has anybody used foam to fill the frame to prevent water and rust?
as everybody knows the old toyotas are notorrious for rusting, i have allready boxed the frame and sprayed it with undercoating but now i was wondering if anybody has filled the inside of the frame with foam to prevent rust?

opinions, pro's, con's?

I would think it would just hold water....................

those foams will tend to soak up some water and hold it ther where it will do the most damage. I'd advise against it. Just keep undercoating it and washing it out when you get back from a trip. Put the front or rear of the frame higher by driving up on something so the water will run out.

You will need to use closed cell marine grade foam or it will soak up water and rot out the frame 10x faster! But it will still trap water between the frame and foam and the rust will take off since it will never dry.

All I do is open the drain holes up on the bottom of the fram to 3/4 and then weld a washer around them. But you have to be religious about rinsing the frame out after every wheeling trip. Hope this helps

ok thanks for the help guys.

Aside from that, if you ever need to weld something onto your frame, it's now filled with foam that I'm sure is flamable.

Hans

HsOffRoad, that foam stuff isn't flamable, if you hold a lighter under it for a while. but besides that an exhaust pipe's heat couldn't set it off..it would need a direct frame, not excess heat...ass for water absorbanyc, i'm not sure..i am using some cheap foam in a can to fill in some gaps in my paneling, before i bondo it, since some holes are too big..its a hassle to do though...what you could try is get a sheet of metal, like the frame on your rig, and then fill it with foam, and bolt it to your frame..do your normal washup, and keep that frame piece under there for a few wheeling trips and see if it generates more rust. if the rust is the same, cut the tube open and feel the foam, and maybe cut it apart to see how wet it is

we filled a unibody with foam the one time to make it stronger and to try and stop rust, doesnt help, still make rust holes and im sure it happend faster then without the foam, it just isnt a good idea, and if you use rubberized undercoating make sure there is NO rust or you will also trap in moisture and cause rust, only use rubber undercoating on new metals. best way to stop frame rust is 5 coats of primer and 3 coats of paint, check it every 2 years for touch ups

There is a foam I used for my waterfall that prevents water from going behind the rocks, but you would have to completely seal the frame and at that point.....