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The First "Mid Year" Corvette - 1963
Corvette's designers and engineers -- Ed Cole, Zora
Arkus-Duntov, Bill Mitchell and others -- knew that after 10 years in its basic
form, albeit much improved, it was time to move on. By decade's end, the
machinery would be put into motion to fashion a fitting successor to debut for
the 1963 model year. After years of tinkering with the basic package, Bill
Mitchell and his crew would finally break the mold of Earl's original design
once and for all. He would dub the Corvette’s second generation "Sting
Ray" after the earlier race car of the same name (but now spelled out in
separate words).

The 1963 Corvette Sting Ray debuted with a trimmer 98-inch
wheelbase and first-time all-independent suspension.
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The independent rear suspension Duntov created for Sting Ray
was simple yet effective. It was essentially a frame-mounted differential with
U-jointed half-shafts tied together by a transverse leaf spring -- a design
derived from the CERV I concept. Rubber-cushioned struts carried the
differential, which reduced ride harshness while improving tire adhesion,
especially on rougher roads. The transverse spring was bolted to the rear of
the differential case. A control arm extended laterally and slightly forward
from each side of the case to a hub carrier, with a trailing radius rod mounted
behind it. The half-shafts functioned like upper control arms. The lower arms
controlled vertical wheel motion, while the trailing rods took care of fore/aft
wheel motion and transferred braking torque to the frame. Shock absorbers were
conventional twin-tube units.
Considerably lighter than the old solid axle, the new rear
suspension array delivered a significant reduction in unsprung weight, which
was important since the 1963 model would retain the previous generation's
outboard rear brakes.
The new model's front suspension would be much as before,
with unequal-length upper and lower A-arms on coil springs concentric with the
shocks, plus a standard anti-roll bar. Steering remained the conventional
recirculating-ball design, but it was geared at a higher 19.6:1 overall ratio
(previously 21.0:1). Bolted to the frame rail at one end and to the relay rod
at the other was a new hydraulic steering damper (essentially a shock
absorber), which helped soak up bumps before they reached the steering wheel.
What's more, hydraulically assisted steering would be offered as optional
equipment for the first time on a Corvette -- except on cars with the two most
powerful engines -- and offer a faster 17.1:1 ratio, which reduced lock-to-lock
turns from 3.4 to just 2.9.
The Development of the Sting Ray
The production Sting Ray's lineage can be traced to two
separate GM projects: the Q-Corvette, and perhaps more directly, Mitchell's
racing Stingray.
 This "design heritage" photo was released to herald the 1963 Corvette Sting Ray. The Stingray racer and 1960 XP-700 show car front the new convertible and fastback.
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The Q-Corvette, initiated in 1957, envisioned a smaller,
more advanced Corvette as a coupe-only model, boasting a rear transaxle,
independent rear suspension, and four-wheel disc brakes, with the rear brakes
mounted inboard. Exterior styling was purposeful, with peaked fenders, a long
nose, and a short, bobbed tail. The car was originally envisioned as one of a
full line of large rear-transmission cars with which the Q-Corvette would share
major components. But the passenger-car line was scrapped as being too radical,
and the Corvette variant suffered the same fate.
Meanwhile, Zora Arkus-Duntov and other GM engineers had
become fascinated with mid- and rear-engine designs. It was during the
Corvair's development that Duntov took the mid/rear-engine layout to its limits
in the CERV I concept. The Chevrolet Experimental Research Vehicle was a
lightweight, open-wheel single-seat racer. A rear-engined Corvette was briefly
considered during 1958-60, progressing as far as a full-scale mock-up designed
around the Corvair's entire rear-mounted power package, including its
complicated air-cooled flat-six as an alternative to the Corvette's usual
water-cooled V-8.
By the fall of 1959, elements of the Q-Corvette and the
Stingray Special racer would be incorporated into experimental project XP-720,
which was the design program that led directly to the production 1963 Corvette
Sting Ray. The XP-720 sought to deliver improved passenger accommodation, more
luggage space, and superior ride and handling over previous Corvettes.
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