C4: 1984-1996To The Next Level
Every new Corvette generation, it seems, misses its due date. The arrival of the fourth-generation cars was pushed back so much that GM executives decided to skip the entire '83 model year and launch the C4 as an '84 model. The first Corvette to wear the stamp of Chief Engineer Dave McLellan, the C4 was an immediate hit with buyers and the media, and it achieved several landmark milestones during its 13-model-year run. McLellan and company had, indeed, taken America's favorite sports car to a whole new level.
Evolution vs. Revolution
Motor Trend devoted a big part of its March '83 issue to the brand-new Corvette, and within that special section was an article by Jim Hall describing the car's genesis, a case of evolution versus revolution. Was it finally time to make Zora Arkus-Duntov's revolutionary dream of a mid-engine Corvette a reality, or should the car take an evolutionary approach and retain its front-engine/rear-drive layout?
As far back as 1976, the Corvette engineering group and the Chevy 3 design studio were drafting proposals examining each of those architectures. The designers favored Duntov's dream and worked up a clay model based largely around the Aerovette show car. McLellan and his engineers built a mid-engine mule to study the design using a Porsche 914 platform. They realized packaging constraints would force them to use a V-6 in a mid-engine Vette, and the only engine available at the time was the anemic 2.6-liter six-banger available in the X-cars. It was deemed too expensive to power up that engine with a turbocharger, so the engineering team discarded the mid-engine concept, though the designers held onto the dream for a while longer.
Reportedly it was the introduction of the front-engine/rear-drive Porsche 928 in 1977 that put the final nail in the mid-engine Vette's coffin. At that point the mid-engine concepts became "experimental" vehicles once again, and Chevy 3 was tasked with designing a Corvette with the conventional powertrain layout.
The new car, they were told, had to have more interior room and more cargo capacity, but it had to be shorter overall, have a better firewall-to-axle proportion, and have a lower drag coefficient. Oh, and it had to look like a Corvette. An early rendering, done in October 1978, set down the C4's basic shape, though the car's nose looked a lot like a Firebird's.
It was packaging, in the end, that determined the car's look. To reduce height while not impacting ground clearance, the engineers tucked the exhaust system up into the center tunnel. The windshield pillars were dramatically raked back; and the car's fuel-injected motor was positioned lower in the car, allowing a low hood line. For a while the designers incorporated cooling grilles into the car's nose, but the bottom-feeding radiator didn't need the airflow, so the grilles were replaced with light lenses. A fiberglass model finished in early 1980 was nearly identical to the production version that went on sale in March 1983.
Beneath the skin the C4 was all-new, too. Transverse monoleaf springs were used at both ends of the car, rack-and-pinion steering was fitted, and the independent rear suspension now used five locating links instead of three. The previous year's 350ci Cross-Fire V-8 (now making 205 hp) returned, as did the 700-R4 automatic transmission, though the Vette could now be ordered with a Doug Nash four-speed manual, which earned the "4+3" nickname for the computer-controlled overdrives in the top three gears. A new Z51 performance suspension was available as an option, which helped the car earn near-1g lateral-force figures in skidpad testing.
Inside, the new interior marked the first use of an all-digital display instead of traditional analog gauges. While it looked high-tech at the time, the instrument panel met with decidedly mixed reviews. The '84 Corvette was a big hit. High demand and an extended on-sale period netted sales figures of more than 51,000 units, and the car earned all sorts of media accolades, including Motor Trend's Car of the Year award.
Good as the C4 was out of the box, revisions started almost immediately. For the '85 model year, the small-block's Cross-Fire throttle-body injection was replaced by Tuned Port Injection, and the new L98 small-block made 25 more hp, 40 more lb-ft of torque, and got better fuel economy. While the press loved how the new Vette's suspension handled around the skidpad, in the real world customers were complaining about the car's stiff ride. So spring rates were softened for both the stock suspension and the Z51 sport package.
In '86 the Corvette ended its 11-year open-air hiatus with a new convertible model. McLellan had a drop-top in mind when designing the C4, so it didn't take a tremendous amount of extra chassis bracing to make up for the lost roof panel. Antilock brakes became standard equipment aboard the Vette, and aluminum cylinder heads were available as a mid-year addition, adding 5 hp to the L98's output.
For the second time a Corvette paced the Indianapolis 500, and as was the case eight years earlier, the car used for pace duties was essentially bone stock, save for safety gear and strobe lights. In '87 the L98's output rose again, to 240 hp, thanks to a change from traditional hydraulic lifters to roller lifters. New for the year was the Z52 suspension option, a "sport" package that teamed most of the Z51 equipment -- quicker steering, Bilstein shocks, oil cooler, heavy-duty radiator, thicker front sway bar, wider wheels -- with the softer stock springs.
The Corvette celebrated its 35th anniversary in 1988, and Chevrolet marked the occasion with a 35th Anniversary Edition. Some 2,050 coupes got the special treatment, which included white paint, white wheels, white leather upholstery with anniversary embroidery, the Z52 suspension, and other goodies. All '88 Vettes saw improvements to the front suspension and brakes, and some were shod with a new six-slot wheel, which appeared only in this model year.
In '89 the Doug Nash 4+3 manual was replaced by a six-speed ZF gearbox, the infamous "skip shift" transmission. In the interest of fuel economy, this trans was outfitted with what was called Computer-Aided Gear Selection, which forced the driver to shift from First to Fourth if the gear change was made at low speeds or low rpm. Of course, most just revved their Vettes higher before shifting to avoid the annoying First-Fourth change, which didn't help fuel economy at all.
Also in '89 the 17-inch, 12-slot wheels that first appeared on the '88 Z51 and Z52 suspension packages were made standard equipment on all Corvettes, and convertible owners could now order a hardtop option with a glass rear window and fully lined roof.