[Lippyp]

I use a great product for de-rusting stuff called DEOX-C, it comes as a powder that you mix with water, you soak the part in it overnight and it comes out clean, it works even better if you can keep it warm maybe with something like a fishtank heater and take the worst of the loose rust of first with a wire brush. Its non-toxic, non corrosive (you can shove a bare hand in it with no problems) and works really well. After a couple of goes it turns black and is exhausted and has to be chucked away and you just mix up a fresh batch.

This shows a metal shutter from my house in France that we treated with this, Green is after painting, the middle is bare metal and the right is how it looked before it soaked overnight. This was very heavy rust from years of sitting outside with no paint on and it looked like new clean metal. www.bilthamber.co.uk for contact details.