How to Rebuild a Brake Caliper: Saturday Mechanic
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. Unlike surface damage to the piston, minor pitting of the bore is no big deal--the square-cut O-ring seals between its recessed groove and the piston, not to the outer bore.
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I am reading about how a caliper works. Is my understanding correct?
First, why is there a seal? If there were no seal, there would have to be perfect clearance b/w the piston and bore. Too little and the piston can't move. Too much and the fluid goes around the piston. Sort of like oil getting past piston rings? So, there is a seal to give some play while sealing the fluid ?
So the parts that need to be in perfect tolerance are the piston and seal, since they are what trap the fluid. The bore itself is never part of the contact area. If there is a pitting in the piston, and fluid will bypass the seal there, and you lose pressure. Right?