Lost all function in the rear XT brake over the last two days. Now it will bite eventually if I pump long enough but less than satisfactory. When I squeeze the lever and watch the caliper I can see bubbles/fluid coming out so I'm guessing a seal has gone.

Question is can I buy the bits to replace the damaged bits or should I spend 29.99 on an XTR caliper from CRC (assuming that'll work with the levers)?

OK, two questions then. Any answers?
Doh, three questions.

Where on the caliper is the fluid coming from?Only certain spares are available from shimano, so repair may not be possible.

How new is it? How long is the shimano warranty? If a seals gone then surely your shop should be able to get it repaired on warranty, ie free of charge?

Second hand bike but it's possibly 2 years old.

I haven't taken it apart but the fluid seemed to be coming from around the piston. TBH I'm just imagining how it's all put together never having mucked about with mtb brakes, just cars and motorbikes, but I assume there is some kind of flexible seal around the piston which has gone/is going.

I'll ask in a shop tomorrow I think but I'm tempted to just buy the £30 new xtr and be done with it.

who needs brakes?… 8)

… they only slow you down

you cannot repair the caliper there are no serviceable parts on it. Bin it and buy a new one. Unfortunatelly you are not the first person to be afflicted with this problem.

Thanks hustler, that's the kind of definite advice I needed!

XTR caliper will work fine with XT everything else?

Should do, but email the guys at crc to check, or pop another post up here.