Rust repair panels are used as an alternative to bondo on older cars. These panels can be purchased from a variety of places and are made of the same type of metal that a traditional quarter panel is comprised of. This allows drivers to cut out rust and repair it using actual metal instead of a compound. Panel replacement can be tedious work and you will need a variety of tools to complete this repair.
Before you begin you will need to gather your tools and some new repair panels. In order to do this repair you will need access to an angle grinder, sander, metal chisel, fasteners, welding clamps, pliers, a welder, scrapers and media blaster. Rust repair panel kits can be found online or at auto parts supply stores. They are typically made up of several pieces to use as a replacement for your quarter panels. You will need to purchase a kit specific to your vehicle.
Next you will need to take a pen or marker and mark off what portion of the quarter panel you will be removing. You can use the new parts as a guide by pre-cutting them and tracing around them. There is absolutely a maximum length (the length of your new pieces). Typically you will be cutting a long, thin piece of metal from the center of a quarter panel (leaving the top and bottom on) and welding it into place.
When cutting it is important to note that you may be forced to clamp or brace the lower portion of the quarter panel ahead of time to keep it from falling off. Using an angle grinder, carefully cut out the rusted area, making sure you stray from the lines you have previously marked out. Make sure you cut only the outer fender when doing this step. Once you are finished removing the outer fender, you can proceed to cut out the inner fender.
Using flange pliers make a ½” flange along the top and both ends of the panel. Once the panel is in place you will be welding along this flange.
Now you are ready to drill 1/8” holes along the top of your opening when you will fasten your new panel into.
Clamp the new panel into place. The upper flange should be placed inside and behind the top of the opening. You should take as much time as needed to make sure you install this panel in the proper location. Once it is welded into place, it is very problematic to fix.
Using fasteners, attach the panel using the already drilled 1/8” holes. With the panel in place you can now weld it. First, use a series of tack welds to hold the panel in the proper location. Next, you can remove your fasteners and continue to weld the panel on. When welding, make smaller welds (like spot welds) and try to avoid long welding beads, as they may warp the metal.
With your new panel installed you can now clean up the seams, sanding and welding as needed, and make the area ready for primer and paint.