scored and pitted caliper pistons - how much is too much?

[oldgreyandslow]

I've removed the caliper pistons and cleaned them, after a liberal dose of brake cleaner, 600 then 1200 wet and dry and fine wire wool 5 have come up OK, 3 however have a bit of light scoring and some very slight pitting still there. The pitting on one is right at the top, the others about 1/3 down.

Can I get away with using these, is there anything eslse I can try to get the marks out or do I need new pistons?

While the calipers are off I'm going to be painting them, masking the fixings and bores looks like it'll be a challenge!

Cheers

[Chrissy_J]

There's a way of filling pits in fork sliders, that involves filling them with epoxy adhesive and using an oilstone to smooth it flush with the good metal... don't know if that would be any use here, though.

I think ... you'll probably be OK with them; if you're, ahem, generous with the red rubber grease on assembly, it'll fill any pitting and so help look after your new seals.

Depending on how bad you think they are, and how many you have, it might be worth replacing them with new ones- look on eBay for 'x brake pistons' where x is the diameter in mm. That's what I did with the rear pistons on my NC21.

As for repainting the calipers, I used pieces of 'J cloth' (the blue cleaning cloths you can get at the supermarket) stuffed into the bores, and old banjo bolts and bleed nipples screwed into the necessary places. You can thread a piece of wire through the banjo bolt and hang the caliper up for spraying, which is a bonus... Any overspray in the piston bores can be scraped out with a sharp knife blade or a Scotchbrite pad, which is what I did.

Pics when you've done them, yes?

[V4beermonster]

go to local machine shop can get them made from stainless cheaply