For the 2001 model year, GM will offer a new heavy-duty, or HD, pickup truck to the consumer. These new trucks will bring medium-duty technology to the light-duty truck user. This means more than the new distinct appearance, brought about mainly through the use of all-new sheetmetal from the doors forward. These trucks sport stronger frames and tougher drivetrains. The 2001 GMC Sierra and Chevrolet Silverado heavy-duty trucks are the results of GM's concerted efforts to build a market-leading heavy hauler, and these trucks have more than hit the mark. GM spared no effort on the design of the new trucks' chassis, suspension, and powertrain. The drivetrains have been vastly improved for the HD truck line. Here's a rundown of what's new in that department.
First off, the venerable Vortec 6000, 6.0L, small-block has been improved and produces 325 hp at 5,000 rpm and 360 lb-ft of torque at 4,000 rpm. This means 70 hp and 40 lb-ft more than the 5.7L (350-cid) engine it replaces. But GM didn't stop there. The new HD trucks will be offered with new-generation big-block and diesel engines too.
The big-block is the Vortec 8100 - an 8.1L or a 494-cid motor, the most technologically advanced big-block ever offered by GM. This motor has a 4-1/4-inch bore and a 4-3/8-inch stroke. This powerful new Rat motor produces 340 hp at 4,200 rpm and 455 lb-ft of torque at 3,200 rpm. The Vortec 8.1L engine incorporates advancements such as Teflon-coated pistons to reduce friction and stainless steel exhaust manifolds. For durability, the new engine has forged steel rods, a four-bolt main block, a nodular iron crankshaft, and hydraulic roller valve lifters that roll atop a steel camshaft. The aluminum intake manifold boasts equal-length runners; a sequential multiport fuel injection system delivers the fuel; and the ignition system is a coil-near-plug setup.
For those who like diesel motors, GM will offer the all-new Duramax 6600 (6.6L or 402-cid) mill. This new engine is compact for a diesel but offers more torque and horsepower than the competition's current diesel line. This beast of an engine produces 300 hp at 3,100 rpm and an astounding 520 lb-ft of torque at a leisurely 1,800 rpm. The Duramax is an all-new design with features that include: high-swirl aluminum cylinder heads with four valves per cylinder; a state-of-the-art Bosch fuel-injection system; a nitrided forged-steel crankshaft; and a single turbo mounted in the engine's V. The oil-burner also boasts a gear-driven camshaft that opens hydraulic roller lifters, an integral oil cooler, a gear-driven water pump, and pistons that are cooled with oil sprayed from small jets located on the lower segment of the cylinder walls. It's a true performance engine that just happens to be a diesel.
To handle the power of these two new engines, three new transmissions will be offered. For the small-block engine, the automatic will be an improved version of the L480E that is used in today's trucks. The manual will be the tried-and-true NV4500. Duramax and big-block owners will be driving with a ZF S6-650 six-speed manual with a potential load rating of 26,000 pounds or a new Allison 1,000-series five-speed automatic. The Allison five-speed auto is an industry first for light-duty trucks. This commercial-level transmission will surely be able to handle everything the average Joe or Jill can throw at it. Even the parking paw is rated to a true 26,000 pounds GCW. The Allison's high-tech features also include fuzzy logic-controlled Engine Grade Braking. This is essentially a series of micro-processors that sense the truck's load, its deceleration rate, and its overall speed whenever a downhill grade is encountered. Then, based on instant calculations, it automatically downshifts the Allison tranny from Fifth to Fourth and to Third if required, thus keeping the brakes from becoming dangerously overheated. The Allison's hard parts include a torque converter with fully brazed vanes and clutches that automatically and continually adjust to compensate for wear. In addition, the transmission has an external filter for easy maintenance. Performance is terrific with the Allison; its five forward speeds help the HDGM trucks launch from a standstill, and improve the new trucks' grade-climbing cap-abilities, towing capacity, and overall fuel efficiency. The Allison 1000 series is an advanced medium-duty truck transmission for the next millennium and will greatly enhance the new engine offerings.
GM recognized that owners of work trucks appreciate a high degree of comfort while they're at the controls, so the Silverado and Sierra HD models can be outfitted in a manner akin to a luxury car. Available as options are leather-covered, electrically adjustable, heated seats (comfy); power-operated windows, door locks and mirrors; a full gauge package; an overhead console; deep-pile, color-keyed carpeting with carpeted floor mats; and a powerful AM/FM/CD sound system.
GM is now offering the G80 option on its trucks for the 8.6-inch and 11-1/2-inch axles. The Eaton locking differentials provide that added traction edge when needed but act as open differentials during normal driving. The 8.6 is the highest-volume differential with more than 800,000 sold in 1999. The 8.6-inch locking differential is offered as optional equipment on all GM and Chevrolet 1/2-ton pickups and sport utilities. It is standard equipment on the Yukon Denali, the Cadillac Escalade, and the Tahoe and Yukon Z71 packages.
The 11-1/2-inch locking differential will be used on GM and Chevrolet 2500HD and 3500HD trucks. It is offered as an option on all dual-wheel applications and is standard equipment on dual-wheel vehicles. The 11-1/2-inch locking differential is a new product that was specifically designed for the new 1-ton axle. In addition, Eaton also produces 7.6-inch, 8-inch and 9-1/2-inch locking differentials. These products are available on S-10, Sonoma, Astro, Safari, and all 3/4-ton pickups and sport utilities.
Eaton locking differentials have been upgraded over the past several years and offer superior performance and quality. Upgrades include stronger housings; forged gears; carbon-bonded discs that are used in the clutch packs and upgraded cam plate; and lockout and engagement mechanisms to provide improved strength and durability. The Eaton units provide a considerable traction, advantage compared to limited-slip products used by other OEMs.
Quadrasteer From GM
Slated for introduction on select 2002 light-duty trucks and SUVs will be GM's QUADRASTEER. GM has the inside track on the Delphi system, with Delphi having made a commitment to supply GM with QUADRASTEER technology before any other manufacturer - namely Ford or DaimlerChrysler - is allowed to equip its trucks with the innovative setup.
For now, here's what we know about GM's QUADRASTEER along with a teaser photo of Ford's version of the Delphi system.
GM's QUADRASTEER is a fly-by-wire/electronically controlled rear-wheel steering system that has four main components: an electronic front wheel position sensor; a steerable solid rear axle; an electric motor-driven actuator, and a master control unit.
In operation, QUADRASTEER operates in three principal phases: negative, neutral, and positive. At low speeds, QUADRASTEER steers the rear wheels in the opposite direction of the front wheels, which is the negative mode. At moderate speeds, QUADRASTEER keeps the rear wheels straight; this is the neutral position. At higher speeds, the rear wheels are set in a positive phase, meaning that the front and rear wheels steer the same direction. When QUADRASTEER is in its negative phase, tight turns and low-speed maneuverability is greatly enhanced. When in its positive phase, QUADRASTEER provides a stabilizing effect, because it reduces a vehicle's lateral rotational motion, also known as yaw or sway. There's little denying QUADRASTEER's effect on a truck's turning radius. Just think how well a QUADRASTEER-equipped 4x4 would handle the tight stuff on tricky, technical trail; just think what a short-wheelbase 4x4, such as a Jeep, could do with QUADRASTEER; just think...