[buildyourown]

Im posting this here because people here actually work on their bikes.
On the m985 with the one piece caliper, there is a big cap that must be removed to get the pistons out. Has anybody found a tool to do this? It looks like a huge torx but its not.
I have a leaky piston and Im trying to fix it vs throwing $100 at a whole new caliper like Shimano wants me to do.

 

[HAB]

Buildyourown?

 

[jonKranked]

i'm sure you could find something at harbor freight

 

[Udi]

The generally accepted trick to deal with this problem is to hold the piston that is closest to the hose's entry point and use the lever to pump out the other piston until it falls out completely. At this point you remove the hose, sit a conical nosed air compressor fitting against the threaded entry with some rubber if needed, and blow out the remaining piston.

The piston "cap" on most monoblock brakes is there to allow machining of the bores in the first place, rather than as a service hatch, so the cap isn't really intended to be removed. It's pretty easy to get the pistons out with air if you are methodical about it.