The 1963 model year marked a significant shift in how General Motors designated its performance options for the Corvette. Moving away from the three-digit codes of previous years, GM adopted an alphanumeric system, and with it came the now-iconic “Z” prefix, reserved for “special performance equipment packages.” Leading this charge was the very first of its kind: the Z-06 (originally styled with a dash). This designation, the Z-06, immediately signaled a Corvette built for more than just cruising; it was engineered with serious performance in mind.
Initially, the 1963 Z-06 package was an all-encompassing performance upgrade, designed to transform the C2 Corvette into a formidable competitor on the track. Enthusiasts who opted for the Z-06 in the early part of the model year received a comprehensive suite of performance enhancements. This included heavy-duty drum brakes for enhanced stopping power, a robust heavy-duty suspension system to sharpen handling, and distinctive knock-off wheels. Adding to the endurance racing pedigree, the package also featured a substantial 36.5-gallon fuel tank, designed to reduce pit stops in long-distance events. While fuel injection, a four-speed manual transmission, and positraction rear axle were mandatory options for the Z-06, they were not technically included as part of the Z-06 package itself, highlighting the focused nature of the performance upgrades.
Alt text: Side view of a silver 1963 Chevrolet Corvette Z06 split-window coupe on a racetrack, showcasing its iconic design and performance stance.
However, the initial configuration of the 1963 C2 Corvette Z06 package was short-lived. By February of 1963, General Motors made a pivotal change. The large 36.5-gallon fuel tank and the sought-after knock-off wheels were removed from the standard Z-06 package. These components were then made available as individual options, designated P-48 for the fuel tank and N-03 for the knock-off wheels. Despite being offered separately, the P-48 fuel tank never saw factory installation due to issues with porosity in the knock-off wheels. This porosity problem prevented the wheels from maintaining proper air pressure, making them unsuitable for production vehicles. As a result, the second iteration of the 1963 Z-06 package became more streamlined, consisting solely of the heavy-duty brakes and heavy-duty suspension. This reduction in included features led to a price adjustment, bringing the cost of the Z-06 package down to approximately $1200. Interestingly, with these changes, the Z-06 package theoretically became available for convertible Corvettes, although the large fuel tank, which was no longer part of the standard package, was physically incompatible with the convertible body style. This has fueled debate and some controversy over whether any factory-built Z-06 convertibles actually exist, with anecdotal evidence suggesting that some were modified after purchase to resemble Z-06 specifications, like Dick Guldstrand’s SCCA racing convertible built using coupe Z-06 components.
Alt text: Close-up view of the heavy-duty drum brakes of a 1963 Chevrolet Corvette Z06, highlighting the cooling fins and robust construction designed for track performance.
The evolution of the Z-06 package continued into the following year. For the 1964 Corvette model, the heavy-duty suspension and heavy-duty brakes, previously bundled in the Z-06, were unbundled once again and assigned their own option codes. The heavy-duty suspension became option F-40, and the heavy-duty brakes were designated J-56. While the Z-06 package itself was discontinued for 1964, customers could still effectively recreate either the original or the revised 1963 Z-06 configuration by selecting these individual performance options. Furthermore, 1964 marked the year that knock-off wheels finally became a plant-installed option, addressing the earlier production challenges.
The “Z” prefix, pioneered by the original C2 Corvette Z06, has endured as a symbol of Chevrolet’s special performance equipment packages. This legacy continues to this day, exemplified by options like the modern Z-51 package. The current Z-51 option, for instance, is considered a package because it combines the FE3 suspension with a power steering oil cooler, echoing the original Z-06’s philosophy of bundling performance-enhancing components.
Alt text: Historic black and white photo of Zora Arkus-Duntov standing proudly next to a Chevrolet Corvette Grand Sport race car, showcasing his pivotal role in Corvette performance engineering.
Despite its performance-oriented design, the initial 1963 C2 Corvette Z06 package faced some challenges in achieving its racing aspirations. The most significant issue was the brakes. Ironically, some racing teams discovered that the J-65 brake option – metallic brake linings used with the standard drum castings – actually delivered superior track performance compared to the heavy-duty Z-06 brakes. After extensive experimentation with various brake lining materials, Zora Arkus-Duntov, the father of the Corvette, ultimately recognized the limitations of the heavy-duty drum brake package. It became apparent that, regardless of modifications, a production-based Sting Ray would struggle to compete directly with the significantly lighter and nimbler Shelby Cobra on the racetrack.
Zora Arkus-Duntov’s ultimate solution to achieve true track dominance was the Corvette Grand Sport. However, this ambitious program faced premature termination by GM management before the required 100 production examples could be completed. This production number was necessary for homologation as a GT car under FIA (Fédération Internationale de l’Automobile) regulations and as a production car with the SCCA (Sports Car Club of America). Consequently, the Grand Sports were relegated to competing in the FIA prototype class and SCCA C-Modified, forcing them to race against purpose-built race cars rather than production-based “silhouette” cars. Despite this considerable disadvantage, the Corvette Grand Sports achieved remarkable success and etched their names into racing legend, and the Grand Sport nameplate continues to represent high performance Corvettes today.
Regarding the origin of the “Z” prefix for special performance packages, it is often speculated that it is a tribute to Zora Arkus-Duntov himself. While it aligns with the first letter of Zora’s name, it’s plausible that the decision to use “Z” was simply a coincidence. Regardless of its specific origin, the “Z” prefix, starting with the iconic C2 Corvette Z06, has become synonymous with high-performance Corvettes and represents a significant chapter in automotive and racing history.
