Corvette C2 1963-1967 Mid-Years
The 1963 "Sting Ray" coupe, designed by Bill Mitchell's group including Peter Brock
and Larry Shinoda has a spine in the rear window splitting it in two. The striking
design was opposed by Zora Arkus-Duntov because it limited rear visibility. Zora
had been instrumental in making the 1963 a much better engineered car including
independent rear suspension and disc brakes. Mitchell threatened to go back to the
old design if the split window was not kept. Many of the engineering innovations
came from the Q-Corvette project, Mitchell's "Sting Ray" race car and the CERV 1
which was a pet project o Zora's that was designed around the Indy car dimensions.
The Chevrolet code name for the new Sting Ray was the XP-720. Mitchell was so excited
about the coupe that he had to be told by the board to create a convertible. Zora
hated the name Sting Ray saying "It's a dumb fish!" but Bill Mitchell loved the
name and it stuck.
The center of gravity was dropped over 2 inches by using a ladder type frame instead
of the x-frame that had been used previously. This new frame allowed the passengers
to sit inside of the frame instead of on top of it. It uses a ladder with 5 crossmembers
and is 4 inches shorter than the 1962 frame. The new coupe frame is 90% stiffer
than the 1962 model. The convertible didn't fare as well and is only 10% stiffer.
This frame, basically unchanged would be used until 1982.
Zora wanted the new Corvette to have independent rear suspension (IRS) and thought
they could use technology from the Q-Corvette and Q-sedan projects. Unfortunately
the development costs that could have been absorbed by the passenger car project
were not because the program had been cancelled. Zora came up with another plan,
he told the bean-counters that with an independent rear suspension, he could sell
30,000 Corvettes even though he knew most drivers couldn't tell the difference.
The racers were the ones that would notice and Zora had always thought of the Corvette
as a racing chassis. The new IRS that was designed used a system that was common
on race cars of the time. Using a simpler system that used the driveshafts as a
part of the suspension, they were able to create a suspension that was cheaper than
the European cars and lighter than the old solid axle system. The system uses a
transverse nine leaf spring, this is a single spring that is mounted across the
car from one wheel to the other. The reason for this spring arrangement was the
lack of room for coil springs and the weight savings.
The new "Sting Ray" included a power steering option on all but the most powerful
optional engines. The steering ratio was also faster reducing the turns from lock
to lock from 3.4 to 2.9. Power assisted brakes were also available although they
were still drum brakes because money for developing disc brakes was not available.
Optional finned aluminum drums and sintered metallic pads could be ordered to increase
stopping ability and decrease brake fade under hard braking.
Designers moved the engine one inch to the left to increase the amount of foot room
for the driver. This also had the opposite affect on the passenger foot room. The
luggage area was designed to be fairly large but the designers ran out of money
before a working trunk lid could be added. This requires luggage to be loaded through
the cabin over the seat backs. The steering column is adjustable by 3 inches, unfortunately
the adjustment can only be made from under the hood with a wrench.
Engines were still based on the 327 used in 1962, it could be mated to a 3 or 4
speed automatic or the Powerglide automatic. A supercharged engine was built for
Bill Mitchell's show car, code named XP-755 but it was never seriously considered
for production. During the 1963 production the Borg-Warner 4-speed transmissions
were replaced with 4-speeds from the Muncie, Indiana plant.
During the development of the C2, GM had been operating under a total ban on racing
sanctioned by the AMA. Zora knew that no matter what GM did people would race Corvettes,
he pushed for more options that were racing oriented. Ford was back in the racing
game with their "Total Performance" program in 1962 and Zora wanted Corvette to
be there. They came up with an option package to help racers along. RPO Z06 "Special
Performance Equipment" included larger diameter shocks a 20% larger anti-roll bar
in the front and springs nearly twice as stiff as stock. It also included power
brakes with dual master-cylinders, the aluminum finned drums and new air scoops
designed to cool the drums, sintered metallic linings were also included. For power
a 360 horsepower 327 paired with the M21 four-speed transmission was part of the
package. Also included was posi-traction, cast-aluminum knock-of wheels and a larger
36.5 gallon gas tank. Because of the size of the gas tank the option was only available
on the coupe. Later in the model year problems with the aluminum wheels were discovered,
they leaked air through the porous aluminum. This caused them to be deleted from
the Z06 option, along with this the oversized fuel tank was also removed. This allowed
RPO Z06 to be ordered on convertibles. Only 199 Z06 optioned Corvettes were produced,
all of them with the Borg-Warner 4-speed. Interestingly 75 of these came with radios
installed, possibly not intended for the race track.
25 Pilot cars were built by June of 1962. These cars were built to get the bugs
out of the manufacturing process and also to give the magazines time to do a story
that could be published at the same time the car was released to the public. The
magazines loved the car and so did the buyers. By the end of 1963, Chevrolet had
doubled the shifts at the St. Louis plant and built 21,513 Vettes, more than double
the number of 1962 Covettes produced. Zora was quoted as saying "For the first time
I now have a Corvette I can be proud to drive in Europe."
The first race that the new Z06 optioned Corvettes raced in was the Los Angeles
Times Three-Hour Invitational Race held in Riverside California on October 13th,
1962. A total of four Corvettes entered the race. Three Corvette Z06's were prepared
for the A-production race under the supervision of Zora Arkus-Duntov. These cars
were driven by Bob Bondurant, Dave MacDonald and Jerry Grant. One car that had arrived
earlier was entered by Mickey Thompson was driven by Doug Hooper. Another car entered
in the race was the new Shelby Cobra. Shelby had wanted to buy Corvettes without
the body and Chevrolet wouldn't sell them to him. After being snubbed by Chevy,
Carrol Shelby went to Ford and they gave him engines and help, he took the engines
and put them into an English AC Ace and named it the Cobra. At the beginning of
the first hour of the race one of the Corvettes and the Cobra had broken down. By
the end of the second hour two more of the Corvettes were out. At the end of the
race the Covette driven by Doug Hooper won the race!
For the 1964 production year Bill Mitchell agreed to drop the spine in the rear
window. During design and engineering of the 1963 model the spine had to be widened
much more than Mitchell had wanted. New progressive rate front springs and revised
shock valving were added to improve handling without affecting ride too much. The
coupe had a fan added in the rear compartment to alleviate a heat problem caused
by the large back glass on sunny days. A new Holley 4150 carburetor added 25 horsepower
to the solid lifter engine. The fuel-injected version got a new intake manifold
increasing its output to 375 horsepower.
Much effort was made to tame the mechanical and road noise of the '63 Vette. New
insulation was added, the transmission and engine mounts were revised. Zora wanted
the car to be a true sports car and didn't think the changes were necessary but
he realized the customers who bought the car drove them on the steet as well as
at the race track. Another record year for Corvette production with 22,229 cars
produced, 8,304 coupes and 13,925 convertibles.
The early 1960s started the muscle car era. Chrysler started the trend with their
Hemi powered sedans which were cheap and fast. Pontiac came out with the GTO and
Torino cars that were also cheaper than the Vette and had more horsepower. This
chain of events eventually pushed the Corvette to the Big Block as well so it could
compete horsepower to horsepower. Zora prefered the small block due to it's power
to weight ratio and how the car handled with it but in order to compete, marketing
decided Corvette needed a big-block.
More to come...