1 tablespoon of washing soda per gallon of water in a plastic container.
negative pole of battery charger connected to the item you want to clean.
Positive pole connected to a sheet of steel plate (will be eaten away after some time) OR a piece of SS (wont be eaten away, just has to be wiped clean occasionally)
Be sure the clamps of the battery charger are NOT in the electrolyte or they will be eaten away rapidly!
Depending on the amount of rust to be removed, let the process run for a few hours or over night. Don't worry about the item to be eaten away... this wont happen. The process is "self regulating". Once the rust is gone, the current will stop running too! The process leaves a black layer of something. I don't know what this is (carbon maybe?) This layer can be washed off under running water. Be sure to dry and cover the metal with something right after the process. Otherwise it'll rust quickly. All rust will be removed, but no metal.
Rusted tight bolts can be loosened using the same process.