The 2011 Chevrolet Silverado Heavy Duty might not look all that different from the outgoing model on the outside — much like its parent company might not look significantly changed to a casual observer — but underneath, almost everything has changed.
The traditional Chevy power dome hood is back with the strongest styling we've seen since 2003. The chrome-framed grille has a larger bow tie, and the front bumper has been revised. Huge metal flares at the corners of the front bumper have been softened by reducing their height. Also, the inlet in the middle of the front bumper that feeds air to the truck's transmission oil cooler is about a third larger than the current inlet.
New for 2011 is a choice of 17-inch standard or brand-new 18- or 20-inch wheels for single-rear-wheel trucks. The dual-rear-wheel tires remain 17s, but they now can accommodate a taller aspect ratio tire — up to LT235/80R17 from today's LT225/75R17, something many GM HD buyers have been asking for.
Unfortunately, the bolt pattern on the new wheels is slightly different from the 2007-10 trucks, so you can't retrofit the new wheels onto the current pickups. The eight-lug count remains the same.
What's changed underneath? A better question is what hasn't. The front stabilizer bar link that connects the stabilizer bar to the lower control arm is carried over from the 2007-10 HD pickup. That's it.
Much of the frame improvements were aimed at giving the 1-ton 3500 Silverado maximum towing and hauling capability in the segment. GM has Ford's once-untouchable specs right in its crosshairs. Maximum trailering is up to 20,000 pounds pulling a fifth-wheel trailer with a DRW Duramax diesel and up to 14,500 pounds pulling a fifth wheel-trailer with a SRW 6.0-liter gas V-8. GM says the towing specs were calculated using the new J-2807 trailer towing standard that all truck manufacturers will eventually follow.
Maximum payload is up to 6,335 pounds with the DRW 6.0-liter gas V-8 and up to 5,724 pounds with the DRW 6.6-liter Duramax V-8.
The stronger frame is also said to help reduce noise, vibration and harshness, particularly up front. The engine mount brackets have been strengthened, and their positions supporting the engine are optimized so that the brackets' attachment points are now set relative to the center of the frame rail instead of offset at an angle, which had caused unwanted engine vibration.
There are a total of 11 different frame assemblies, depending on cab configuration, wheelbase, weight class and whether it's a pickup or a commercial chassis cab.
In the front suspension, the upper control arm is now made from forged instead of cast steel for increased strength and weight savings. The cast-iron lower control arm has been bolstered to handle greater loads. To help improve ride quality, two urethane jounce bumpers instead of one are mounted to the frame to cushion each side of the lower control arm, and there's also a new upper shock mount attachment design as well as all-new shocks.
Everything else up front is larger, too. The bolt capacities and diameters have increased from 16 mm to 18 mm. There's also a new steering box with a 16-1 turn ratio and larger front linkage to manage increased front-end loads resulting from the improved front gross axle weight rating, which has jumped from 4,800 pounds to 6,000 pounds.
The front differential is still 9.25 inches and keeps its aluminum housing, but the half-shafts, wheel bearings and lower ball joint have all been upsized. Internally, the ring-and-pinion gears have been strengthened.
Like the 2009 Chevrolet Silverado 1500 half-ton and 2010 Ram heavy-duty pickups, GM has replaced the old rubberlike cab mounts under the C-pillar with a new fluid-filled hydromount that helps reduce beaming and bounce over rough highways.
At the rear, the gross axle weight rating has increased from 8,200 pounds to 9,750 pounds to support the new 6,335-pound maximum payload rating, and the new asymmetric leaf spring packs with 3-inch-wide springs, up from 2.5 inches, to help reduce axle wrap and wheel up in low-traction or full-power-start situations. Compared side by side with the old frame, the rear spring hangers are now extremely well-integrated with the rails instead of looking like they were hung on with a few bolts and rivets.
Like the front differential, the size of the rear differential remains unchanged at 10.5 inches or 11.5 inches. The gears and bearings have been strengthened to handle increased power from the new Duramax V-8 diesel.
The final drive ratio won't be numerically smaller than the current truck's 3.73. A 4.10 rear axle will be optional.
Finally, a new integral trailer hitch will see its conventional towing capacity rise from 13,000 pounds to up to 16,000 pounds.
It's not just the stronger frame and running gear that support the increased towing and hauling numbers in the 2011 Chevrolet Silverado HD. There's also a revised 6.6-liter Duramax clean diesel that produces 397 horsepower and 765 pounds-feet of torque, beating the power figures for Ford's 6.7-liter Power Stroke diesel V-8. A new 36-gallon fuel tank extends the driving range of the 2011 Silverado HD. It's standard on long and short box versions. GM promises up to a 680-mile range, or about 18.8 mpg.
The new Duramax is also rated to burn up to B20 biodiesel (80 percent conventional ultralow-sulfur diesel and 20 percent biodiesel).
The six-speed Allison automatic transmission bolted to the back of the Duramax also helps improve fuel economy. It can lock up its torque converter (used to transmit engine power to the truck's transmission) faster and stay locked longer. Think of it as taking some of a manual transmission's inherent fuel economy advantages and applying them to an automatic gearbox. There's also reduced spin losses inside the transmission.
The 2011 Silverado adds the first application of trailer sway control to GM's full-size pickups. It works using the truck's antilock braking system and integrated trailer brake controller to brake individual wheels on the pickup automatically when it senses dangerous yaw in the rear of the truck from the trailer, which could happen if weight unexpectedly shifts inside the trailer. If the trailer has electric brakes and is connected to the Silverado's 7-pin trailer connector, the truck can also automatically apply the trailer's brakes to stop dangerous sway. TRW is the supplier for the system.
Another new safety feature can help with hill starts. Hill-hold assist will automatically apply the vehicle's brakes for 1.5 seconds once you lift your foot off the brake when you're on an incline. It's part of the Silverado's integrated trailer brake controller, so it will apply the trailer's brakes, too, if it has electric brakes.
Finally, all SRW Silverado HD pickups will come standard with GM's StabiliTrak stability and traction control system. Though it's not required on trucks with a gross vehicle weight rating of more than 10,000 pounds, on the GM pickups it will run up to the heaviest 11,600-pound GVWR.
As much change as there is under the Silverado's skin, interior changes are virtually nonexistent. There's available mobile Wi-Fi, USB and Bluetooth wireless connectivity and OnStar 9.0, which can stop the vehicle remotely if it's stolen.