The seals are the same on all calipers, the M16P used metric bolts for
attachment and metric hose fittings. I am not sure about the bolts on the
caliper
halves. The pistons are a very close fit in the caliper body (probably .001" or
less) but should move freely when lubricated with brake fluid. If the new
pistons were black, I presume it is a black oxide coating over steel to help
prevent rust and make the surface more "slippery." I would have preferred the
stainless steel pistons as they will never rust. Good question about what
actually
retracts the pistons . My guess is that the return spring in the master
cylinder provides a slight vacuum when the pedal is released and retracts the
pistons thus relieving the pressure on the pads.
Berry Price
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