What’s the rustiest part of your car’s body? If you’re the owner of a 1966-’67 A-body Chevelle and the trunk lid weather seal has been crumbling rubber for years, the rustiest part is probably the trunk floor.
Readers of our sister pub Chevelle magazine might recognize this 1966 Chevelle (well, technically a Malibu) since it was the topic of several tech articles featured within that brand’s final editions. For those unfamiliar, the ’66 was located in Southern California’s high desert in the hands of its second owner. The guy drove the 220hp 283/overdrive three-speed ’66 into the ground and then parked it with dreams of a future restoration. Of course, that never took place.
The used parts needed to convert to ’67 Chevelle front disc brakes were left inside the trunk wrapped up inside a fluffy, cotton comforter and forgotten. The ’66 sat outdoors and weathered desert monsoon rainstorms under a leaky blue plastic tarp for several seasons. It wasn’t discovered the trunk floor had rusted out until the seller opened the trunk to show us how rust-free the car was. We thought the guy was going to cry; he knocked a thousand bucks off the price and we hauled the ’66 home.
Our first piece of advice for any A-body Chevelle owner is to inspect your trunk seal ASAP and make sure it’s watertight. Hit it with a garden hose and then see if it leaked water. The steel trunk seal (weatherstrip) retaining lip is short and the trench shallow so keeping water out is on the shoulders of the condition of the trunk seal.
There are different approaches and levels of quality to restoring a rusted-out trunk floor. For my ’66 Chevelle I was after the highest-quality parts, best craftsmanship and related materials. An order went out to Auto Metal Direct (AMD) for a 1966-’67 full OE-style trunk floor (PN 800-3466) and a call to Harold’s Hot Rod Shop in Enid, Oklahoma, to make an appointment.
The high quality fit and finish of AMD’s sheetmetal is renowned in the automotive restoration industry. And whether it be a 1961 Corvette winning its class at the 2019 Grand National Roadster Show or a Jaguar E-Type scrutinized as flawless on the lawn at Pebble Beach, the finished work Harold’s Hot Rod Shop produces is beyond compare.
Replacing the trunk floor is only the beginning of the bodywork and paint Harold’s Hot Rod Shop is undertaking on this Chevelle. After installing the AMD trunk floor, the body was mediablasted and primed in PPG VP2050 DTM High Build Primer and is headed toward a show-winning finish in PPG Tropic Turquoise; its original hue. Look for additional body, paint, and high-performance suspension and drivetrain tech features on this ’66 Chevelle in upcoming editions of Super Chevy in print and online.
All the hand tools Harold’s Hot Rod Shop needed to remove and replace the AMD 1966-’67 Chevelle trunk floor (pan). The Chief Multispot MI200T spot welder (not shown) made for welding high-strength steel accounted for 80 percent of the welding. You can use a MIG, but the spot welder is fast and how the factory did it.
Installing repair sections of the trunk floor only requires removing the gas tank and rear bumper. Replacing the entire trunk floor is a major undertaking, requiring the complete removal of the body from the chassis, because, in some cases, a patch panel just won’t cut it.
A brief squirt with a garden hose reveals where water enters the trunk. The passenger-side rear antenna was a factory-installed option on this car and is a common spot for leaks, along with bad/worn weatherstripping.
With the gas tank out and the trunk lid open, sunlight will expose the rust holes; there were a lot! It was then time to start unbolting the body mounts.
The front clip, fenders and core support with grille attached were removed, and then the body mounts were unbolted and the body from the firewall back was lifted off. Obviously, this is a good time to replace body bushings and do other work to the chassis.
Since the wheeltubs were rust-free they were left in place. Leaving the wheeltubs in place provided enough strength so it wasn’t necessary to weld in crossbraces to prevent the body from springing out of shape.
Using 3M 05916 welding and spark protection paper to protect window glass is a good practice. Next, the trunk lid was removed to gain easier access to cut out the rusted trunk floor.
First marking a straight line to follow and then with a 4-inch cutoff disc on a die grinder, Josh cut out the main portion of the trunk floor.
Notice the cuts were made close to the seams, but not at the seams. For the next step, a spot-weld drill bit was used to drill out the spot welds. That was followed with a hammer and sharp chisel to split apart the seams.
Notice the AMD trunk floor one-piece stamping (PN 800-3466) replicates the appearance of the OEM trunk floor exactly. A clean installation guarantees the new AMD trunk floor will be undetectable from a perfect, rust-free factory installed floor.
Before installing the trunk floor, it’s a good idea to test-fit it to the chassis and check things like the alignment of the mounting holes. Everything lined up perfectly.
Rust starts at the seams where water and moisture collect. The benefits of a good weld-through, copper-rich primer include better penetrating spot and tack welds and long-term rust protection. The seam edges should be straight and fully trimmed away to ensure a proper fit. Note how the coverage of the weld-through primer is done.
From the factory, the rear panel is spot-welded to the quarter-panels. The rusted floor is cut out first and then the rear panel is cut out and removed.
We inspected the rear panel for rust damage, primarily along the bottom. This rear panel was rust-free so it was sent out for mediablasting and then sprayed with PPG VP2050 DTM High Build Primer.
Here’s how the Chevelle looked prepped and ready for refitting the trunk floor. Inside the trunk lid reveals the original Tropic Turquoise color.
The trunk floor held in place with genuine vintage Vice Grip brand locking pliers made in DeWitt, Arkansas. When doing projects like this, you can never have too many locking pliers.
An added bonus to spraying a good weld-through, copper-rich primer is it will serve as a guide to position the trunk floor in its correct place.
The Chief Multispot MI200T spot welder made for welding high-strength steel was able to reach 80 percent of the welds. The remaining 20 percent was handled with a MIG. For the MIG sections we used a pneumatic punch to makes holes along the seam, but a drill works if you don’t have the fancy tools.
Immediately after the trunk floor was fully welded in place, the seams were caulked to seal out any chance exposure to rust-causing moisture.
This photo was taken weeks after the AMD trunk floor installation was completed and shows the exterior of the Chevelle has been sprayed with PPG VP2050 DTM High Build Primer.
Photography by John Gilbert