Rust remover. I just might give this a try. Perhaps better than naval jelly?
http://www.evapo-rust.com/
EASY TO USE
Evapo-RustŪ removes rust, and it does all of that work for you. No more scrubbing, sanding, sweating, mixing, or babysitting, unlike other rust removal methods. No special tools or ingredients, just soak, rinse, and dry.