reconstructive surgery- rust repair

[CathodeRayTube]

Ok iv cut out all of the rotten parts of the first section im planning to tackle...and iv welded in my first plate...but id like some advice on how to prevent further rust after i get everything welded back together and rebuilt...and get some feedback/advice on my shitty welding skills...should i attempt to coat the inside of the rocker panels with navel jelly or one of the "rust stopper" products from walmart or napa...or would spraying wd-40 or used motor oil inside everything be enought? it may look rought..but i was planning to cover everything up to the bottom of the door with roll-on truck bed liner or somthing similar anyway..should i use bondo anywhere also?

[gatemaster]

The best thing to use in that area is Por 15.

http://www.por15.com/

[takza]

Usually I think they hammer the weld area down some to allow room for bondo (before welding)...or maybe the right way is to grind the weld down smooth? You do want to weld ALL edges though.

I've been using fiberglass resin as a paint to rust proof.

My car had some kind of rust proofing...but I used the plugged holes as a place to squirt in used ATF each fall. You'll notice that a lot of the rust is down at the bottom...which is where a lot of the oil ends up...but I do spray it as high as I can and let it run down. Over several years in the rust belt as driven in winter...major rust has been stopped. In the bottom of all doors/hatch..rockers...channels underneath...rear bumper...etc.

[gatemaster]

do it the right way, use por 15, it is what the professionals use. i've used it and it works better than anything else including spraying oil.
Spray on truck bed liner is a great method of protecting rocker panels from chipping paint.

another method besides welding is to fill the area with that spray foam that expands and dries solid. then cover with wire mesh and fiberglass over. Then use the spray on bed liner. Of course the area should be painted with por 15 first before using the foam spray filler, which can be found at any home depot type store.

[CathodeRayTube]

another method besides welding is to fill the area with that spray foam that expands and dries solid.

I thought about that, filling the whole rocker panel cavity with Great Stuff (im assuming this is the thing your talking about...im very familiar with it as its all over our house)..but i pictured water getting in between the foam and the metal and rusting it out faster..IDK if thats good reasoning or not..

and about the POR 15 stuff...can that be sprayed in? i should clarify that im worrying about protecting the INSIDE of the rocker panel cavetys...so it wont rust from the inside out like it did once i guess...theres not much acess to this area other than the small vent/screw holes in the bodywork ..and of corce the holes iv cut out to replace rotted metal...por15 sounds like a great idea for the OUTSIDE surfaces...or am i missing somthing?

or maybe the right way is to grind the weld down smooth? You do want to weld ALL edges though.

i did manage to grind down the welds so there pretty smooth and flush with the rest of the surface...but theres lots of little pinholes and spaces because my welding sucks...partly the welder itself..(cheap-O gassless wire welder from harbor freight) and my poor skills i guess..there strong welds and hold fine when i kick it or beat it with a hammer...there just not pretty..

[gatemaster]

the por 15 is for the inside. It can be sprayed with a sprayer. Then the foam and wire. It can be used on the outside but needs to be covered with other paint as it is sensitive to the sun. It becomes hard like powder coat and bonds to the rust stopping it. Customizers sand blast the frame then coat it with por 15 and a top coat. It prevents rust better than anything.
The web site has all the information

[splatterdog]

Por15 is very heavy duty. Rust Bullet is a similar product that isn't supposed to be UV reactive. I've used both with good results. Can't remember which one I used on the 84's windshield frame. But, I wasn't happy with the topcoat and was ready to start over so I removed it with a wire wheel/drill. Amazingly this mostly just shined the basecoat as the topcoat easily went away.

Just get it right the first time and thoroughly clean anything you want to keep for next time. That stuff is like superpoxy when it's cured.

[takza]

The problem with foam/wire is that isn't structural...which is needed because the rocker panel is part of the frame. If you are welding...any kind of paint is going to mess up the welds...and the welds will mess up the paint? Then you have a place for rust to start.

What's cool about oil is that it creeps into small places...can be redone...and doesn't trap water. Because it's low tech...people don't like it. I could do the oil every other year...but I go ahead and get under it each year and look for new rust spots...also now use spray white grease on surface spots underneath that start other than in the wheel wells....there roof cement over the alum/plastic roof tape.

FB resin costs about 1/2 what Zero-Rust paint does.

This is stuff I've found that works...I'm too cheap for POR 15.

I've been thinking...and thinking...about that cheap HFwelder. I wouldn't worry too much about sloppy welds...just that they were strong. Welding is hard to do right....espec sheet metal.

[CathodeRayTube]

por 15 seems awfully expensive...but i suppose it is very HQ stuff...however it says on the website that if a bead of sweat drips in the can its ruined and should be thrown away...holy crap...i would cry..or shoot somebody.. if that happened after dropping $150 on a gallon can...i may still go for it but IDK...

i think im going to go with rustoleum primer for the insides of the rocker panels...then pump the whole rocker panel cavity full of Great Stuff (foam) after i get all the metal panels replaced...does that sound like a good idea? actually going and welding in new metal AND then filling the whole thing with foam also as an extra meashure...or do you guys think the foam will trap water and make it rust out again...

and then i was going to do roll on bedliner on all the exposed parts of the underside...i planned to sand/remove all the old undercoating and take everything to bare metal before applying said bedliner...my question is should i paint everything with either por15 or rustoleum before applying the bedliner? or will the bedliner over bare metal be enought...i also planned to put roof tar in the wheel wells and other difficult spots too..

[ARCHINSTL]

As to the foam - I have a feeling that it will absorb water and may be worse in the long run, in that it might retain the water for a looong period before drying out. I'd suggest doing a Google search using phrases like "foam for body repair" or similar.
I'd also contact the foam manufacturer (better luck by telephone, I'd wager); I'm sure you are not the first person to wonder about this application of the product.
Tom M.

[cannondale]

I have used the spray foam to fill a hole in the rocker panel and wondered about it retaining water . I noticed it seemed to repel water quite well only if it was left as is( not cut, which you have to do to shape it). Once it's cut and some of the inside is exposed it absorbs ands holds water like a sponge. I put a very thin water proof tape over the foam and sprayed my entire rocker panels with the rubberized bed liner stuff. Hopefully this holds up.