Rusty!

To get rid of the shitload of rust, we checked the internet. 
Easiest and best way to do it is using Electrolysis.
Just put the rusty part in a bath of water, mixed with soda. Put in a second piece of iron. Attach a powersupply (we used 12V/2A). Minus to the rusty part, plus to the iron.
This was just a test, but it did the job very well. This is what we'll use (in a bigger box), to take care of the rest.