The C3 Corvette was an unqualified success. The public had accepted
the new body style and responded by pushing sales volume to the 40,000 / year level in six of the last seven years of production.
The Corvette had established itself as the technological flagship of the GM lineup. But the last significantly new Corvette
chassis was introduced in 1963, more than 20 years earlier. To stay on top, a new generation Corvette was needed.
Chevrolet had been teasing car enthusiasts throughout the '80s with
all sorts of exotic Corvette prototypes and show cars. Radical design features included rotary engines, mid-engine drivetrain
layouts and even gullwing doors. The rotary engines had fuel economy woes and other technical issues and the mid-engine Corvettes
presented storage space problems. David McLellan was the new Corvette Chief Engineer and he brought with him solid engineering
sensibilities. The decisions regarding the new Corvette were his and when the new generation was finally introduced to the
public, a conservative direction was taken. The C4 Corvette featured a front engine V8, the same layout since 1955.
The new C4 was penned by Design Chief Jerry Palmer. The goal was
to keep the Corvette identity, which they did. The new car was unmistakably a Corvette. The rear view actually was similar
to the 1968 - 1973 models as opposed to the 1974 and later years when the federally mandated bumper protruded outward. Technology
had advanced over the ten years the regulations were in effect and designers were in a better position to design what they
wanted. The four round tail lights - a significant Corvette styling cue - were still prominent.
One styling cue that disappeared was the "Coke Bottle" effect of
the C3 Corvettes. This refers to the pinched in passenger area, similar to the shape of the classic Coke bottle. It looked
awesome but many complained of a too limited interior space. Smoothing the sides gave a whopping 6½ inches more shoulder room.
Much of the extra interior room went towards a larger center console.
The area below the center tunnel was used to route exhaust plumbing, driveshaft, catalytic convertor, etc. This meant that
the floor could be lowered by two inches. Ground clearance was 5¼ inches (¼ inch more than the C3) so the designers were able
to incorporate more headroom along with lowering the roofline by about an inch, which improved aerodynamics. The overall length
was 8½ inches less than the C3.
The T-tops of the C3 generation were replaced by a full Targa roof
for the C4. This presented a challenge to the chassis engineers as the Targa configuration has a inherent chassis rigidity
disadvantage. Owners did get a more open feeling with the roof removed and as with the T-tops, they also had the security,
safety and weather sealing advantages of a coupe. When not in use the top was stowed in the luggage area and did cut down
on available storage space. A high door sill was designed in to help compensate for the loss of structural strength inherent
with the Targa roof.
The very useful hatchback opening that was first seen on the 1982
Collector Edition Corvette became a part of all C4 Corvettes. Engine access was improved in 1984 with a "clamshell" hood design
that also allowed for suspension and wheel access. It was similar to the setup found on the Corvette's sports car brethren
such as the Jaguar E-Type and the Ferrari Boxer.
The 1984 engine was essentially the same as installed in the 1982
'vette. An epoxy coated magnesium air cleaner cover was designed for a similar look as the suspension pieces which were also
visible when the hood was opened.
Also carried over from the 1982 engine was the Cross-Fire Injection
system, as proudly noted on the air cleaner cover and body side molding.
Initially all C4 Corvettes
came with an automatic transmission, the same four speed that was first introduced in 1982. Later in the production run (January
1984) a Borg-Warner T-10 four speed manual transmission was available. The options list gave buyers their choice of transmission
with no extra cost for either. The manual featured an overdrive unit between the transmission and the driveshaft and would
engage in gears two, three and four. In theory at least this gave the Corvette a seven speed transmission. The overdrive was
set up to to engage during normal street driving but with spirited driving only the four normal gears were employed. A console
mounted switch could also turn the overdrive off.
The two personalities engineered into the C4 had a purpose. CAFE (Corporate Average Fuel Economy) EPA
rules were in effect at the time as was a gas guzzler tax. Cars that did not get an EPA fuel economy rating of 16.0 mpg were
subject to the extra cost as well as a social stigma. This was another area where Corvette engineers took a stand. By engineering
the car to behave differently when driven mildly (which is how the EPA tested the cars) mpg figures just beyond gas guzzler
ratings levels were possible. It is worth noting that no Corvette has been subject to the gas guzzler tax, a point of pride
for its engineering staff.
A front grill, which
had gradually been disappearing as the Corvette progressed, was gone completely in the C4. Some judicious engineering resulted
in adequate airflow ducted from under the car for the radiator to cool the engine. Replacing the grill was a set of halogen
running lamps, an inspiration gained from comparisons to the Porsche 928 and other european cars of the time. Cornering lamps
located behind the front side marker lights were standard.
Note also that the new Corvette had almost a "bumperless" design. Although functional in that the bumpers
protected the car from up to 5 mph of harm, they were also integrated fully into the body shape so that it was not possible
to point out where the bumpers/body were defined.
Light weight was a primary
engineering goal which was achieved with generous amounts of aluminum in the suspension and chassis parts. Aluminum alloy
was used in the half shafts, differential support, front and rear suspension crossmembers, drive shaft, torque convertor /
transmission housing and various mounting brackets. The use of light weight materials in suspension parts was used to reduce
unsprung weight which is necessary in a good handling world class sports car. Other benefits include more consistent parts
with a die cast process, freedom from rust and they just look awesome.
A U-shaped stamped aluminum channel beam connected the transmission and the differential. Firmly tying
together the major front (engine/transmission) and rear (differential and rear suspension) components improved handling and
makes for a tight and agile driving feel. It's a common method used in other quality handling cars, such as the Mazda Miata.
The transverse leaf
spring which had worked so well in the rear suspension of all Corvettes since 1963 was part of the C4 design for both the
rear and front suspension. A new design was made up of a single leaf (as opposed to multiple leafs) using fiberglass reinforced
epoxy resin plastic. The innovative system resulted in lower unsprung weight and increased reliability. According to Chevrolet,
the new fiberglass springs could be exercised 5,000,000 times without failure while the steel equivalent would usually break
after about 750,000 jounces.
The C2 and C3 rear suspension, although fully independent, was still a relatively simple three link design.
The C4 got a bit more sophisticated with a five link rear suspension.
At the front suspension, another Corvette first appeared: rack and
pinion steering. It was the same system used in other great sports cars and was known for quick response and accuracy. A small
damper was added to improve steering feel. The standard ratio was a relatively quick 15.5:1; an even faster ratio (13.0:1)
was part of the performance handling package (RPO Z51; $600.20).
Handling was one of
the primary goals during the development of the C4. Corvette engineers were obsessed with it. All the usual methods for making
the Corvette the best handling car available were tried and a few new ones were developed.
Selecting the right tire is very important if the best handling is desired. Goodyear stepped up to the
plate with a special tire designed just for the Corvette. The specifications were tough: reasonably quiet, good in wet weather,
safe at a top speed of 145 mph, crisp handling feel and a life span of at least 10,000 miles even with enthusiastic driving.
Goodyear used knowledge gained from Formula One racing to meet and even exceed these demands with the VR50 "Gatorback" tires.
They were mounted on special 16 inch rims, also a Corvette exclusive. The RPO Z51 equipped cars featured 8.5 inch wide wheels
in front and 9.5 inch wheels in the rear. Both the tires and wheels were directional meaning that they were designed to roll
in only one direction. Since the front and rear wheels were of different size, a given wheel could only be mounted on one
corner of the car. Modular wheels were popular at the time especially on European sourced cars. But they had an aerodynamic
disadvantage with their surface close to the brake, so a design that was flush to the body surface was chosen.
One common technique for improving handling is to specify very stiff
springs and/or shock absorbers. This was done on the standard Corvette and the optional Performance Handling Package (RPO
Z51; $600.20) was equipped with even stiffer springs and German made Bilstein shock absorbers. As is often the case, there
can be too much of a good thing and the 1984 Corvette is an excellent example. The Corvette had outstanding handling but a
steep price was paid in the form of reduced ride quality. Terms such as "teeth rattling" "bone jarring" and "brain scrambling"
were often used by passengers and drivers alike, many of which were not used to performance suspensions.
Besides tormenting its
occupants, the very stiff suspension also tortured the new Corvette body. Squeaks and rattles throughout the structure became
common and so did complaints to the quality people at Chevrolet.
One of the problems was with the Z51 suspension and the fact that many who ordered it did not know what
they were getting in to. Despite its high price nearly half of the 1984 production was Z51 equipped. Although it was a good
idea for racetracks (which are typically billiard-table smooth) it had no place in the real world of potholes and speed bumps.
One of the ways handling is measured is known as "g force". "G"
in this case is short for gravity. It is measured by driving the car around a 100 or 200 foot diameter circle (called a skidpad)
and measuring the maximum lateral force it can generate without going out of control. Most standard issue passenger cars will
measure about .70g. In 1984, the best handling performance cars would generate approximately .85g. When tested by the magazines,
the C4 (with the Z51 performance suspension) generated around .90g, a very respectable figure. Using special suspension settings
not advisable for everyday use, Corvette engineers were able to get an amazing 1.01g!
No detail was overlooked when it came to making the 1984 Corvette
the best ever. The C3 had featured hide-away headlights, but they were a flip up design, so the top of the headlight was the
same whether it was up or down. The C4 differed in that its hidden headlight rotated when activated. so in effect the top
became the bottom. The result was that a very un-aerodynamic lip present in the functioning C3 light package was a nicely
smoothed and aerodynamically friendly edge in the C4.
The interior of the C4 was all new and like the chassis, incorporated
some innovative features. There was a fair amount of room especially when compared to the C3, although the driver and passenger
did feel isolated by the prominent center tunnel. Rather obvious for the passenger is the large lump thing called the "breadloaf"
because of its shape. At the time it was anticipated that federal regulations would include a safety impact for the passenger,
not unlike the collapsible steering column in front of the driver. The breadloaf was designed to meet this requirement which
ultimately did not materialize.
Cloth seats were standard and leather was an option (RPO A09; $400.00).
Cloth sports seats (RPO AQ9; $625.00) were available later in the model year and included an adjustable lumbar support and
The instrument panel was all electronic and advanced for 1984. Both
the speedometer and tachometer consisted of bar graphs in addition to numerical readouts. This was especially useful with
the tachometer as the graph took on the shape of the power engine's power curve. The idea was that the driver could quickly
determine if they were using engine revs in the desired area of the power band. The whole panel was quite colorful and in
the words of one enthusiast, "looked like the lights of Tokyo".
The speedometer graph only went up to 85 mph, in accordance with
government regulations of the time. Oddly enough, the numerical readout was not similarly limited. A fair amount of information
was available, including fuel level, oil pressure, oil and coolant temperature, and battery voltage. A computer calculated
and presented instant and average miles per gallon as well as fuel range figures. A switch setting determined if the oil pressure,
oil and coolant temperature, odometer, speedometer readings were metric or English units. It was however a complicated affair
with reliability problems; reports indicate that many instrument panels had to be replaced at considerable cost.
In the 1980s customers of just about all cars were removing the
factory sound system and installing better performing aftermarket units. Chevrolet answered the challenge with a partnership
with Bose, a well respected home audio manufacturer. The Delco-Bose (RPO UU8; $895.00) unit was custom designed for the C4
Corvette and featured innovations such as amplifiers at each of the four speaker locations, a noise reduction system for both
the radio and cassette tapes, true electronic tuning and speaker enclosures designed for the Corvette interior. Everyone agreed
that the system produced excellent sound and despite the high price was installed on the majority of 1984 Corvettes.