I clean with soap and water or mineral spirits and a brush. Dry. Then I use something called EvapoRust. Make sure the whole part is in the Evaporust bath. Soak for a couple of hours, and a tootbrush will knock off any remaining detritus.
Another approach is to immerse the part (or frame) in a bath of washing soda (sodium carbonate) and hooking up an electrode to one lead of a battery charger and the part to the other. Google electrolytic rust removal.