I'd suggest using a rust removing chemical. Vineger, and CLR work, but if you goto a hardware store they should have something stronger. Let it sit in a tub of that stuff for a day or so, then get a scotch brite or something to wipe it off. Should work well. Good luckI bought a used JDM LSD off ebay. It came with surface rust, but the gears are fine. Any suggestions on removal?