No matter what the cause, structural rust repairs should be one of the first steps of your restoration or build. Rust, especially in the frame and floor areas of the car, is not only unsightly, but can also be a safety hazard when driving your car. Remember that most Mopars, our Barracuda included, don't have a frame per se, so the frame sections, along with the floors, roof, and firewall, form the structure of these cars. This type of construction is a unit-body, or commonly called "unibody" construction and requires that the floors be intact to give the car its rigidity and structure. Having solid floors and framerails is even more important if you're going to install a high-horsepower engine as we are in our bracket race car. Much of the force of the car's rearend is transferred forward through the leaf springs and framerails to the floors of the car. Rusted or missing floors can cause all kinds of problems, up to and including actually twisting the car and causing permanently damaged framerails and rocker panels. Fortunately, new sheetmetal is available to repair most floor damage, and the repairs aren't technically complex. Our Barracuda needed both front floor panels, as well as the passenger side rear panel. We also needed to repair damage in the under-seat area of the passenger side of our car, but no pre-stamped panels were available, so we fabricated patch panels out of sheetmetal. While this sounds like a big job, it's really not all that hard. If you have a welder, grinder, drill, a metal saw, and even marginal technical skills, you should be able to handle it.
The first step to rust repair is to evaluate your car and then find out what panels are available to repair it. Being able to purchase prestamped panels for the repairs is definitely more cost effective than fabricating them out of sheetmetal, which can be very labor intensive. Our car needed both front floors, as well as one rear floorpan. The other rear pan was questionable, so we decided to get it in case we opted to replace it. A quick check of the Paddock catalog verified that all our sheetmetal was available, so we called them up and placed our order. One nice thing about floor repairs is that the parts are relatively inexpensive. By ordering our parts through the Paddock and performing the labor ourselves, we had our floors in great shape for a little over 300 bucks. parts for each model are priced differently, so be sure to check the Paddock's catalog or web site (paddockparts.com) for current pricing on parts for your vehicle. our parts arrived quickly, so we were ready to get to work.
Replacing floorpans is really almost as simple as just cutting the old floor out, fitting the new panel, and welding it in. There are some tools you'll need and some preparation you'll need to do before beginning the job. First, the car should be placed on four jackstands under the front and rear framerails and leveled. We used a carpenter's level on the rockers in the door opening and on the cowl below the windshield, and shimmed our jackstands with sheetmetal to get our car level. Leveling the car ensures the car doesn't flex or move when you cut the old floors out, and stays true as the new panels are welded in. Next, you must determine how much of the original floor needs to be removed due to rust. We try to remove as little of the original panel as possible, leaving as much of the factory's steel in place (very little could be saved in our case) for structural integrity. Use tape or a Sharpie to mark the floor where it needs to be cut out, and use a plasma cutter, saws-all, or jigsaw with a metal blade to cut the floor out. A die grinder with a cutting wheel may be necessary to get to places the saw can't reach, and if the floor needs to be removed from its edge or over frame sections, you'll need a spot weld cutter to remove the factory spot welds.
 We used a jigsaw with a metal...  We used a jigsaw with a metal blade to remove what was left of our front floorboards. Here, we mark the car's floor with a Sharpie, using the new floorpan as a guide. We can then cut just inside the line so the new panel overlaps the original floor slightly. |
 We had some apparent surface...  We had some apparent surface rust around the edges of our floor repair and used a grinder to ensure this rust was confined to the surface and not rusted through. |
 Our front floors had rusted...  Our front floors had rusted away from the framerails, but the spot welds remained. These had to be removed so the new floor would fit flush and could be welded to the existing framerails. A quality spot weld cutter makes removing the factory spot welds much easier. We got our kit from Blair tools. |
 With our rusted floors cut...  With our rusted floors cut out, we begin fitting the new floorpans. Rather than replacing the whole panel, we leave as much of the original floor as is salvageable and weld the new panel to it. This is trial and error; take the time to fit the panels properly. |