I normally clean every four races. I completely disassemble and soak everything but plates and discs in brake cleaner. For plates, I use sandpaper and scotchbrite pad. For disks, I use a brass wire brush. Then I reassemble and grease the bearing.
smc recommends a "prater " brush on the disc (small wire brush) and always assemble disc, floater and clutch in the same orientation , meaning mark everything and put it back the same clocking that u took apart......smc explains it all on there website