QuestionThanks Bill... If I use aluminum, is there going to be corrosion where it contacts the steel floor?
Would I use aluminum or steel rivets?
Would it help to paint both patch & floor before putting it on?
Perhaps tin would be better?
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The text above is a follow-up to ...
-----Question-----
Hi Bill;
I'm repairing a rust hole in the floor of an '84 Chev G-20 van, behind rear fender. The exhaust is smoking me out. I've removed most rust, wire brushed, treated with rust converter, and primed around the hole. I cut a sheet metal patch with tin snips. I was going to rivet it over the hole, and bondo around the edges. Problem is, the floor is corrigated with gutters running length-wise, and the hole area is partly on 2 ridges & the gutter in between. I tried hammering the patch into the shape of the floor, but it's too hard. How do I shape the Patch? Or should I use something softer like screen, mesh, or tin +bondo? Should the patch go over or under the hole?
Thanks,
Phil
-----Answer-----
It will be impossible for you to match the corrugations in the floor, unless you use incredibly thin metal, like aluminum sheet, or have ready access to a metal brake. Lay a patch on top, rivet it in on as many high spots as possible, then hammer the metal down as close as possible to the low part of the corrugations. Use seam sealer or bondo to fill the gaps. It won't be pretty, but it will stop the exhaust getting in. If in needs to look good, maybe you can have a junk yard cut out a good section of floor, and you can graft it in. I'm pretty sure that the corrugations are uniform, so a piece cut out anywhere will work. There may be aftermarket floor patches or pans available, you will need to contact a local body shop to find aftermarket suppliers in your area. Bill
AnswerYou are correct, the sheet aluminum will cause corrosion if bare aluminum is placed over bare steel. My thinking is ease of installation as opposed to longevity. I have no idea what the van looks like, but here in the rust belt, an 84 G van usually isn't long for this world. Even using tin, hammering and riveting a patch over the hole is a temporary stop gap measure, at best. We in the body field call this cobbling, a nice way to say its been half assed together. If you want it to last more than a year or two, the rust will need cut out, and patches or a floor section welded in. That is the only way to do it right. My impression was that you were mostly concerned about exhaust entering the vehicle, and how to form a patch. I still think that aluminum sheet is better, it won't rust away nearly as fast as metal that's as thin as a thinner can, and its very malleable. Painting before installing will definitely help. Rivets? Go with steel, they will be protruding out the bottom of the van, where moisture will accelerate the electrolysis between aluminum and steel. This is the easiest, cheapest way I know, my friend. It's going to take some coin to do it right. Bill
