For the all-new Shelby GT350R,
the most track-ready road-going production Mustang ever, Ford dreamed of using
the ultimate high-performance material for its unique wheels – carbon fibre.
Carbon fibre wheels are not entirely new. It’s available in the automotive
aftermarket and the low-volume supercar manufacturer Koenigsegg have offered
carbon fibre wheels. But Ford and its Australian supplier Carbon Revolution
took on the challenge of crafting the first mass-produced, track-capable carbon
fibre wheels as standard equipment for Shelby GT350R.
Designed, developed and tested
with the highest of quality standards in mind, these first-of-a-kind wheels
deliver unprecedented chassis performance, massive weight savings and improved
driving dynamics.
According to a Ford press
release, in early testing with benchmark vehicles, prototype wheels showed
significant potential – improving suspension response times, chassis dynamics,
steering feel and ride quality. When the decision was made to pursue this
technology for use in a production vehicle, the engineering team was challenged
to develop a wheel that met Ford’s strict standards for durability, quality,
craftsmanship and premium finish.
But why carbon fibre? Among
sports car enthusiasts, carbon fibre wheels are on the short list of dream
components for high-performance vehicles. In the rarefied world of supercars
only Koenigsegg has offered optional carbon fibre wheels.
Lowering overall curb weight in
general is beneficial to a car’s dynamics, but a reduction in unsprung weight
(those components not supported by the suspension) can have a significant
impact on handling and performance. Less unsprung weight helps vehicles start,
stop and turn faster by reducing wheel rotational inertia, dramatically
improving response time to driver input. Lower unsprung weight also translates
to suspension components not having to work so hard to keep the tyres in
contact with the road over undulating or broken surfaces.
Although Carbon Revolution has
been the leading manufacturer of carbon fibre wheels, both Ford and the
supplier recognised significant innovation was needed to meet Shelby GT350R
programme needs. This project would set the standard for mass-produced carbon
fibre wheels.
Ford wheels must endure tests
that include curb strikes, UV and chemical exposure, and extreme heat
durability testing. The GT350R wheels would need to fulfill all of these
demands in order to proceed to production.
A common misconception of
carbon fibre is that while it’s strong, it’s also a brittle material. Some
formulations may have this characteristic, but carbon fibre’s durability is a
feature of the type of resin and design intent of the part. The wheels of
Shelby GT350R are designed to be stiff, light and resilient.
One of the most severe tests
for wheels in the Ford development process involves striking a curb at speed –
a test that, without proper design, can cause serious wheel and tire damage.
Because of the light weight, advanced construction methods and resins in the
wheels, along with the highly-developed MagneRide dampers, the suspension was
able to react so fast that the driver wasn’t sure the test had been carried out
correctly and ran it twice to be sure. The suspension response was fast enough
to greatly diminished the severity of the impact – that’s the power of
minimizing unsprung weight.
During track testing the
extreme performance capabilities of the braking system developed heat which
required the maximum technology available from Carbon Revolution. When brake
temperature measurements were taken, it was revealed Shelby GT350R’s
ultra-powerful brakes were creating rotor temperatures in excess of 900 degrees
Celsius. As a result, the wheel design was elevated from a road car
specification to a thermal standard more suitable for motorsports.
For decades aerospace
companies have treated turbine blade materials subject to extreme heat with
ceramic coatings to help improve durability. The technology is also used in
top-tier open-wheel racing environments. A thermal barrier coating system
developed by Carbon Revolution uses this same technology.
Created specifically for
motorsport and aerospace applications where extreme temperature conditions are
encountered, Carbon Revolution’s thermal barrier coating system uses a
multistage, multimaterial coating formulation that provides an excellent
thermal barrier. Using a plasma arc gun to liquefy a ceramic material, the
wheels are coated at critical points around the inner wheel “barrel” and on the
back of the spokes. The result is an incredibly thin, nearly diamond-hard
coating that reliably shields the resin from heat – reducing maximum wheel
temperatures and allowing continuous track use by even the most aggressive
drivers.
But that’s not the end of the
story with regard to testing. Upon extreme exposure to harsh UV environments,
corrosive salts and road chemicals, it became apparent that to achieve the
durability required by Ford, a special coating would need to be developed to
protect the resin from the environment.
Carbon fibre parts are
notoriously challenging when it comes to delivering a flawlessly smooth painted
surface – the kind of finish Ford demands for all of its vehicles. Several
proprietary new processes were developed that resulted in a robust, high-gloss
black finish that not only looks good, but ensures a long life for the wheels.
Manufacturing carbon fibre
wheels begins with the creation of the preformed internal carbon structure,
composed of precisely manufactured carbon strands arrayed into woven fabrics.
The elements are then placed into a mold using state of the art manufacturing
techniques.
An RFID chip with a unique
tracking number is embedded in this structure, and each wheel is individually
entered into a quality assurance system. Once this structure is assembled, it’s
infused with resin and cured at high temperatures.
This process results in a
one-piece wheel that ensures maximum strength – eliminating the need to bond or
glue the wheel’s spokes and barrel components together.
As the wheel cures, 61
individual checks and more than 246,000 data points are logged before it’s
released from the machine. To guarantee quality parts, the cured wheels are
analyzed using a 3D computerized tomography (CT) imaging process in which more
than 18,000 X-ray images are taken. If the wheel passes inspection, it
undergoes machining for the valve stem and mounting hardware holes before it
gets painted, coated, assembled, dimensionally checked and shipped to Flat Rock
Assembly Plant for installation on a new Shelby GT350R Mustang.
That the new Ford Shelby
GT350R Mustang will be rocketship-fast should come as no surprise, but by
cutting the weight of each wheel nearly in half compared to an equivalent
aluminum wheel (18 pounds versus 33 pounds), handling and acceleration
performance see serious benefits. The wheels also provide a reduction in
rotational inertia of more than 40 percent, which positively impacts
acceleration and braking performance. The wheels are so light, the springs and
MagneRide dampers had to be recalibrated because the suspension can respond
considerably faster to road inputs.
“The GT350R wheels and tyres
were developed to be the most track-capable parts we’ve ever produced,” said
Adam Wirth, chassis supervisor, Ford Performance, adding that “The carbon fibre
wheels reduce vehicle weight by 60 pounds compared to aluminum, yet are stiffer
for better steering response. We believe this is a game changer for the
industry, a great example of improved performance through innovation.”