What's the best way to clean up this rust? (pics)

I would soak them in a can/jar of Ospho (Phosphoric acid). You can get it at Lowe's or home depot. It's by the mineral spirits and paint thinner. Those gears will look as good as new after a few hours!!!



Just don't drop any on your concrete floor. It'll etch it and turn it a lighter shade of gray (if you even care).

http://www.homedepot.com/buy/klean-...ric-prep-and-etch-gkpa30220.html#.UNDvEoYVNMQ