rust bonding bondo

i was under the heep today insatlling an sye and noticed two small rust patches.about the size of the tip of your thumb.now i dont think this constitutes full replacement of the floor pans but i goy to do something. i plaaned on pulling the carpet anyway and herculing it.i know theres a product out there that bond to rust and is almost as hard as steel(which is stronger than the unibody).i've seen it used on a couple old classics that were being restored but cant remamber the name. anybody ?

POR15

POR 15 is a paint, and will not stop rust. POR 15 is mearly a rust preventer and seals the metal from moisture. the best fix is to cut the little rusted portion out and but weld a small piece of sheet metal in there or cut a piece a little larger than the hole and use silicone and pop rivets to hold it there. as for bondo... i am very against using it to cover up rust. if the rust goes untreated, it will only get worse. i have never heard or seen any bondo that can go over rust or that turns as hard as metal. (bondo is a plastic polymer that will chip off with flexing and direct force and is merely a FILLER not a patcher). in rust work, do it right the first time, because the second time will piss you off even more.

rehab said:

POR 15 is a paint, and will not stop rust. POR 15 is mearly a rust preventer and seals the metal from moisture. the best fix is to cut the little rusted portion out and but weld a small piece of sheet metal in there or cut a piece a little larger than the hole and use silicone and pop rivets to hold it there.

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Rehab is right, and even using pop rivets and silicone wont work nearly as well and cutting and welding the rust spots, and then painting over it with new undercoat, herculiner, por 15, yada yada

I've heard of the product your talking about i think, but i cant remember the name. It doesnt seem like a reliable alternative to welding new metal in, or completely cutting out the rust.

I've worked with bondo quite a bit and had mixed results but I wouldn't go so far as to say that it's a total waste of time in all cases. I think the most important thing to work towards is making sure that all metal surfaces are completely free of rust before you start applying the filler. If you can do that then you'll probably be successful.

As far as the rust spots that are as big as your thumb I'd grind all the rust out and then give it a coat of rust converter (the stuff that turns rock hard and black). If it's really deep you can go with some filler. I've done small jobs like this a hundred times and in a hundred different places under my Jeep and I've been happy with the results.

if its really just the size of your thumb and you want an easy simple patch grind down and apply some naval jelly to the afflicated area to eat away at the rust chemically. Then you need to neutralize the rust.

You could get away with a epoxy metal patch (kinda like jb weld?) but it is more the consistency of playdough or clay. It dires hard in about 15 minutes and starts getting "difficult" in about 3 minutes. You have to mix the two compounds together need and twist and bend and kneed very quickly untilll its all one color. Apply a patch about twice the size of the whole on the top surface, and twice the size on the bottom and make sure the two are smooshed together. Also wire wheel the area to give it some surface area to adhere to.

I did this with some holes in my cargo van in 2003 (put in new steel shelfing, the old holes didnt match up) and its held up great. Then when you learn to weld or have more time or feel the need you can simply drill out the patch or chizel it out sideways with a wood chizel, its as hard as steel. ROCK SOLID.

One product is called PC7 and there is a few others ... all available on the adhesive isle at home depot or lowes. Comes in tubes about as fat as a shower curtain rod, or in a clear plastic with two plastic wraped "clays". eace: Costs maybe $5-7

edit: same idea as this POR15 product http://www.por15.com/s.nl/it.A/id.1403/.f

Cut out the rust, clean the area, WELD in a patch, prime ( does not have to be top coated) with something like Zero Rust, works like POR-15 but does not contain isocyanates or lead which are terrible for your lungs. I've used ZR many times with great results.
I think the the stuff you are thinking about that hardens the the rust would be a rust encapsulater/converter but once again most of these contain isocyanates, although Interstate Products produces one that does not have isocyanates but is still considered a potential carcinogen.
Work safe, your lungs have to last you a lifetime, the Jeep won't.

i just did my floors and theres a good chance that when you get that carpet up and tap away at it , that thumb sized hole it will get to be about as big as your first. the ONLY way i feel this should be fixed is by cutting out the area and plug weld in some pieces of 16ga to 18ga sheet metal(depending if bends are needed)

as said before bondo is to fix minor inpefections in sheet metal. in no way should bondo be used to fix rust. you can bondo the outer lips of your patches to make them look smooth and unnoticable but metal must be used and welded in.