If General
Motors has one of the slickest
surfaces on Earth for testing vehicles,
than Ford Motor Company must have one of the roughest.
At Ford's
Arizona Proving Ground (APG), its F-Series pickups are driven
over 50 miles of torturous terrain specifically developed to shake,
twist, rattle and batter the trucks.
One of the
test tracks is called 'Silver Creek'. It was described in a Ford press
release late last year as the following:
"Silver
Creek combines two extremely rough roads. One section of the route
has 15 distinct types of chuck holes while the other is made from broken
pieces of concrete."
According
to Charlie Tegarden, Ford
durability engineering supervisor, "Silver
Creek is foot-for-foot the roughest man-made durability test road in
the world."
The movies
are dramatic. The first (above) shows each truck serially. The second
(below) shows them in parallel. Each truck enters Silver Creek at 28
miles per hour - near the upper boundary for maintaining control. Pay
close attention to the driver's hands on the steering wheel when the
camera pans to the cab as the rapid fire torsional forces expose any
weakness in suspensions, frames, and body components.
The F-150,
now three model years old, seems to do best overall. It's followed
closely by the Silverado.
Both the
F-150 and Silverado have fully
boxed frames that are more resistant to twist than the Toyota's
partially-boxed C-channel chassis. The F-150's advantage
versus Silverado appears to come from rear shocks that are mounted
outboard from the frame rails - a setup that provides better
leverage against axle movement than the Silverado's inboard mounted
shocks. The result is much more jounce seen in the Chevy's rear axle. Front
suspension performance appears to be in favor of the Silverado's new
independent coil spring setup but the Chevy suffers cosmetically as
its fuel filler door opens and shuts from all the bouncing.
Bed movements
in the F-150 and Silverado are relatively limited though, compared
to what's seen in the Tundra. The rear of the Tundra's cargo box flexes
and twists violently as the front gouges the back of the cab. There
are portions of Silver Creek where the frequency of severe bumps causes
an especially large degree of torsional resonance to show in the bed's
sides.
So how does
the unrealistic surface of Silver Creek relate to what these trucks
might encounter in the real world? At some point in time almost
every pickup is going to be overloaded or stressed past its
operating limits, even if it's only for a few seconds. Its engineering
for these types of events that make for really tough trucks.
