Paint & Body Special Section
An item on the '74-and-up Corvette that is considered so significant that it is a defining feature is the urethane bumper arrangements. Designed to meet the new federal crash standards phased in during the '70s, the bumper arrangement represented a major change in the Corvette. Beginning in 1973, on the front only, and then appearing at both ends for 1974, these urethane bumper covers were innovative for their time, hiding a massive impact-absorbing system behind them. Gone were the elegant chrome bumpers of earlier Corvettes. Undeniably, the change had a major impact on styling, though arguably the form created by GM was very attractive in its own right. Still, the change is significant enough for a distinction to be made, separating C3 Corvette types between "chrome bumper" and "rubber bumper" cars, with the former considered more coveted.
Front bumper finished and...
Front bumper finished and bonded with Mar-Glass bond.
Starting at the rear, the...
Starting at the rear, the first step is to remove the taillights and hardware from the stock urethane cover. use plenty of penetrating oil on the fasteners before trying to unwind them.
Although the bumper caps unbolt,...
Although the bumper caps unbolt, the original fasteners are usually rusted and hard to get to and remove. instead of dealing with the fasteners, we simply cut the stock cover off the car right near the flanged end with a cut-off wheel in a die grinder.
The new bumper technology was not without its problems. Though the concept is virtually universal in modern vehicles, the technology of a flexible urethane cover was in its infancy at the time of its introduction on the Corvette. Without a doubt, the major detraction was the material's inability to hold its original shape over time. Perhaps the "flexible" nature of the cover was an aspect taken a little too far. For the rubber bumper Corvette owner, distortion and waves in the covers' sleekly styled lines is just a fact of life.
There are a number of solutions available to rubber-bumper Corvette owners. Of course, the covers can be replaced with new OEM covers, but the distortion problem will eventually return. The aftermarket has semirigid fiberglass replacements, which are not nearly as flexible as the originals, but have enough flexibility to conform to the rigid body panels, allowing bolt-in installation as upgraded replacements in most cases. The third alternative is a rigid fiberglass replacement for the original covers. Being rigid, these covers do not have the conformability to mate directly to the hard body panels. For a bolt-in installation, typically the panels need to be fitted, filled, and ground until the cover mates to the body with an identical seam. This involves adding filler as needed to either the body or cover, and/or finish grinding and sanding both until the profiles come together with a perfect seam.
Instead of hours of frustration...
Instead of hours of frustration with the mounting bolts, we had the cover off and on the ground in minutes by cutting it off. note the massive bumper structure hidden behind the cover.
Since our car was intended...
Since our car was intended more for track performance than street duty, the entire structure of the rear bumper reinforcement was removed. Six bolts per side, and the whole works came out as an assembly. the result is less weight than an early chrome bumper rear.
What's left of the rear cover...
What's left of the rear cover is the flange, the fasteners, and the metal strip. Since this hardware is rusty and timeconsuming to remove, a cut-off wheel in a die grinder was used to cut through the studs where they mount to the body, allowing the metal mounting strip and remaining flange to be removed in minutes.