"We knew we wanted a front-engine car that
had to be ultra-compact and lightweight, yet robust enough to handle
605 horsepower," said Theodore. "There was nothing that
fit the bill on first glance."
But Rumpel’s team saw a creative solution.
"We were already planning to use the Ford
GT suspension systems, and we asked ourselves how much more of the
GT we could borrow," he said.
Quite a lot, as it turns out. Even though the
GT is a mid-rear-engine car, and the proposed roadster was to have
a front engine, a decision to mount the transmission at the rear
made the connection.
"Once we really started looking into it,
we had an epiphany," Theodore said. "The project took
on a new sense of purpose when we really started leveraging the
Ford GT engineering."
The team worked long hours with John Coletti,
head of Ford’s Special Vehicle Team, to maximize the commonality.
Fresh from completing the all-new Ford GT in just 15 months, Coletti
understood what it took to build fast cars faster than ever. "It
was a great team effort," Coletti said.
The bulk of the rear structure is made from
slightly modified Ford GT components, including the massive, trellis-like
cast aluminum suspension nodes, the rear rails and bumper beam,
a major cross-member and the brackets used to mount the transmission.
The center portion of the space frame also has
a high degree of GT commonality–major aluminum extrusions
are based heavily on existing pieces. At the front of the roadster,
the team incorporated the extruded main rails, steering rack cross-member,
crash-management sections and the bumper beam.
"The concept car was even assembled using
the prototype jigs the GT team no longer needed," said Rumpel.
"This commonality and re-use goes hand-in-hand with our speed
and cost efficiency."
Overall, the Ford Shelby Cobra concept is more
than 2 feet shorter than the GT, with a wheelbase nearly 7 inches
shorter. Even the track width has been reduced by more than an inch.
That the concept car and the GT share any parts at all is a testimony
to the flexibility of the space frame design and the creativity
of the chassis team.
Ford GT Suspension, Steering and Brakes
To attach the massive 18- and 19-inch wheels
and tires to the car, the team chose to use the Ford GT suspension
system with a few modifications to accommodate the increased weight
up front. Like engine technology and electronics, suspension design
has come a long way in more than 40 years.
"The original leaf-sprung Cobras were awesome
on the straightaway but didn’t make a name for themselves
in the turns," said Rumpel.
Theodore was even more direct, "The original
427 was a beast."
The new Ford GT earns praise for its combination
of agility, grip and easy-to-drive character, a reflection of its
sophisticated suspension design and the expertise of its chassis
engineers. The Ford Shelby Cobra concept applies the best of the
GT suspension to a big-engine roadster.
A double-wishbone suspension design with unequal-length
aluminum control arms, coil-over monotube shocks and stabilizer
bars is used front and rear. The upper control arms are identical
at all four wheels and are made with an advanced rheo-cast process
that allows the complexity of form associated with casting, yet
retaining the strength of forging. The metal, heated to just below
its melting point, is the consistency of butter when it is injected
into a mold at high pressure. Pressure is maintained as the part
cures, preventing porosity in the final product for exceptional
The steering rack also is borrowed from the
Ford GT, with a few modifications. The steering column, like the
Ford GT’s, draws on Ford engineering best-practices like the
low friction, high stiffness and light weight that have made the
Ford Focus steering column among the best in the industry. Braces
between the front shock towers and below the isolated engine mounts
improve torsional rigidity and aid steering response.
With more than 600 horsepower available at the
throttle pedal, the brake pedal had to be equally potent. The team
set braking distance targets comparable with today’s best
sports cars, and turned to the Ford GT braking system for suitable
Brembo "monoblock" one-piece aluminum
brake calipers with four pistons each grab cross-drilled, vented
discs at all four wheels. The discs are a massive 14 inches in front
and 13.2 inches in the rear, for fade-free stopping power. But the
team stopped short of fitting the car with an antilock braking system,
in keeping with its racing character. Brake balance is biased slightly
to the front wheels to aid stability.
For packaging reasons, the team devised a novel
offset actuation linkage for the brake booster and master cylinder,
so the brake pedal can be placed in a normal position even though
its hardware is off to the side of the engine bay.
The one-piece BBS wheels are wrapped by BF Goodrich
Z-rated racing slicks, size 275/40R18 in front and 345/35R19 in