Advanced Vehicle Systems was founded by Don Nichols in California in 1968 and the cars they built were called Shadows. Designed by Trevor Harris, the early cars were raced under Shadow Racing Inc. and driven in the CanAm series by George Follmer and Vic Elford. Dubbed the MK I, the ingenuity and creativity could be seen throughout the vehicle, particularly in the small wheels which reduced drag. The forward-thinking was not enough in the highly competitive CanAm series, with their efforts often crippled by reliability issues. Smaller tires also meant smaller disc brakes and rotors and reduced ability to dissipate the heat.
Peter Bryant and the Autocoast company were also innovative, proven by the introduction of their titanium 'Bryant Ti22' in 1969 at Laguna Seca. The chassis was a monocoque structure comprised of aluminum and titanium. Jackie Oliver drove it in its racing debut to a 13th-place finish. Oliver continued to race the Ti22 throughout the 1969 and 1970 seasons, cut short when the car flipped off the track on the first lap of the second race of the season. A second chassis was built but only in time to compete at the last two races of the season. Due to a lack of funding, Bryant joined forces with Shadow bringing Jackie Oliver along with him. They began work on a new racecar that would combine the strengths of both previous cars. Jackie Oliver was assigned driving duties and Universal Oil Products became the team's official sponsor.
Although Nichols favored the minimal frontal area philosophy, he was willing to make some concessions such as switching to Goodyear Formula 1 tires which were slightly larger than the previous Firestones. This allowed Bryant to pen a more conventional design with a better seating position for the driver. Once again, the small disc brakes were prone to overheating. The use of inboard brakes helped dissipate the heat but introduced another potential problem, as the shafts used to connect the discs to the wheels could fail. The suspension followed a conventional design and the frontal area was used to house the radiator. A wing was mounted above the radiator intake and complemented the strut-mounted wing located behind the rear axle. The body was made from fiberglass and a Chevrolet V8 big-block engine was backed by a Weismann gearbox. The engines were built by Jim Hall at Chaparral and featured the unique cross-ram intake system. This induction system reduced aerodynamic drag, but it limited horsepower. For the final two races in 1971, the induction system was replaced by a conventional vertical stack system.
The rear inner wheel shells from the MK I were retained and used for the front wheels on the MKII, but little else remained. The same was true of the Ti22, with only small amounts of titanium incorporated into the design of the MKII. The monocoque chassis was made from aluminum while the rear engine mounts and a few other small portions of the car used titanium.
The new Shadow MK II raced in eight races during the 1971 season, missing the season opener at Mosport as the car was not ready in time. As it was a completely new car, a new design, a new team, and with little time to properly prepare and test, the MKII suffered reliability issues throughout the season. Despite its Achilles Heels, it did qualify in the top five in all but one of the races. Driven by Oliver, it qualified second at Road America and finished third at Edmonton. This would be the car's second and final time that it actually made it to the checkered flag.
Further development work continued in the off-season in preparation for the 1972 season resulting in the name being changed to the MK III. It used the same tub but with extensive modifications made throughout the vehicle. Among the most significant was the abandonment of the low profile front area allowing for larger wheels and changes to the suspension geometry. Two separate radiators positioned on either side of the driver replaced the single front-mounted unit. The MK II of the 1971 season was upgraded and renamed the MK III. A second example was completed midway through the season. A total of three MK II and MKIII tubes were eventually built, with two tubs currently in MK III specification. Shadow had built two complete cars with the spares later sold off to privateers. The current MK II (chassis 71-3) was built by a Shadow enthusiast and completed in 2011.
With Oliver at the wheel, the Shadow placed second at Mid-Ohio and third at Donnybrook during the 1972 season. Reliability was once again an issue, and the newly introduced turbocharged Porsche 917s provided new levels of competition. With the second MKIII, Shadow was able to experiment with various technologies such as adapting turbochargers to the V8. It proved potent but the Weismann gearbox was unable to cope with the increase in power. Nichols eventually forfeited his all-American philosophy and switched to a Hewland gearbox.
When the MK II / MK III was able to make it to the finish line, it was often in a podium position. Going into the 1973 season, Shadow hired designer Tony Southgate to aid in their Formula 1 endeavor. He was also tasked with designing a new Can-Am car which later brought Shadow and Oliver the Championship Title.
by Dan Vaughan