2010 Chicago Auto Show: 2011 Chevrolet Silverado Heavy Duty First Look, Part 1
Our first look at the 2011 Chevrolet Silverado Heavy Duty pickup is so large that we've split it up into two parts to make it easier to find the information and material you want to read first.
Part 1: Introduction, Frame, Suspension and Axle ChangesPart 2: Duramax Diesel, Allison Transmission, Safety Improvements and New Models
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It's been only three years since General Motors updated its heavy duty pickups, but in that time the company has been permanently changed by bankruptcy, organizational turmoil and dramatic changes in the consumer and political landscapes. Is the new 2011 Chevrolet Silverado HD strong enough to improve GM's fortunes? Will it beat new and improved competition from rivals Ram and Ford?
Who could have predicted in early 2007 — when the 2007 model year HD pickups went on sale — that GM's strength in big trucks masked giant weaknesses in its balance sheet and vehicle lineup that would financially unravel the company in 2009? GM wasn't ready for a spike in fuel prices and the end of the housing boom that became one-two punches that led to plummeting auto sales and the company declaring bankruptcy.
Last year the U.S. and Canadian governments finally stepped in to rescue GM by providing billions of dollars in loans while taxpayers in both countries grudgingly became owners of more than 70 percent of the company.
Today, GM has a fresh start to remake itself into a smaller, nimbler and greener company. The emphasis since bankruptcy — and since the Obama administration introduced tough, new fuel economy standards that take effect between now and 2016 — has been on smaller passenger cars like the Chevrolet Cruze, crossovers like the Chevrolet Equinox and alternative-fuel vehicles like the Chevrolet Volt. Not even the all-new Chevrolet Camaro muscle car has escaped downsizing. Over the long term, GM expects to sell more Camaros equipped with direct-injection V-6 engines than traditional V-8s.
"Some have asked the question, ’Are we still serious about trucks?’" said Rick Scheidt, executive director of product marketing, Chevrolet full and mid-size trucks. "The answer is a resounding yes."
And now the latest GM full-size truck is almost here. The 2011 Chevrolet Silverado HD 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.
Exterior
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, as we noted in earlier spy shots, the front bumper has been revised. Huge metal flares at the corners of the front bumper (unpopular with 2007-10 Chevy HD owners) 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.
Jim Mikulec, GM's lead development engineer for full-size trucks, has worked on the last four generations of GM's big pickups. He said almost all of the front-end styling changes are related to the truck's greatly improved towing and hauling capabilities.
"The larger inlet in the front bumper is primarily for better cooling," Mikulec said. "We knew where we needed to improve the airflow. We've got larger heat exchangers up front in the new truck. We've got a new hood because the radiator comes up higher. From my perspective, I wanted a huge grille with lots of cross-sectional area for airflow, but the styling folks came in and that’s why we went with the larger opening on the bumper."
Also new for 2011 is a welcome choice of 17-inch standard or brand-new 18-inch 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.
"The first [dually] that came into the garage with the new tires, the techs took a look and said it’s about time you put a larger tire on the trucks," Mikulec said.
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.
Frame Changes and Towing and Hauling Improvements
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.
To show off the Silverado’s new ladder frame, suspension and axles, GM helpfully provided a rolling chassis alongside the old and new frames to show the differences side by side.
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 SAE's new industry J-2807 trailer towing standard that will eventually be followed by all truck manufacturers.
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 frame rails are now fully boxed from front to back like a half-ton, instead of open C-channel, for improved rigidity and torsional stiffness. Most cross members now have rectangular profiles instead of rounded ones. The cross members are also welded instead of riveted to the frame rails, a welcome change that should improve durability.
Jeff Luke, GM's chief engineer for full-size pickups, said the new frame has five times the torsional strength, 92 percent better bending stiffness and 20 percent better beaming stiffness. The front frame bay cradling the engine is 125 percent stiffer than the old frame.
Torsional strength is how much the frame will twist side to side under load. Bending stiffness is how much the frame will bend under load. Beaming stiffness is how much the frame will flex as it's loaded in the center and supported at both ends. 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 bracket 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.
Suspension and Axle Changes
The rolling chassis in this picture (and the following photos) shows off both the old (dull) and new (shiny) frames grafted together.
While some 2011 Silverado HD buyers may be disappointed that GM has kept its trademark torsion bar independent front suspension instead of switching to a solid front axle — which offers better articulation and ground clearance for off-road applications — it's visibly beefier than before because of its larger diameter. It has a canceled Ford F-450 1.5-ton fighter to thank for that strength.
"Originally, when we scoped the program, we were going to make a heavier truck," Mikulec said. "A lot of components were sized for that truck that we have on the 1-ton. However, we never looked at a different front [suspension] setup. We want a common setup for both two- and four-wheel drive."
"Some may ask, ‘Why don't we have a F-450?’" Luke said. "We think we've increased the capabilities of the 3500 to the low end of the 450. And only about 9,000 F-450s were sold last year, so we think we're making the right decision."
In the front suspension, the upper control arm is now made from forged instead of cast steel, for increased strength and weight savings, while 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.
Regardless of cab, engine or driveline configuration, all Silverado HD pickups can accommodate the biggest snow plows built for HD pickups. In the old truck, the weight of the Duramax diesel and four-wheel-drive system limited the largest snow plows to regular-cab two-wheel-drive models. Only gas trucks could support the big plows. The torsion bar setup is also simpler than its predecessor. There's only one torsion bar cross member now instead of three, for easier packaging. Depending on the front GAWR, there are five different torsion bar rates . Previously, a single torsion bar was used for all models.
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.
"We kicked around doing something shorter," Mikulec said. "But it's not in the program for now. Our issue is the 11.5-inch axle. We'd have to tool up for something new like a 3.42 axle [which could help improve fuel economy in a trade-off for towing capability]. We're going to continue to kick around the idea because a 3.42 would sure get great mileage."
Finally, a new integral trailer hitch will see its conventional towing capacity rise from 13,000 pounds to up to 16,000 pounds.
"Overall, the truck is about 300 to 400 pounds heavier than what it replaces," Mikulec said. "That's the price of increasing the capacity of the truck. But if you look at our sales today, we don't sell a lot of 1-tons because we don't have the same capacity as other trucks. The numbers prove that out. The critical bit for the program was to substantially increase payload and towing, and that's what we've done.”
The old frame is on the left. The new frame is in the right. You can easily see the new larger cross members and the switch from an open C-channel to a fully-boxed frame at the top of the picture.
6.0-liter Gasoline V-8 Improvements
The 6.0-liter gas V-8 returns for 2011 with improvements that include a stronger 6L90 six-speed automatic transmission hanging off the back and a new camshaft. GM, however, is still silent on what those changes mean for performance.
Last year's power figures for the 6.0-liter were 353 horsepower and 373 pounds-feet of torque.
Part 2: Duramax Diesel, Allison Transmission, Safety Improvements and New Models
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