good, and it’s nice knowing that they’ll be serviceable, but are they twice as good as XT’s which might last 5 years anyway, at which point you could swap to the latest and greatest brakes for no cost with the other £120 you saved initialy.

My XT785 front calliper piston seals failed after 4 months (moderate) use …replaced under warranty promptly as no parts available. Confidence dented in reliability but still an awesome brake! Credit to Madison the shimano distributer for a rapid sort…they sent a replacement immediately to my LBS before receiving the faulty one.