Knackered piston, I think has caused issues

paulneenan76

I have a Deore m596 on the rear and for many months, particularly on bigger rides, the piston is sticking and causing the brake to drag - killer on long steep climbs.

Have cleaned the piston half a dozen times and it runs free enough until the next big ride. Recently noticed a big chunk has been taken out the piston - probably my fault - and wondered if this is likely to be the cause of it sticking and when warm, dragging?

I have a piston or two from a calliper in the shed - can it be replaced or is it new brake time?

Ta

The Rookie

Of there is a chunk taken out there will be deformation round that that almost certainly sticks out and could cause it to bind.

Shimano callipers are nominally not serviceable.