Good grief!!! The best, easiest and cheapest way to remove rust from track is with a bench grinder with a wire wheel.
I've cleaned many pieces of track that were dirty and rusted that, for a minute or two were run through the bench grinder wire wheel, came out looking like brand new.
I've saved one model train owner hundreds of dollars in not buying new track.
It is only the top middle rail (for electrical pick up) and the two outside rails (for ground) that need to be "clean". While the track may look crummy, it is the electrical contact with the locomotive pickup rollers (which must be clean) that makes it go.
Yeah, you can dump your dirty track in a container with solvent or whatever, but the best method is using a bench grinder with a wire wheel to remove all of the rust and debris to have raw, clean metal for pickup rollers and wheels tomake your train go without any problems.
Oh, and for rusted drive rods and stuff, get a dremel tool and buy one of those rubber abrasive wheels that will remove the rust and polish in a few seconds and theyll look like new.
CRATEX rubberized abrasive wheels:
They have changed their website since I was there several years ago,
but get the 441-074F abrasive wheel for your Dremel tool.
Scroll down to the number:
It does amazing things in cleaning, brightening and restoring rusted metal.
But you gotta be careful. This abrasive wheel is very effective. So go lightly on anything that you want to remove the rust.
Trust me. It is the quickest, easiest and most effective way of removing rust from your train items. But you do have to be careful when using it with a Dremel tool.