07-06-20, 09:47 AM
(07-06-20, 08:19 AM)Dudeofrude link Wrote: You can get this off with a piece of wet and dry. All 8 of mine had a pretty thick line around the rim but managed to get them all back to almost new.
I used a bit of 1500 wet & dry then polished them up after with some metal polish and a soft cloth to make sure they were nice a smooth
Tedious work but worth it
The pistons are nickle cadmium coated, where there's pitting/corrosion the coating has been damaged, the corrosion will spread no matter what you do. Any pitting/corrosion lower than 6/7mm from the edge will render the piston unserviceable, any pitting/corrosion that sits below the dust seal when the piston is retracted will start recorroding and cut the seal/s. This can happen within weeks of you servicing them and they'll be sticking eventually seizing.
This is another factor you should consider when using non OE pistons. The coating is microns thick, AM pistons are cheaper because the coating is thinner and softer, I've seen these AM pistons corrode just sitting in air! If you use the bike daily and ride in rain or the odd salt covered road, AM pistons will seize in quick time unless you keep them coated, even that will not stop them corroding.
This is why car brake pistons have rubber boots that cover all but the top few mm.
Later