Minor floor rust repair

JHZR2

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No harm in testing the waters with a wire brush. I would say tread lightly. I've opened Pandora's Box a few times with a scraper and wire brush, and ended up with a project I didn't plan for. Having said that I learned a few tricks along the way. It's nice starting out on a low stress project were an OK job is perfect.
Yeah, the good news Is the end result of this is entirely hidden!
 
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It's probably better to do entry level body work with rivets or self-tapping screws than welding right off the bat. You still will get the aggravation joy of shaping your new metal and cutting the old rust back.

So do the POR15 then do something to keep water out of the gaps where your metal sandwiches together. Bondo attracts water. Silicone caulk is not as chemically great as "real" seam sealer. 3M must make something nice. Then when you're all done, blast the underside with undercoating from a can.

Flux wire welding doesn't really work well below exhaust pipe sizing, ~17 gauge, especially for beginners. MIG is your best ticket to "tin work". It does the thinnest body metal. That said if you find a nice name brand machine like a Hobart Handler on the used market, you can use it and sell it for about what you paid for it. Just have to get gas.
 
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Eljefino brings up a good point. If you don't have gas on your mig, is hard to do thinner metal.

I still think if you can weld a patch underneath, or rivet in a long patch over it , from good metal to good metal, you can just brush out the rust chunks and pour in some por 15 to fill the tray you just made.

The problem is, once you start, if you can't find good metal, you might have to go to a shop. There is always more rust than meets the eye.
 
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It's probably better to do entry level body work with rivets or self-tapping screws than welding right off the bat. You still will get the aggravation joy of shaping your new metal and cutting the old rust back.

So do the POR15 then do something to keep water out of the gaps where your metal sandwiches together. Bondo attracts water. Silicone caulk is not as chemically great as "real" seam sealer. 3M must make something nice. Then when you're all done, blast the underside with undercoating from a can.

Flux wire welding doesn't really work well below exhaust pipe sizing, ~17 gauge, especially for beginners. MIG is your best ticket to "tin work". It does the thinnest body metal. That said if you find a nice name brand machine like a Hobart Handler on the used market, you can use it and sell it for about what you paid for it. Just have to get gas.
3M does make a good brushable seam sealer, p/n 08656, in a blue can. I have had good luck with it.
 
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Wirewheel. The ones which fit on drills, are nice, when one cannot turn the tool around. Just put it in reverse and one can get off much more rust.

Ospho on a Sponge scrubbie. The 99 cent store ones are good enough, but scotchbrite is best, scrub until all metal and nearby paint has only slight amounts of rust color, wipe it up, and dab pm a final coat of green ospho, and walk away.

Ansell 88-394 AlphaTec gloves, or similar 20mil+ thick gloves, can handle such abuse.

When the Ospho soaked rust turns black, one can take a sharp cheap chisel, and lift up the bigger rust bubbles and where the rust had gotten under the nearby paint.

Chiselled Rust bubbles will be brown, Apply more Ospho, and scrub some more.
This can be repeated until there is just pitted etched steel, if one wants to take it that far.

Once Ospho is left on long enough to leave some white flaky residue( usually 12+ hours) , brush it off, then wipe with acetone on a rag until rag does not change color..

This Ospho'd surface will bond well with anything applied atop, bond very well, but mechanical tooth can further increase subsequent bonding by a large degree. Think sharp sandpaper in an X pattern, or even using a razor knife to scratch gouges into the steel Or even tiny shallow holes drilled at opposing angles.

I use epoxy, designed for saturating fiberglass. It has the viscosity of warm to hot honey. I apply a thick coat, then lay a prewetted portion of epoxy saturated fiberglass tape, or several layers depending on strength desired.

Epoxy has MUCH higher adhesion than commonly used/ easily available polyester 'fiberglass' resin, and is much more impervious to moisture/ oxygen intrusion than many layers of properly applied quality paint. One can apply a thick coat and have it cure to a thick stink free encapsulating film, in 4 hours depending on the exact epoxy and temperature

Epoxy is also more flexible and can expand and contract far better than polyester resin with temperature.

We've all see hideous fiberglassing, where polyester resin was used on a poorly prepped greasy painted rusty surface, to which it never bonded or bonded so poorly it popped off the first time the floor nearby was flexed with a heavy foot.
That, is not comparable to using Epoxy on properly prepped etched steel, especially when one adds significant mechanical tooth.

Epoxy, if it is to see UV light, needs to be painted.

Epoxy needs to be mixed to the prescribed ratios as exactly as possible. Do not adjust these ratios if it is a hot or cold day, as one would with Bondo or 'fiberglass resin'.
The fiberglass laminating epoxy that I use, has a 2:1 ratio by volume, or 100:45 by weight.

I use a digital scale as the graduations on many mixing cups can be way off, and if one misses by more than 2 to 3% then the cured product has some fraction of the strength, hardness, and adhesion strength as it would have, had it been mixed precisely.

My mixing stick is flat, the bottom edge fits the corner of the cup, and all 5 square sides get scraped on the same exact spot on the rim of the cup. This insures faster complete mixing of parts A and B.
The epoxy must be thoroughly mixed. Use good light and reading glasses until there are no visible swirlies, then scrape the sides of the mixing stick and cup one more time just to be sure.

If one cannot be bothered to be precise in the ratios of A to B, or can't be bothered to insure Epoxy resin parts A, and Hardener B, are thoroughly mixed, then don't even bother trying.

Paint the precut fiberglass patches, which are on some nice clean crease less cardboard, let the fiberglass soak it in rather than trying to force the resin to the weave.

While it soaks into the fiberglass, go paint the treated prepped steel.
Return to fiberglass and remove excess resin with a bondo squeegee.
Lift prewetted fiberglass patches from cardboard with edge of squeegee and lay in place.

Typically there is a bunch of extra epoxy as one mixes more than they need. There is alsolikely some extra time to apply this extra epoxy on something else, like some wood or something else which needs a strong glue, Good to have it already prepped for this extra

Epoxy slowly gets thicker as it cures, but if left in a large mass in the mixing cup will get hot quick and thicken quickly, and even start smoking if it isa a large mass on a hot day, so once thoroughly mixed, get it out of the cup, or spread it thin.

Epoxy does not bond to plastic baggies. One can lay such plastic over curing epoxy as it thickens and force excess epoxy from the fiberglass to teh edges, and mold it like clay. Push the edges flat, or have a bigger piece of foam rubber and a flat piece of wood and a weight to keep it in place as epoxy cures. If fiberglass turns white under these ministrations, you pressed too hard.

I've tried to chisel off fiberglass applied to steel with the procedure used above, and could not easily pry it off, much easier to sand it off.

I've yet to have any failures, and many are highly stressed areas.

Like most everything the result is all in the prepwork, not just going through the motions, but understanding the reason for those motions.

For example, one can use dull sandpaper and it looks perfectly scratched to teh naked eye, but sharp sandpaper leaves sharp V shaped valleys and Mountaintops, where as dull sandpaper has U shaped and will have a fraction of the surface area to bond to.

When Filleting corners is required, I will add milled glass fibers and some wood flour or other thixotropic agent to the mixed epoxy until it reaches peanut butter type consistency.

Achieving Secondary bonding, when epoxy cures in humid conditions, even with so called 'blush free epoxies' can require washing off the water soluble blush, and sanding some mechanical tooth before attempting to bond anything to it.

It's best to not have to employ secondary bonding, if one does not have to.
Relying on a chemical bond during the initial cure is superior, when possible.

I know that cutting out and welding in a new piece of properly formed steel is the right way to do it, and likely less work than the Epoxy saturated fiberglass method, and all the significant prepwork in volved in achieving a good to excellent bond.

I personally don't have a welder, but do have all these other supplies on Hand, and the skills to use them, properly, effectively, so that's what I do.

My Favorite Epoxies are those made By System3, but they are pricey.
Here's a link to some cheaper stuff I use for metal encapsulation/bonding.

Fiberglass tape can make such tasks easier and cleaner, but sharp scissors are required either way.

Do not use fiberglass matt with epoxy, that material requires the styrenes in polyester or Vinylester resins to dissolve the binders holding it all together.
 

JHZR2

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I removed the seats and checked more both from up top and underneath. Seems very solid past what I had seen, a 6” strip.

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I can access from above and below. I don’t have a MIG welder, only access to a wire flux welder. Wonder if I can sandwich heavier metal top and bottom, weld that, and then seam seal/epoxy it. I don’t think I’m keen on cutting out too much. While I felt and pressed/tapped hard beyond what is shown, and didn’t find anything bubbled or crunchy, I still somewhat fear what I could find, and get in over my head.

The seat bolt locations are solid and look great, the rusty metal shown is also very solid, FWIW. Tried to break some and make a bit larger of a hole, and couldn’t without substantial tools.
 

JHZR2

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It's probably better to do entry level body work with rivets or self-tapping screws than welding right off the bat. You still will get the aggravation joy of shaping your new metal and cutting the old rust back.

So do the POR15 then do something to keep water out of the gaps where your metal sandwiches together. Bondo attracts water. Silicone caulk is not as chemically great as "real" seam sealer. 3M must make something nice. Then when you're all done, blast the underside with undercoating from a can.

Flux wire welding doesn't really work well below exhaust pipe sizing, ~17 gauge, especially for beginners. MIG is your best ticket to "tin work". It does the thinnest body metal. That said if you find a nice name brand machine like a Hobart Handler on the used market, you can use it and sell it for about what you paid for it. Just have to get gas.

Ive been thinking about this for a while.

I can’t see how rivets or screws would give the same strength. There’s nothing really clamping any one item to another, since it’s floor, and the forces are vertical. This isnt a rocker or fender. So having some consistent metal (welded), I would think would be pretty different in terms of strength.

So thst takes me to my next thing - wire flux welder is cheap, and I can borrow one. I can rent mig from a local supply, but it’s a learning curve for either one. Wire flux I can borrow for longer for no $.

If I was to buy, cut and shape 20 or 18 ga or even slightly thicker metal, what difference would it make? That would help avoid the burn through issues Id think. The joints could be overlapped too. Would this be an issue for other reasons?
 
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I would be surprised if the frame is sound with such heavy rust damage present.. Myself, I wouldn't waste the time to repair that sheet metal on a 96. I'd ditch the truck.
 

JTK

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Those pics give me the urge to fluid film or woolwax the inner and out rockers again on my 2019 Ram classic. LOL. They'll get done again some time this summer regardless.

Also makes me happy the oedro winter floor liners I have, have chutes that direct liquid right out the door.
 

JHZR2

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I would be surprised if the frame is sound with such heavy rust damage present.. Myself, I wouldn't waste the time to repair that sheet metal on a 96. I'd ditch the truck.
Well the frame is sound, and I routinely haul heavy loads in it. It drives extremely smooth and runs great. The doors didn’t have vapor barriers for whatever reason, and water would sit in the 6” strip. I can see where there is and isn’t rust.

I may not invest $1000 in a MIG welder setup, but think, I can find a happy medium. When the options are $50k+ trucks, overpriced used ones, or this one that ai actually really like with its bumps and dents, Ill take this one. It runs too great to dump it.
 
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JHZR2

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I spent about three minutes with a stiff wire brush on a die grinder.

Ran it slow, hadn’t suited up with ppe, only safety glasses and face shield.

Got a lot of loose rust off. Will take more effort but it’s pretty solid below the top flake.

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that is the one bad spot.

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There’s less rust, but a little for about 2” under the floor mat, then it’s good paint and solid metal from what I can press, try to crumple, and hit.

Big question is if I try to weld to bright metal, or USF coat with a rustproofing epoxy and leave it. I can fill the holes with POR patch or something else.

I’ll probably suit up, going more/harder, then hit the metal with ospho.

PPE is key!
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the patch panels aren't terribly expensive if you can find solid Metal not too far away...
 
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Looking at this I can only see one or two long lasting methods of repair, both require cutting the rot out. You can either weld the replacement panel(s) in or bond it.
Bonding has some great advantages over welding, I have been using this method more and more with stellar results, yes it is strong when done properly but more importantly it is a rust proof seam where welding is a real issue and requires using epoxy or a waterproof filler like tiger hair to seal the weld from moisture.

Use a small body saw to cut it out, wheels make a lot of dust that are not good for the lungs and you don't want the crap in the interior or under the dash where it could foul electrics.
Tar pads on the floor can be warmed up and easily removed with an inexpensive pneumatic scraper. You must have clean shiny solid metal to either weld or bond to.
Post which way you think you want to go and we can get deeper into it.



These parts from the site earlyre linked to has pieces that will work well and are cheap enough.

 

JHZR2

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@Trav thanks very much! I’m confident that I can get to clean bright metal. The need for actual replacement is actually only about 6” wide and 24-30” long. It’s small and flat enough that I have to wonder if it’s actually even worth trying to buy a floor pan versus just some sheet steel, maybe even galvanized if not being welded.

It’s pretty clear to me what happens. The metal is solid outside of this strip, and this is where water that would come in because of no vapor barrier, as well as salt from feet dripping on the rubber mat caused an ideal environment for corrosion from the inside out. The noise cancellation mat under the rubber mat holds moisture too (though it’s ok further inboard).

The big issue is the riser that holds the door seal. I wouldn’t want to cut outboard into the rocker, and I’d hate to remove the vertical part where there’s no rust. I’d hopefully get to bright metal inboard of that, bond a strip of heavy metal, and since I wouldn’t have gone into the rocker, seal it from the underside as well.

This isn’t a big repair and pics don’t do a lot of justice.

Welding isn’t worth it if another approach can be done that avoids some of the sparks, splatter, etc. I watched the SEM dual mix panel bonding DIY and it looks pretty ideal for this. I can brush it all over to ensure a good epoxy bond on all exposed bright metal.

This isn’t a show truck, I’m trying to drive it 60k miles to get to 500k then move on, I think.

Thanks!!
 
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