Paint & Body Special SectionAn 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.
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.