How To Start a Budget C3 Corvette Build: Body Basics

They look amazing in any situation, but fools rush in where angels fear to tread. Because they aren’t like anything else on the road, we have a bit of advice to help you make an informed decision.
Corvette Manta Ray 7 photos
Photo: GM Heritage Center
Corvette Headlight UpgradeTypical Corvette C3 Dash RustUse A C5 Ground Harness For InspirationCorvette C3 Body MountsC3 Corvette Bonding SeamsCorvette Body Mounts
Corvette’s 3rd generation reigned from 1968 to 1982, and it witnessed everything from the Apollo Program to the “War on Drugs.” It was inspired by a wild Mako Shark concept car, with many unique features fitted to make it a functional part of your family.

The Mako Shark II was a concept car from 1965 that was low and lean, with fenders almost blocking the passenger’s line of sight. Penned by Larry Shinoda, it echoes the same '60s vibes that also inspired the Lamborghini Miura and DeLorean’s Pontiac Banshee concept. While those cars were watered down before production, Chevrolet decided to build what the people were begging for.

Continual updates kept the car ahead of critics, with nearly 54,000 Vettes sold in 1979. They can be found in every possible state of disrepair, with entire industries based around keeping them roadworthy. So, if you have been fascinated by the prospect of a rewarding project, here is what you need to realize.

Corvette Body Mounts
Photo: General Motors
Of course, the body is fiberglass. But instead of the one-piece tubs we are spoiled with today; the panels contain a steel framework that’s known as the ‘Birdcage’. Cars back then weren’t supposed to last more than a decade, so that’s how long it takes for rain to rot a Vette from the inside out. When I inspect anything older than 1984, the dashboard and the firewall are the first spots to check.

To give the Corvette the ultimate grip in the corners while being comfortable on the street, the body is used as a stressed member of the car, and it's held onto the chassis with six massive bolts. Not only do their rubber bushings evaporate over the years, and the body mount brackets don’t have drain holes...more rust. Once those are happy again, it's time for fiberglass work.

Because the body is kept in tension, stress cracks form around the headlight buckets and sometimes along the rear quarter panels. Reach under the front fenders to feel for frayed fiberglass, it's an easy way to check for a history of abuse. The body panels are glued together at bonding seams, so grab a Corvette owner to join you on the inspection.

Now that your wallet is lighter, allow my misfortune to save you intense frustration. Fiberglass doesn’t conduct electricity, so everything electrical must have its own ground. Corvettes of all ages have solved this problem with dedicated ground harnesses that tie back to the negative battery post.

Corvette Headlight Upgrade
Photo: Mid America Corvette
Take an afternoon and make a new ground harness, using a C5 Corvette as inspiration. Take a roll of black wire, and run grounds to the headlights, running lights, gauges, radio, and amplifier while leaving a few extras for phone chargers and fuel injection down the road.

Don’t worry about the headlight motors, because there are none. The C3 makes use of vacuum lines and actuators to move the headlight doors, HVAC servos, and the windshield wiper cowl (until 1973). Therefore, order 20 feet of rubber hose and print out the diagram for your year. Keep in mind that late-model LS engines don’t have enough manifold vacuum to keep the system happy, so upgrading to modern electronics is a great way to make use of that new ground harness.

My 7th Corvette build will commence in a few days, so follow along as I dive into the suspension, brakes, and climate control while Florida’s 4 weeks of Winter provides the backdrop. Happy New Year’s from all of us at autoevolution!

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