Automotive Engineering - October 2018 - 22

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With 2019 Sierra, GMC puts brand differentiation behind it-literally

That the all-new 2019 GMC Sierra 1500 pickup uses GM's
same T1 fullsize-truck architecture as the 2019 Chevrolet
Silverado was of course preordained. The new platform
comes with a raft of design and engineering tricks that mostly
targeted weight reduction and increased structural integrity
and refinement via sophisticated mixed-metals applications
(https://www.sae.org/news/2018/04/truck-tech-war).
Mostly employing the same mechanicals as the Chevrolet
Silverado, the job for the GMC brand typically is delivering an
appropriate degree of differentiation from its high-volume Chevy
counterpart. That's been executed with any number of strategies
over the long pickup-truck history of both marques, but the 2019
Sierra does so with maybe the most interesting ammunition yet-
and almost all of it located at the back: a carbon-fiber reinforced
plastic (CFRP) cargo box and a clever reconfigurable tailgate.

Weight-chopped box

The CFRP cargo box accounts for 62 lb (28 kg) of the Sierra's
curb weight reduction that totals as much as 360 lb (163 kg), including 88 lb (40 kg) chopped from the T1's fully-boxed frame.
The company also claims best-in-class resistance to just about
every destructive thing that can happen to a pickup box, thanks
to the CRFP material supplied by Japan's Teijin; the company's
Continental Structural Plastics plant that makes the CRFP "inner"
is located near the Sierra's assembly plant in Fort Wayne, Indiana.
Teijin recently broke ground for a carbon-fiber production
plant in Greenwood, South Carolina, as the cornerstone of a
push to cut the cost of the material and drive wider use in the
auto and aerospace sectors.
"A lot of the intellectual property comes from the way we
manufacture it," Tim Herrick, executive chief engineer for GM's
fullsize pickups, told Automotive Engineering at the media
launch for the Sierra Denali and AT4, the first models to hit
showrooms; buying the top-of-the-line Denali, by the by, will
be the only way to get the carbon-fiber box, for now exclusive
to GMC. Constructed on for the short-bed configuration of
Denali, the 5-ft 9-in short box is 1 in (25 mm) longer and 2 in
(50 mm) taller than that of the previous generation Sierra.
22 October 2018

Detail of the construction of the 2019 Sierra's available carbon-fiber cargo
box, for now available only for the top-trim Sierra Denali.
Another advantage, said Herrick, is that the carbon-fiber
material box also boasts 1 cu ft more cargo space because its
sidewalls are thinner. This in addition to the 7 in (178 mm)
wider all boxes already are for the Sierra line.
Herrick would not say how much GM plans to charge for
the optional box, but he and other engineers seem to expect
the availability will expand to other models, suggesting the
price will not be outlandish.
The rollout scheme does recall, however, a previous GM attempt in the early 2000s to market a fully composite bed-
dubbed Pro-Tec-for fullsize Chevy and GMC pickups. Sales
were dismal because, among other factors, Pro-Tec's price
was a multiple of the cost to install an optional plastic bedliner that delivered most of the same advantages and typically netted more profit for dealers.
For the new CarbonPro Box, Herrick said the carbon material goes into the tool "almost like an origami, all folded up,"
and then is heated to form the net shape. Apart from the material itself, the CarbonPro Box installs on the assembly line
essentially in the same fashion as the standard box, he added.

Gate-a-palooza

The Sierra's back-loaded story doesn't end with the CarbonPro
cargo box. Access to it and the standard steel boxes on the
Sierra Denali, AT4 and SLT trims comes via the new MultiPro
tailgate, a split-gate design that provides six different configurations intended to facilitate access to the bed, provide a fullwidth step into the bed and serve essentially as a built-in bed
extender or "load stop" to secure long, flat items.
Our favorite configuration, however, proved to be the one
that allows the upper portion of the gate to be partially folded
to create a comfortable standing-height work surface. The
MultiPro gate, another feature for now exclusive to GMC, is
too useful to not proliferate and it's widely expected the
multi-configuration gate soon will extend to other models.

Engine extravaganza

The passenger-vehicle world may be converging on 2 liters,
but don't expect the pickup market to follow. The 2019 Sierra
AUTOMOTIVE ENGINEERING

BOTH IMAGES: GMC

The AT4, is a new,
off-road-oriented
model for the wideranging 2019 Sierra lineup.
https://www.sae.org/news/2018/04/truck-tech-war
Automotive Engineering - October 2018

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