With the old panel out, the new one can be placed on or under it, and marked to be cut to fit. There are a couple of methods here depending on the result you desire. The new panel can be cut to the actual size of the hole and then butt-welded in. The welds can then be ground flush so the repair is nearly invisible. This method works well on restorations where a factory appearance is desired. The method we used is to overlap the new floor over the original slightly, then weld both the top and bottom sides, creating a double weld that holds the new floor in place. This method won't give the factory appearance that butt-welding will, but in our opinion gives a stronger end result and is more appropriate for our racing application.
Once the new floors are welded in they can be treated with rust inhibitor, primed, and painted to prevent them from rusting again. Treating the new, raw metal floors with rust inhibitor is an important step as it chemically makes the metal's surface resist rusting. Priming and painting the metal after treating it should ensure that your new floors last the life of the car if taken care of properly. We used OSPHO to treat our floorpans and then primed them with a quality primer. As our project proceeds, we'll paint the floors when we paint the rollcage and the rest of our interior, which will give our Barracuda better corrosion protection than it had when it left the factory.
 We used an electric jigsaw...  We used an electric jigsaw with a metal cutting blade to trim our new panels to fit. A saws-all or die grinder will also work. A plasma cutter is the easiest method, but we don't have one so we used what was available. |
 With our new panels fitted...  With our new panels fitted and our floors marked, we used a grinder to remove the paint and any surface rust from the area we'll be welding. We'll be using our Lincoln mig welder for this project; to achieve a nice weld the metal must be clean and free from contaminants. |
 Using our Lincoln mig welder,...  Using our Lincoln mig welder, we begin welding our new panels in place. We stitch-weld floorpans just like we would an outer body panel to prevent heat build up from warping our new or existing floorpan. |
 We had rust in several places...  We had rust in several places that wouldn't be covered by our new floorpans, so we had to fabricate patches from sheetmetal using a hammer, blocks of wood, and a vice. This is somewhat time consuming, but is not technically difficult. Remember, measure twice, cut once! |
 As our fabricated panel is...  As our fabricated panel is welded in a hammer can be used to contour it to the existing floorpan. This panel is again stitch-welded to prevent our existing floors from warping. |