C4: History of the Corvette - 1984-1996
To the Next Level
Drew HardinWriterGMPhotographer
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.
VETTE sister publication Motor Trend devoted a big part of its March ’83 issue to the 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 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, 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, and it 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 resulting L98 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.
As the C4 was making its debut, Corvette engineers and product planners were looking down the road at ways to keep the Vette the top-of-the-heap halo vehicle Chevrolet needed it to be. It was feared the incremental power gains squeezed from the L98 weren’t going to be enough to fend off foreign competition.
So McLellan put Chevy’s powertrain people to work. Early experiments at turbocharging didn’t pan out, but the engineers were encouraged by the potential offered by overhead camshafts and multiple valves in the heads. Following this path led to an arrangement with Lotus, with whom GM designed an all-aluminum, 32-valve, dual-overhead-cam V-8. Once the design work was completed to Chevy’s satisfaction, manufacturing of the engine was turned over to Mercury Marine in Stillwater, Oklahoma.
The overhead-cam design made for a small-block with a wholly different character, a high-winding motor that didn’t hit its 375-horse power peak until 6,000 rpm. McLellan knew putting all that power to the ground meant installing fatter rear tires, which would also necessitate wider rear-end bodywork. To further set off this new super Vette, the car’s round taillights were squared off.
The engine was named the LT5, and early prototypes of the Vette had an LT5 badge under the passenger-side taillights. GM brass didn’t want to use the engine’s RPO code that way, though, so production versions were badged with the car’s official name. Though early in its development Chevrolet Chief Engineer Don Runkle called it the “King of the Hill,” the company went back in time to revive a high-performance RPO number from the early ’70s: ZR-1.
Journalists first tested the car in Europe after its debut at the Geneva Auto Show in 1989. Though it was intended to be an ’89 model, by the time all the engineering was sorted out, the corporation tagged the cars as ’90s.
The ZR-1 was an incredible performance machine. Motor Trend clocked the car at 4.75 seconds from 0-60 and 13.13 seconds through the quarter-mile, while the hot shoes at Car and Driver dipped into the high 12s. Yet the ZR-1 RPO carried an equally stratospheric price tag: $27,000 over the $32,000 cost of a ’90 coupe to base it on. Despite that steep sticker, some 3,000 ZR-1s were sold in the model’s first year.
All told, the ZR-1 option was available from 1990 to 1995, and the car saw minimal changes during that time. Output rose to 405 hp in ’93, the same year Corvette celebrated its 40th anniversary. That was also the year Mercury Marine stopped making the LT5 engine, leaving enough of a surplus to continue building the car in limited numbers for two more years.
There were several reasons for the ZR-1’s short life. A stagnant economy made it hard for Chevrolet to find buyers who would pay the car’s steep price, and getting the LT5 to pass the stricter emissions standards for the upcoming ’96 model year would have been prohibitively expensive.
Plus, the standard Corvette was going through a series of upgrades that closed the gap between it and its supercar brother. First came a new look: All Corvettes received the ZR-1’s squared taillights in ’91, in addition to a revised front fascia, new fender louvers, a new turbine-style wheel design, and the Z07 adjustable-suspension package, which replaced the Z51 option. Then in ’92 the L98 small-block V-8 was replaced by the first of the Gen II small-blocks. The new 350-inch motor, named LT1 after the LT-1s from the ’70s, was good for 300 hp—a significant increase.
Another milestone passed in 1992, as Dave McLellan retired and handed his Chief Engineer job to David Hill. Hill had come from Cadillac, but he had extensive personal experience with sports cars, both foreign and domestic.
That changeover happened just a year shy of the Corvette’s 40th anniversary, which was commemorated in the ’93 model year with a 40th anniversary package: Ruby Red Metallic paint (with leather upholstery to match), special emblems, and body-color wheel centers. Also new for the model year was the first keyless entry system.
The ’94 model year saw several changes to the Vette’s interior. Leather upholstery became standard (and cloth unavailable), the steering wheel and instrument panel were redesigned, and there was now an airbag in front of the passenger seat. Underhood the LT1 was fitted with a new sequential fuel-injection system that improved throttle response and lowered emissions, though output numbers remained the same.
Corvette paced the Indy 500 for the third time in 1995, and 527 pace-car replicas were built, each finished with the Indy car’s distinctive purple-over-white paint scheme. Standard ’95 Vettes received revised front fender louvers and softer springs, while the big front disc brakes that were part of the ZR-1 and Z07 packages became standard on all Vettes.
By 1996 the much-delayed fifth-generation Corvette was finally waiting in the wings, as was an all-new small-block V-8. Chevy marked the end of the C4 era with not one but two special one-year-only models. As it did with the last shark in ’82, a Collector’s Edition was offered, with special paint, wheels, upholstery, and badging.
The second special was called the Grand Sport, an homage to the racing Corvettes spearheaded by Duntov in 1962. The Grand Sports were finished in Admiral Blue paint with a white stripe down the car’s center and two red hash marks—or “Sebring stripes”—on the driver-side front fender. Grand Sport coupes were shod with black painted ZR-1 wheels and fitted with rear fender flares to cover the wider rear tires, while convertible Grand Sports received the standard Corvette wheel-and-tire package.
The Grand Sport was no mere appearance package, though. Under the hood was a highly modified LT1 with freer-flowing heads, bigger valves, a more aggressive cam, 1.6-ratio roller rockers, and high-flow intake manifold. Called the LT4, this Gen II swan song put out 330 hp and 385 lb-ft of torque, and it was dressed for success with bright red accents and a “Grand Sport” plate on the throttle body. While the pumped-up engine was initially planned as a Grand Sport exclusive, Chevy ultimately decided to install the LT4 in all six-speed Vettes for ’96, while cars fitted with the 4L60E automatic received the standard LT1.
In addition to the C4, another Corvette legend passed in 1996. Zora Arkus-Duntov, whose legacy would forever be intertwined with his beloved sports car, died in April of that year. Duntov never did see his mid-engine dream car become a reality, but he was able to attend the opening of the National Corvette Museum in Bowling Green in 1994, which must have been deeply satisfying for the man who almost singlehandedly saved the Corvette from certain death in the mid ’50s.
Genesis:
These illustrations and styling models show how the look of the C4 evolved in the late ’70s. The car came together in a fairly short period of time: the front-engine concept sketch was done in 1978, and the final fiberglass model was finished in 1980.
