Im getting ready to start replacing the floor pans in my 50 dodge and Ive been wondering what the best gauge sheet metal to replace them with... Ive noticed that repop floor pans are usually out of 16 to 18 gauge but a good friend of mine told me to use 10 or 12.... I know this is a total FNG question but cut me some slack. Thanks guys.
I would use ether 18 or 20 ga. You'll have hard time bending anything thicker. Make sure you use cold roll finish not hot roll. You'll probably have to do some welding. This will helpto give you cleaner welds. You should either bead or step the panels for strength. And lap weld and rossette weld wherever possible. Butt welds will eventually fail!
I think a butt-weld is fine for sheet metal work. I've been welding for over 15 years and have yet to have a sheetmetal butt-weld fail. If you are a newbie at welding, or don't have the expierience at welding thin gauge metal then over lapping the edges and making your weld there would be the best. Just be sure you put beads on both sides of the "laps", as penetration of the parent metal is not as uniform as a butt-weld would be.
I noticed that most cheap bead rollers max out at 18 gauge... Im a newb when it comes to welding so thanks for the tips. I think Ill end up step welding it. I would have liked to use something thicker so I wouldnt risk burning through a thinner gauge.
most old cars were 19ga so if you went 18ga your already thicker than stock. if you dont have access to a bead roller i would say 16ga
I used 16 ga without any beads on my 47 Dodge, I duplicated the factory floor bracing which were about 11 inches apart. make sure they are a flat, tight fit because other wise they will oil can a bit. I had to drill about 5 plug weld and refit/weld them. If your going thinner that 16 I would bead roll it. also If you are going to have a large unbraced area I would also bead roll it. I reference to the butt welds. I have heard that plug weld will alow a little flex, where as if you butt welded a long area like a rocker you have a long brttle (mig) seam that will crack rather than flex. If you look at the factory stuff most just overlapped and spot/plug welded them. It easier, quicker and will put a lot less heat to the panel. heat cause warpage which can also lead to an oil canned floor board.
Factory welds usually are spot or plug because it is cheaper and faster. If you take your time you can make a good stich weld with a mig welder that will last longer that the ride. Since we are not in the business of mass production, I would rather have a good stitch weld on butted panels than a panel held together by a few plug welds.
^This. Beads and bends will add stiffness, so you can use thinner metal compared to a mostly flat sheet with little or no support underneath. I used 16 gage flat sheet for a 24" x 43" trunk floor, but have two u-channel supports 12" apart in the center, and two smaller right angle iron pieces to help support the outer 18" or so. I could have used 18 or maybe even 20 instead, but 16 gage was more easily available locally: If it feels like the metal is too flexible in a certain area as you are replacing it, add a bead or a brace to stiffen it. Really, follow your gut and you'll be able to "feel" what works best for each area. You can always err on the side of caution and go one step thicker if in doubt. If you hear and feel oil-canning, you know you need more stiffness.
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