Porous metal

Have cab with porous inner door panels. Mixed opinions whether to repair or replace. Most say repair. What is best method?

I really can't see enough there to be able to give much advice. I can't tell if the bottom edge of the porous panel is flat or is molded over the arch. I can see holes in the vertical panel way over to the left, but I can't tell how thin it is three inches to the right of the holes. I don't know what you are working on so I don't what the availability of patch panels is. You have to weigh which way is going to take the most inches of weld and thus take more time.

Found patch panels, but been told easier to repair existing.

Since there is already a couple rusted through places I don't think that would withstand cleaning the rust off to repair it. I think I would replace it if at all possible.

(quoted from post at 08:09:17 03/15/23) Mixed opinions whether to repair or replace. Most say repair. What is best method?

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What door panels? Looks like the backside of a unfamiliar cab.
If it's a beater repair it. If you try to sell it to me, replace every panel.

Is a tractor cab from 1939. Inner panels for roll up windows. Panels do not exist as with most all parts.

The part at the bottom which is so bad I don't think it would be difficult to fabricate.

Not easy to fabricate as has wide band around botton axle hump. Also top edge is part of panel for window panel.

if you want it to last and be done right, find a hot rod shop near you that does metal fab. they can make the panels you need. a little spendy but done right. if you have have a heat and ac guy, they may be able to fab sheet metal for you

All I can see is what is in the picture. Maybe if just the sheetmetal was cut out and replaced. You could use maybe 12 gauge or thicker metal to make it easier to weld.

I have done this with good results on older cars. We aren't talking concours classic cars here, but you can produce good results.

On the less visible side I grit blast (looks like both sides need blasting here), apply a rust converter and back it up with 5 layers of 10 oz fiberglass. With enough fiberglass, you can glass a pretty lacy sheet of metal and make a structural repair where the metal is little more than a form in places. I have used grit blast, a rust converter and polyester resin on a rusted out car floor that stood up to several years of Boston area road salt with no ill effect. I would also consider a zinc phosphate coating instead of the rust converter. I would pay special attention what looks like welds along the bottom to make sure not to encapsulate any crud filled voids. The exact cloth weight is not important as long as the total weight of the layers adds up to more than 40 and there are several layers.

Showcrop's milkstone remover might be a reasonable alternative to zinc phosphate. I prefer the somewhat added protection afforded by the zinc phos, over iron phos, but If I had either one on hand, I wouldn't be in any hurry to buy the other.

I used this on a car floor repair, It was translucent but transparent enough to see that it was not rusting under the glass. The floor was not a cosmetic repair, but since it takes some pretty serious blasting from water and slush, it does demonstrate the durability. Without adequate surface prep, another car floor gradually peeled off the glass, but that old beater just needed to hold the front seat in place and keep the water out until I junked it.

The good side will need some filler in most cases. I prefer to make my own thickened resin for filler since I already have to buy the liquid for the glass. Mixing is dead simple. Add filler and stir until it spreads easily without slumping.

On more visible areas you have to be more careful to support the glass in the more open areas, by using something to back up the visible side to keep it flat. No reason not to apply a layer of thickened resin as a base coat to make it easier to finish the good side.

The suppliers in the links have been reliable over the years. Epoxy resin is better in some respects, but more expensive and not all that much better. It will adhere better to non-metallic surfaces including fully cured polyester and glass.

Once you have reinforced the area, prime and paint as you would metal. The hot rod shop is ideal, but $100 per hour vs $100 in materials, is a consideration.

This post was edited by Dave G9N on 03/18/2023 at 11:32 am.