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C4 Corvette - 1984 to 1996 - The 1984 Corvette

The 1984 Corvette had been a long time in coming. Since the early seventies, several different show cars promising to be the next Corvette were shown. They were mid-engined and used powerplants ranging from the conventional small block to both two and four-rotor Wankel engines that General Motors was spending millions of dollars on to perfect. The bodies were costructed of fibreglass and aluminum an looked like nothing else on the road. The quad rectangular headlamps that became a styling staple were intoduced on those cars. According to the predictors, Corvette was to be many things, all at the same time.

When the C4 was shown to the pubic, the reaction was veried. The highly stylized Mako Shark II inspired Coke bottle shape of the C3 was eschewed for a simpler, plainer Jerry Palmer creation. However, an unfortunate milestone was achieved with the introduction of the C4 Corvette; the 1983 model year would be skipped, the 1984 would follow the 1982.

It was a long wait too. Production of the 1982 ended in October of 1982, a run that was extended slightly over the the typical ending months of August-September. The new Corvette, known then as a 1983, was shown to journalists in December of 1982 at Riverside Raceway and was enthusiasticly met. They loved the shape, the handling, and the performance. The C4 was a worthy successor.

The shape of the new Corvette represented the styling theme of GM products of the 80s. That is aerodynamics were an important way to make the car look sleeker and give it the fuel economy of smaller sedans. At the front, there was no traditional grilles, the C4 was a bottom breather. Air that normally would pass beneath the car was caught by the underbody spoiler and forced upwards into the radiator. For the first time fog lamps were offered and these halogen units were integral with the park/turn signal units located in ther lower outer corners of the front fascia. A low gloss textured black rub strip formed a detail line and upon leaving the front bumper encircled the entire car. A license plate pocket was integrated and included a filler panel with embossed CORVETTE lettering for those states not mandating a front plate. The front fascia wrapped around the bodyside that became part of the front wheel opening. On the sides of the bumper cover were a lamp assembly that contained the side marker/turn signal and a turn signal activated cornering lamp.

The hood still tilted forward, but was now of a "clamshell" design that incorporated the front fenders and headlamp assemblies. The design allowed for a unobstructed view of the detailed engine compartment, revealing the race car inspired aluminum suspension castings. The headlamps no longer "popped up" but instead "rolled over" from front to back, designed with smart aerodynamic packaging for the headlamp nacele. A similar design was used way back in 1969 on another GM product, the Open GT (which itself was call a "mini-Corvette" among its followers.) On The Opel GT the headlamps rolled over from side to side. The headlamps were no longer round, instead being GMs new larger rectangular halogen units. With the fenders now being an integral part of the hood, plastic inner liners that were sealed from the elements kept dirt and grime out of the engine compartment. The hood was kept open by a metal lever support that unlike the self releasing design used on the previous Corvettes and was quite awkward to support upright and release to lower.

The windshield was laid back at an astounding 64.7-degrees, and this contributed highly to the cars .34 coefficient of drag. By comparison the 1982 cars cd was .47. The body panels of the car were constructed of SMC, short for Sheet Molding Compound, but differed in the manufacturing process of the materials used on thr C3. The panels had a thin rubberized coating applied to the panels. This was designed to keep the paint match more consistent between the bumper fascias and the body panels as the cars aged. The panels were also manufactured in such a way that there were to be no seams where panels joined. That was the job of the bodyside rub strip. The rub strip also had the words "Cross Fire Injection" embossed and tampoed in silver in the area above the gill panels. The body paint process was a new "base coat/clear coat" where the final finish coat was clear to add depth and luster to the appearance.

Instead of t-tops, the new Corvette had a single piece lift off roof panel with no bar that tied the windshield to the rear roof halo. The panel came in painted firbeglass as standard and an optional transparent acrylic panel in a blue tint. The panel was bolted in place, one in each corner of the windshield header and a pair at the leading edge of the roof halo. When removed, it was clamped into place in the cargo area. The all glass rear window was hinged at the front edge and opened in a hatchback fashion, supported by a pair of high pressure gas struts.

The rear bumper cover returned to a semi concave "kamm"tail with a pair round tail lamps on each side and two large backup lamps that sat astride the rear license plate pocket. The rear bumper fascia wrapped around the lower body and extended to the wheel opening. Rear cornering lamps were integrated into the side marker lamps and came on when the car was put in reverse. The fuel filler door was a flat panel the hinged at the front edge and the rear edge met the rear bumper cover with the Corvette emblem on top.

Inside the C4 was an incredible departure from the C3. The new interior was a technological tour de force, with an instrument panel full of digital gauges, a center console amass in switches, and seats that could have come from the set of "Star Trek". For the Corvette faithful, this was culture shock indeed.

The instrument panel was a was in bright, colored , liquid crystal display. Directly ahead was a digital speedometer with a pair of bar graphs the were patterned after horsepower and torque curves for speed and engine rpm. Between the tach and speedo was a bar graph fuel guage. There were no round dials; instead digital numeric readouts provided information for temperatures, volts, and oil pressure. The readouts were visible through a Corvette unique leather wrapped two-spoke steering wheel that incorporated aboth tilt and telescopic features. All steering wheels regardless of interior color were black.

In the IP's center, there were switches to change the dispalys for the gauges and also to control the trip computer that could display instant and average fuel economy, range, and trip distances. With a flick of a switch, the display could change from U.S. to metric values. Now cruising at 60 mph you could amaze your passengers by instantly display 100- kilometers that is. All radios were electronically tuned with seek, scan, and up to 7 AM and FM presets (with 4 buttons) The radios used a vacuum flourescent display. Optionally, a CB radio (late and limited availibility) (RPO UN8), a stereo radio with a cassette (RPO UM6)and the Delco Bose AM/FM/Cassette sound system (RPO UU8) could be ordered. A planned AM/FM stereo radio with an 8-track tape player never made it into production.

On the right side of the dashboard was a huge protuding lump- a product of the long gestation period of the car. When the interior was originally laid out, it looked like air bags would be required. The timeframe was moved back but the huge pad remained until Corvette got an interior redesign in 1990. All the instrument panels and top covers were a dark blackish color. Only the seats, carpet, console pad, and door panel inserts being presented in the interior color. The door panels included long thin courtesy lamps that came on with the interior lighting or by simply pushing them in to turn them on of off. The interior door releases were a squared off metal loop. If the optional Delco Bose sound sytem was ordered, speakers were located in the front lower edges of the door panels. On the left door panel, the windshield wiper switch was located. There wew three switches to gain access to the cargo area; a button in the console or a switch in the back edge of each door trim panel, accessable when the doors were open.

Seats were all new and available in three different forms. The base seat was an all cloth bucket with manual fore and aft adjustment plus for the first time on a Corvette, a back rest angle adjuster. The seatback was adjustable by pulling back on a lever on the forward side edge of the seat which relaxed the tension on a cable allowing movemnet. A six way power driver's seat was optional. The seats were of a premium design and featured a "wool pad comfort liner" and had integral head restraints. A leather covering was optional and had perforated centers with smoothe leather side bolsters.

The third seat style were the Cloth Adjustable Sport bucket (RPO AQ9) which featured motorized adjustable backrest "wings" and an electric inflatable lumbar support in the lower backrest. The manual backrest adjuster was swapped in favor of a power unit in the sport seats. The seats were finished in an aggressive, grippy cloth to help hold the driver in place.

In the C4, you stepped into the interior. When the center roof bar for the t-top was eliminated, the chassis lost substancial stiffness. To compensate, the side frame rails were raised quite hight to regain the lost strength. The engine was also set back a bit farther which made the interior a bit more crowded, especially in the footwell area. The center console was high and included the switch for the power mirrors and the overdrive switch for the optional 4+3 manual transmission. Also atop the console was a combination ashtray and cupholder. For the first time, there was storage in the lit and lockable console. In a move to clean up space in the console, the parking brake lever was moved to the left left frame rail by the driver's leg. Whne the parking brake was engaged, the lever would return to the floor rather than remain up as on traditional design.

The rear cargo area was larger at 17.9 cubic feet than the third generation cars, and was aided by the opening large opening rear window. The rear window was the largest piece of compound curve rear glass produced to date. Because the C4 was designed to have the rear glass open from the outset, integration into the vehicles structure was better served than in the 1982 Collector Edition. The rear area still had the latchable bins behind the driver's seat, with a little extra space gained by moving the battery from one of the wells to a placement at the right front gill panel. The roll out cargo shade operated much the same was as introduced on the 1978 restyle. The roof panel was stored in a built in holder that allowed it to rest above the floor allowing you to have room for cargo.

A 350 cubic inch small block (now RPO L83) continued to be standard in the C4, not the Wankel, a turbocharged V6 or some other exotic powerplant. With a less restrictive exhaust system the engine received a 5-hp bump over the 1982, now rated at 205. The engine continued to used the torque friendly "Cross Fire Injection" induction system. The engine was given a distinct modular look with the squared off magnesium air cleaner and similarly styled valve covers. An intake on each side of the air cleaner assembly received air from a set of ducts inder the hood that had rubber bellows that sealed the two together when closed. The traditional Corvette ignition shielding also had the cast magnesium appearance, however was made of plastic. The C4 engine has a cast iron crankshaft versus the forged steel unit that was last seen in the 1980 L82. Also missing from that same L82 was the four bolt main bearing caps. Because of the way the car was constructed, the engine along with the front suspension was loaded assembled from the bottom of the car during assembly. When equipped with the optional Z51 Performance Handling Package, a dedicated engine oil cooler was added, a feature that had never been factory installed before.

The transmission that backed the 205hp CFI 350 was GM's 700R4 4-speed automatic transmission with overdrive. The transmission also had a locking torque converter that essentially locked the engine and transmission together when travelling above about 37 mph. The converter would automatically disengage when downshifting to allow greater smootheness when accelerating. By locking the torque converter and eliminating the inherent slippage, greater efficieny and cooler transmission temperatures were achieved. For quick getaways, first gear in the transmission was a 3.06 to one; compare that to the 2.52 to one that the THM350 three speed automatic used. The base axle ratio was 3.07:1 while an optional 3.31:1 final drive was optional (but standard with the Z51 Performance Handling Package.)

The big news for C4 (other than the omission of a 1983 model year) was the return of the manual transmission. The new transmission, named 4+3 was a combination of a Borg-Warner T-10 four speed manual with a Doug Nash Engineering overdrive attached. This transmission was used to help Corvette achieve EPA numbers that kept it out of the "Gas Guzzler" tax arena. Chevrolet had offered the Borg Warner T5 five speed manual with overdrive behind the 305 cubic inch V8s in Camaros and Firebirds since 1983, but the torque of the 350 was deemed too strong. The T10 was a sturdy, proven transmission, and the Doug Nash overdrive unit had proven popular among the RV set, vehicles that are much heavier than three Corvettes together.

The transmission's clever +3 meant that when engaged, the powertrain module could place the vehicle in the overdrive mode when the condtions were right in gears two, three, and four. This meant a possible seven different gear ratios were possible. The overdrive was .67 to one which meant if the engine speed was 2000 rpm, in direct, the overdrive would knock that number down to 1340 rpm. If desired, the driver could choose to turn the overdrive off with a rocker switch mounted on the console. The transmission used a hydraulic slave cylinder to engage or disengage the clutch rather than heavy mechanical linkage of all previous Corvettes.

The rear differential was still an independent one, but had aluminum case rather than a cast iron unit on the C3. The ring gear diameter was now 7.875 inches. The ring gear diameter on C3's was 8.375 inches. The suspension used forged aluminum control arms to control the rear axle movement. The "fibreglass" leaf spring was actually a long group of wound glass fibres until the proper thickness and mass was reached, then the piece was impregnated with epoxy for durability. Shock absobers were Delco double acting with pliacell expansion bags. Later in the year, RPO FG3 Delco-Bilstein gas charged shocks joined the option list; 3,739 buyers opted for this $189.00 option. Rather than the three link suspension geometry of the C2 & C3, the C4 used a five link arrangement that helped keep reduce the camber changes during vertiical movement. A rear stabilizer bar of 20mm was standard.

At the front, beautiful, artlike forged aluminum A-arms were used and with the clamshell hood, there were in full display with the hood opened. Like the rear, a composite transverse leaf srring was used. The spring allowed for less mass, a lower center of gravity. and increased natural roll stiffness. the front spring rate was 431lbs/in, hower the rate increased by nearly 50% to 634lbs/in with RPO Z51. The rear spring saw a 22% increase with the base being 219 and the Z51 springs having a 262lb/inch rating. Two stabilizer bars were offered, a 24mm if equipped with the base suspension, of a 25mm with the Z51 Performance Handling Package.

Steering was changed from a recirculating ball setup to a more modern power assisted rack and pinion unit for a more positive steering feel. The base car had a fixed, but very quick 15.0:1 ratio, while this was changed an ultra quick, to a lane changing while sneezing 13.0:1 ratio with the Performance Handling Package. The quickness in the steering was reflected in the number of turns lock to lock, 2.36 turns for the base and an incredible less than two turn, 1.96 turns lock to lock for the Z51 cars.

Although the journalists loved the handing of the Z51 cars, this was however short lived when real world evaluations were encountered. The stiff, kidney busting ride of the Corvette was criticized and the car quickly went from hero to zero. The 1-g cornering ability on a skidpad had little credence driving the car on city streets.

In the planning stage, Corvette was to offer a pair of different wheel diameters were planned. The base wheel war to be a 15 x 7.0 in wide in the front, with the rears gaining a 1/2 inch in width. They were to be wrapped in a P215/65R-15 blackwall Goodyear Eagle GT radial, the same size as used on the Camaro Z28. Before production commenced, all ordered were required to include the 16-inch directional wheel. The wheels were 8.5-inches wide all around on base cars and the rears were an inch wider with RPO Z51. Being directional wheels, there were designed to rotate one way the aid in aerodynamics and brake cooling. A drawback to the design was the wheels couldn't be swapped right to left, nor could Z51 cars be swapped front to rear. If owners wished to rotate tires as part of routine maintenance, the tires would have to be dismounted from the wheels. For Z51 cars, there were four distinct wheels.

The tires mounted on the 16 inch wheels were also supplied by Goodyear, but they were the new Eagle VR50. This was a directional tire, designed to offer optimal grip and wet weather traction when traveling in the specified direction. The VR meant the tire was designed for a maximum sustained speed of 150 mph. The tires were sized P255/50VR-16, meaning the section width was over 12-inches wide. This allowed for a tire contact patch of nearly 10 inches. Goodyear was so enthused about the tires, that they ran a full page ad in Autoweek prior to the C4's intro, that these tires had helped the new Corvette achieve 1-g lateral acceleration.

Brakes for the new Corvette were supplied by Austrailain company Girlock. The brakes changed to a sliding caliper, and acted upon a 11.5" diameter rotors, front and rear. The calipers were made of aluminum, with nodular iron brackets, replacing the C3's troublesome cast iron calipers.

The ladder type frame of every Corvette since 1953 was finally replaced with a unitized frame on the C4. The chassis official name was "UniFrame", but this was quickly nicknamed to the "birdcage". Rather than using a fram that the body was cojoined to, the new chassis contained the baisc frame structure, the roof halo, and the windshield frame all in one integral piece. Individual body parts were attached to the frame, rather than a body that was completely bonded together. The frames were built up in the Bowling Green factory and was an all welded item. The assemby of the car was much more modular than the C3 with different components coming together, assembled as a unit, then installed in the car. The powertrain, complete with suspension was installed as a unit, lifted into place from beneath the assembled body/chassis.

The 1984 Corvette had a few problems, but the Corvette team tirelessly worked on them to build a better product, year after year. The long model run meant 51,547 1984 cars were built, the second best in Corvette history.

Total Production - 51,547
Model Number Description Production Base Price
1YY07 Corvette Sport Coupe 51,547 $21,800.00

Engine Codes
RPO Cu. In. Horsepower Torque Fuel System Trans Block Code Comp Ratio :1 Emissions
L83 350 205 @ 4300 290 @ 2800 2 X Single TBI Auto ZFC, ZFK 9.0 Fed
L83 350 205 @ 4300 290 @ 2800 2 X Single TBI Man ZFD, ZFL 9.0 Fed
L83 350 205 @ 4300 290 @ 2800 2 X Single TBI Auto ZFF, ZFM 9.0 Calif
L83 350 205 @ 4300 290 @ 2800 2 X Single TBI Man ZFN, ZFR 9.0 Calif
L83 350 205 @ 4300 290 @ 2800 2 X Single TBI Man ZFJ 9.0 Export
L83 350 205 @ 4300 290 @ 2800 2 X Single TBI ZFH 9.0 Export

Color & Trim Codes
Exterior Color Codes Interior Trim Codes
Color Code Color Code
Black 41U Bronze Leather AEE2 / 65C
Corvette Light Blue Metallic 20U Graphite Leather ABB2 / 122
Corvette Medium Blue Metallic 23U Gray Leather AQQ2 / 152
Corvette Dark Bronze Metallic 66U Dark Red Leather ARR2 / 742
Corvette Light Bronze Metallic 63U Saddle Leather AUU2 / 622
Corvette Gold Metallic 53U Blue Cloth HDD2 / 28C
Corvette Gray Metallic 18U Bronze Cloth AEE2 / 65V
Corvette Red 33U Graphite Cloth HBB2 / 12C
Corvette Silver Metallic 16U Gray Cloth HQQ2 / 15C
Corvette White 40U Saddle Cloth HHH2 / 62C
Light Corvette Blue Metallic /
Corvette Medium Blue Metallic
20U /
23M
Blue Cloth Sport Seats BDD8 / 28V
Corvette Light Bronze Metallic /
Corvette Dark Bronze Metallic
63U /
66M
Bronze Cloth Sport Seats BEE8 / 65V
Corvette Silver Metallic /
Corvette Gray Metallic
16U /
18M
Graphite Cloth Sport Seats BBB8 / 12V
Gray Cloth Sport Seats BQQ8 / 15V
Saddle Cloth Sport Seats BUU8 / 62V
Dimensions
Corvette Coupe
Overall Length 176.5
Height 46.7
Width 71.0
Wheel Base 96.2
Track F / R 59.6 / 60.4
Curb Weight 3192 Auto
3164 Man
Dimensions are in inches, weight in pounds unless otherwise noted.

1984 - A Brand New Corvette
1985 - Tuned Port Injection
1986 - The Roadster Returns
1987 - Sport Handling Arrives
1988 - Corvette Turns 35 and let the Corvette Challenge Begin!
1989 - Good-bye 4+3; Hello ZF 6-Speed
1990 - King of the Hill. Period.
1991 - A New Look
1992 - LT1 Returns
1993 - 40 Years of Corvette in Ruby Red
1994 - Brand New Inside
1995 - The King is Dead, Long Live the King!
1996 - End of an Era, Grand Sports and Collectors

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