By John Gunnell
Reproduction Camaro body panels are readily available, but sometimes it's just as easy and cheaper to fix small rust holes in sheet metal. Keep in mind that the actual size of a rust hole is rarely what you see at first. It's what you wind up with after poking and cutting out rusty metal. What starts out as a small opening can become a huge crater. If you have a crater, you'll need new floor panels. These come single-piece (complete floor) or as right- and left-hand panels that run the full length of the floor on each side of the transmission tunnel.
For small holes, cut out bad sections of the old floor and trim replacement panels to fit inside the cut out area. Then butt-welded them in place. Butt-welding eliminates overlapping sheet metal where corrosion could re-start. Use a MIG welder to hold the trimmed panels in place. Put tack welds at all four corners and fill in with tacks every few inches around the perimeter. Once everything is tacked, weld different areas a few inches at a time to keep the pan from heating up and warping. Wear a welding helmet and heavy welding gloves.
If the rotted floor area is not too large, cut out the bad stuff.
Once all the welding is done, the welds underneath the car can be ground smooth. Leave a little weld on the top for extra strength. Then use waterproof fiberglass filler to provide strength. Apply standard filler over the repair for final shaping and forming. Then use epoxy-based Spot Filler putty for final fills. This putty is much thinner than Bondo and fills in sanding scratches and air holes.
After butt welding trimmed section of replacement panel in place, dress the weld and finish off underside of repair with fillers.
Cutting out the bad sections of the old floor can be tricky, so do this carefully and try to get the best tools that make sense for you. An Air Whizzer tool and an air saw with a very small thin blade can be used. An angle grinder and cut-off wheel works, too. Another option is an air-powered chisel if you have a big compressor that won't leave you high and dry on air every few seconds. Ultimate is a plasma cutter. The cover of the latest Eastwood catalog shows a floor being cut open with a plasma cutter that Eastwood sells for a hobbyist-friendly $640. If you do a lot of work on cars, this tool may be worth buying. If you're only doing the one car, perhaps you can borrow one or use other tools.
Corrosion in the windshield channel area is common. This is the "lip" that the windshield glass sits against. Cancer occurs due to water seeping behind the 40-50 year old bead of dried-up gap sealer and laying in that area for a long time. Adding to the problem is that late-1960s automobile production processes did not ensure that the metal lip was always well protected by primer or paint. In addition, the factory finishes used back then were not up to lasting a half century. This created a situation where moisture tended to collect where there was bare metal or where finishes wore off. This made the channels very rust prone. The same was true for the rear window channel on closed cars. In both cases, the problem and cure are the same, so rear window rust repair is very similar.
After removing the glass, cut out the corroded spots using the Air Wizzer cutting tool. Take out all the rust until hitting solid metal. Then, use pieces of 90-degree angle sheet metal to cover where the cancer was cut out. Cut notches in the angled strip so that it can be formed to match the contour of the windshield.
Cut out rot in windshield channel.
Weld angle into the area you cut out in the windshield channel.
Once each angle piece is tack welded into position, the perimeter and the notches can be welded up using a MIG welder. Remove any excess weld by using the Air Whizzer and die grinder. Try to keep the repaired area from extending into the roof panel. This way, most of the windshield channel that repairs had been made to will be covered by the bright metal windshield trim.
Clean up the weld with a die grinder or air whizzer.