The Sierra 2500HD is the heavy duty version of GMC's Sierra 1500 full-size pickup truck. It is positioned under the even more capable Sierra 3500HD and is also available in luxed-up Denali form. For the latest model GMC spent considerable time and effort reworking the powertrains and chassis underpinning the truck, but stopped short of a major reworking of the truck's sheet metal.
The Sierra 2500HD comes standard with a gas-powered V8, while a turbodiesel eight-cylinder is optional. The gas-burning 6.0 V8 puts out 360 horsepower and 380 lb-ft of torque, while the mighty diesel displaces 6.6 liters and makes a staggering 397 horsepower and 765 lb-ft at a usefully low 1,600 rpm. Both engines put their power to the ground via 6-speed automatic transmissions, though the diesel uses a heavy-duty Allison unit. Maximum payload and towing capacity are 2631 and 16,800 pounds, respectively.
Several features work together to make carrying and towing such heavy loads easier. A trailer-sway control system senses conditions of trailer sway and automatically intervenes with braking and/or reduced engine power to bring the trailer under control and keep its on its intended path. A hill start assist system engages when sensors detect the vehicle is on a grade of about 5 percent or greater, holding the brakes for 1.5 seconds or until the gas pedal is pressed in order to prevent rollback.
Finally, an exhaust brake, standard with the turbodiesel, uses the turbine control of the variable geometry turbocharger in addition to the compression of the engine to generate backpressure, slowing the vehicle without the driver applying the brakes. This helps to prolong brake life and prevent overheating on long, downhill grades.
GMC has upgraded the the Sierra 2500HD's brakes to a four-channel ABS system on single rear-wheel models and a three-channel system on dualies. The front and rear rotors are increased to 14 inches in diameter and the booster has been recalibrated.
Wheelbases are increased across the line to go with a the 11 new fully-boxed frames. GMC says rigidity us up 92 percent in bending and 20 percent in beaming, while the front structure is 125 percent stiffer than before. The frame-mounted hitch is now stronger thanks to a box tube design; it now supports 16,000 lbs.
The new frames hold an all-new independent front suspension that has a 25 percent greater front axle rating (6,000 lbs.). The basic design is unchanged, but stronger forged steel upper control arms and cast iron lower control arms add strength and reduce weight. GMC says that the system improves handling and ride while increasing strength for front end attachments.
The rear leaf spring suspension gains a larger asymmetrical leaf design that are wider than existing models. The 2500HD models get a two-stage leaf spring design, while 3500HDs get a three-stage setup. Gross rear axle ratings are up across the board.
The Sierra 2500HD also offers 170-degree rear access doors for extended cab models, bolstering interior cargo hauling ability.
Safety features include dual front and side airbags, while seat mounted pelvic/thorax and head curtain side-impact airbags are available as options.
Key Competitors
Full-size, heavy duty pickup rivals to the Sierra 2500HD include the Ford F-250 Super Duty and the Ram 2500.