Dave Hill Strikes Again ... Superior C6 Chassis
60 VETTE 19.0 4
orvette fans have been
frustrated for years with
Chevrolet’s evolutionary
Corvettes. The “pie-in-the-
sky” mid-engine Corvette
has been around since the 1960s and any-
thing less was evolutionary. The pending
C8 aside, the C5 was the most revolution-
ary Corvette; because of the hydroformed
steel perimeter frame, center backbone,
all-aluminum LS1 fuel-injected engine
and transaxle. The C5 was the most solid
Corvette ever offered and allowed engi-
neers to vastly improve the basic suspen-
sion, the Z51 and the Z06. The racing C5-R
won its class at Daytona in 2001 and 2003;
won its class at Sebring in 2002, 2003 and
2004, and won its class at Le Mans in 2001,
2002 and 2004. This never would have
happened without the superior, basic C5
chassis. Dave Hill’s team got the C5’s chas-
sis design so right that by 1999 they deter-
mined that a C6 needed to be started.
Whereas the C5 structure was revolu-
tionary, the C6 was evolutionary. While
the C6 chassis is different from the C5, it
is essentially the same hydroformed steel
perimeter frame with a center backbone,
with the engine, torque tube and trans-
axle all as stress members of the overall
structure.
Let’s start with the basic C6 chassis. The
chassis has a 1.2-inch longer wheelbase
of 105.7 inches, but the overall length is
5.1 inches shorter than the C5 chassis. To
achieve this, engineers shortened the
framerails 2.4 inches and changed the
tube-formed front bumper beam to a unit
made with two channels welded together
to save 0.6-inch. Between the shorter
frame and less overhang on the body, the
C6 had a total reduction of 5.1 inches of
length on the C5. The shorter frame also
increased the torsional stiffness. And to
reduce squeaks, rattles and vibrations,
high-strength steel braces were added to
the frame to improve structural rigidity.
BY SCOTT TEETERS (^) I ILLUSTRATIONS BY THE AUTHOR (^) I PHOTOGRAPHY BY GM ARCHIVES
THE ILLUSTRATED CORVETTE
Designer Series No. 262
Weight savings were picked up by using
extruded aluminum beams in the interior
instead of the cast-aluminum beams from
the C5. The instrument panel has additional
brackets for the beam under the dash-
board. Side-impact beams were made of
aluminum and saved 4.5 pounds, and the
doors have electronic latch and lock mech-
anisms instead of mechanical mechanisms.
Aluminum braces were used throughout
the structure to improve crash perfor-
mance. The skid-bar in front of the radia-
tor is also aluminum. An aluminum panel
that saved 1 pound and increased stiffness
replaced the steel driveline panel under the
driveline torque tube. To increase upper
rigidity, the windshield frame has extra
gussets. And the trunk uses lightweight
plastic braces.
Corvette systems engineer Ed Moss said,
“We are making it (the C6) smaller, lighter
but stiffer.”
The issue of stiffness in high-powered
sports cars with wide tires cannot be under-
estimated. Increased grip, torque and
horsepower will put tremendous added
stress to a performance car’s structure.
Imagine what would happen if an LT5
engine and big tires were applied to a stock
C1 chassis. The C5 1999-’00 Corvette hard-
top, with its bolted and bonded hardtop
increased the overall structural stiffness by
12 percent, enough to make it an excellent
base to build the Z06 upon. The basic C6
platform offered a significant improvement
in stiffness that made it an excellent plat-
form to build the Grand Sport that used Z06
suspension parts and wide tires. Without
any increase in power, the Grand Sport was
a better Corvette. Stiffness matters.
While the C6’s suspension is similar to
the C5’s, there are no carryover parts. The
basic design of the short-long A-arms, trans-
verse composite leaf springs independent
suspension is the same. The control arms,
springs, dampers, bushings, sway bars
and steering gear are all completely rede-
signed. New hub knuckles and dampers
allow for greater suspension travel thanks
to improved clearance. One issue with C5s
was road noise and twitchiness on rough
roads. To improve handling and ride, steer-
ing geometry and the progressive rates of
the composite springs were improved.
Like the C5, the C6 offered customers
three levels of suspension performance.