What A Difference A Bowtie Makes
On display for over a year at Disney World’s future-inspired EPCOT Center (known now simply as Epcot), GM’s series of non-running Aero concepts were little more than theoretical studies in aerodynamics for the engineers, and props for theme park tourists to gaze at. That is, until 1984 when engineers from one of its divisions set out to change that.

1984 Crevrolet Citation IV ConceptEnter the 1984 Chevrolet Citation IV concept. At first glance, there appears to be little changed from its GM-badged predecessor. With regard to its exterior shape, that’s an accurate assessment. However, it’s under the red fiberglass skin and behind the tinted glass where the significant differences reside.

Under Chevrolet, the Aero 2002’s spirit was transformed into a fully functioning car. The task was anything but ordinary since the shape had been dictated by the wind, not conventional engineering practices.

1984 Chevrolet Citation IV Concept ergonomicsSince the GM-badged Aero 2002 lacked components essential for motoring such as outside mirrors, windshield wipers, and trifle things like a drivetrain and functional interior, engineers had their work cut out for them. And they were to be confronted with new challenges as a result of the unconventional design. The task was accomplished using not only customized approaches and unique technologies but also several borrowed parts; however, not from its namesake.

From Clay Shell to Customized Concept
1984 Chevrolet Cavalier convertibleTo start, drivetrain engineers looked to GM’s then-recently introduced J-platform. (The J-platform was one of GM’s small, FWD offerings introduced for the 1982 model year and sold through the Chevrolet, Pontiac, Oldsmobile, Buick and Cadillac divisions. The red one pictured to the left is a 1984 Chevrolet Cavalier convertible.) Notable portions donated to the concept from the J-platform were brakes and rear suspension.

The Citation IV’s front brakes were 9.7 x 0.5-inch discs, while the rear employed 7.9 x 1.8-inch cast-iron drums. Braking power was boosted by a newly developed Delco electric pump, in an effort to save space.

The aft suspension was a transverse beam with trailing arms, on (conical progressive rate) coil springs, with incorporated stabilizer bar.

1984 Chevrolet Citation IV Concept front suspensionThe front suspension, was somewhat more unique. Non-standard engine and drivetrain positioning dictated Citation IV’s short-/long-arm (SLA) geometry front suspension borrow yet again from another production Chevrolet vehicle. This time, it wasn’t a direct swap and it wasn’t from a lowly compact.

Engineers used a transversely-mounted, modified version of the Corvette’s unique single-leaf, fiberglass composite spring. Suspension components and connection points were specific to the concept’s needs, as were the tunable large-rear/small-front control arm bushings.

The rack-and-pinion power steering system could be considered advanced for the time in that it was electrically (rather than hydraulically) assisted. This, as with the electric brake pump, was done in order to save space but also contributed to efficiency by replacing the engine-driven hydraulic pump with one driven by a DC motor, separate from the one used for the brakes. The amount of steering boost was variable, depending on vehicle speed; a feature many take for granted today.

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