Chevy's heavies in 2011
Chevrolet emerged from two years of corporate restructuring, swinging hard at the heavy-duty market (the only bright spot in otherwise dismal recent vehicle sales for the company). Chevy introduced new models – new models with a great many advances.
The heavy-duty line has 11 2500 HD and eight single- and dual-rear-wheel 3500 HD models (including a new Crew cab). The line runs with a new Duramax 6.6-liter diesel and an Allison 1000 auto transmission. The Duramax (over 1.3 million built since 2000) was upgraded with a wide variety of refinements. The Allison has higher torque capability and such features as a driver shift control with tap-up and tap-down shifting.
This engine-tranny combination also offers benefits such as the exhaust brake system, new front and rear suspension, hill-start assist, and trailer sway control. The smart exhaust brake system automatically slows both the truck and trailer on descents. The hill-start system engages when sensors detect the vehicle is on a 5% grade or greater. It holds the brakes for 1.5 seconds or until the gas pedal is pressed to prevent rollback.
The gas platform on the Silverado HDs includes the Vortec 6-liter V-8 engine combined with Hydra-Matic 6L60 six-speed automatic.
Chevy engineers also took to the trucks’ frames by adding more cross sections and employing higher-strength steel. Bending and beaming stiffness of the frames are increased 92% and 20%, respectively, with fully boxed sections and enhanced torsional stiffness. Improvements in the framing include larger engine and tranny mounts coupled with a 125% stiffer front frame structure. A completely redesigned independent front suspension system offers up to a 25% greater front axle weight rating of up to 6,000 pounds.
New larger asymmetrical leaf springs improve ride. The 2500 HD has a two-stage leaf; the 3500 HD has a three-stage design. Other improvements include a new frame-mounted fifth-wheel mounting that makes installation easier.