Boxed Frame Inside Rust Removal
 

I figured a way to restore these boxed frames. First step is taking the rust off with a screw driver and a long peace of metal and scrape the inside of the frame for 2 weeks striaght. Then after that you take a cleaning solution and a rag and rub that over and over for another inside the frame for another 2 weeks until your hands are bleeding from all the rubbing and sweating. Finally after your done doing the best you can and have taken off 90% of the rust paint the inside of the frame with that internal frame paint stuff that has that special hose. I dont know how long it will take for that 10% rust to start bubbling through but it shouldnt take very long.

OR YOU CAN DO THIS THE VERY EASY WAY.
Plug all the holes in the frame and make it so it holds water from right behind the front tire to say right at the top of were the frame has that curve just infront off the rear tire. Plug ever hole.

You might want to jack up the front end a bit to get the water that high in that area.

Next the ratio. 1 table spoon of baking soda or washing powder per 1 gallon water. I hurd washing powder works better. Either helps conduct electicity. you will probably half to use alot more then 1 gallon this is just the ratio.

You also need to make and electrode with rubber feet that will sit inside the frame submerged in the electrolite solution without acutally touching the frame. This electrode will be hooked to the positive side of the battery charger. The Negative side of the battery charger will be attached to the shiny peace of frame you cleaned.

I would do one frame rail at a time. Turn your battery charger on 2/15amps 12volts and go drink a 12 case of Molson Canadian. Come back say 48 - 60 hours or more ( longer is better ) unplug the batter charger. Unplug the holes you pluged to hold the solution inside the frame.

Take off all inspection plates. Pressure wash the inside of the frame. There will be absolutly not a single spec of rust werever the solution was sitting.

Proceed with letting it dry and paint with por 15 or that internal frame coating. Should last forever.:smokin:

I think i would try this method if i am going to go thru the effort, but you definitely have an interesting idea.
http://www.antique-engines.com/trailer-electrolysis.htm