definitive word when to toss caliper due to corrosion?
 

Did lots of searches on rebuilding calipers that discuss corrosion or pitting. General consenus seems to be that some corrosion/pitting on both the piston and bore is o.k. If you agree, how much?

Piston: I have some pitting on outermost 1 or 2 mm of the piston. Is this o.k.? Seems that this portion of the piston would never reach the seal to cause a leak.

Bore: My bores are corroded from the seals outward. I would think that as long as this doesn't cause the piston to hang-up it shouldn't matter. Also, how would I hone the bores (in particular the area outside the seal) without splitting the caliper?

Thanks.

As I am rebuilding mine I was wondering the same thing...I lightly rubed my pistons with 2000 grit wet sandpaper, around the pistons. It did not take much to remove the gunk. I would think anything there(that far out on the piston) would just create more friction to overcome when the pedal is released, not cause a leak though. Same with the bores, I just cleaned them up so the pistons will retract smoother. They are in the paint booth right now(guest bathroom) or I would post pics.

Let's get some more thoughts on this one.

Some pics would help.

On my kart brakes I'll bore them out a couple thousandths and put in new seals. With more that a couple thousandths, I'll make new pistons to close up the clearance.

To hone or bore the piston bores you'll need to separate the caliper halves.

If you clean them up some with a hone, etc. -- can you still feel pits when you rub your fingertips on them?

Pretend you're a machinist and feel them - you can feel the thickness of a sheet of paper....

Then you want to think about the cost issues re replacement vs. working on them, and are they rare calipers - are they "S" calipers?