The GMC Sierra HD All Terrain concept is GM’s answer to the go-anywhere at any speed mightiness that is the Ford Raptor.
The best aspect of the All Terrain may be its Duramax diesel. It’s a tough-as-nails engine that produces 397 horsepower (296 kW) and 765 lb.-ft. of torque (1,037 Nm). The Sierra All Terrain HD also features four-wheel drive, with automatic locking front and rear differentials, while the 14-inch, four-wheel disc brake system from the production Sierra HD provides the stopping power for this unique off-roader.
The new 2011 Sierra HD underpins the All Terrain HD concept, with a modified, production-based 4WD chassis and the Duramax diesel/Allison 1000 six-speed powertrain. The enhanced suspension and unique body dimensions, including increased ground clearance and wider track, as well as greater approach/departure angles, deliver off-road capability while maintaining HD levels of payload and trailering capacity.
Based on the chassis of the 2011 Sierra HD trucks, the All Terrain HD features a fully boxed steel frame with exceptional strength and torsional stiffness. It incorporates the production models’ new independent front suspension and asymmetrical rear leaf-spring suspensions, but with a wider 73-inch (1,853 mm) track (front and rear) that enhances stability during off-road and highway driving. A production Sierra 2500HD has front and rear tracks of 68.8 inches (1,748 mm) and 67.3 inches (1,709 mm), respectively.
An increased ride height provides greater ground clearance of 21.1 inches (536 mm) at the rockers and 11.8 inches (300 mm) at the skid plates, while specialized Fox off-road shocks deliver exceptional damping on tough terrain. They were created specially for the All Terrain HD, with specific valving. The shocks feature visible, remote fluid reservoirs – connected to the shock bodies via custom hoses – mounted in the wheel house liners and are matched with front and rear jounce shocks. They add additional compression damping and more controlled rebound, which helps increase control, stability and handling.