<%@LANGUAGE="VBSCRIPT"%> ROCKCRAWLER.com - GMC First to Offer Four Wheel Steering on a Full-Size Truck. Quadrasteer on 2002 GMC Sierra Denali


GMC QuadrasteerDetroit, Michigan - General Motors has taken the industry lead by offering the Quadrasteer four-wheel-steering system for the first time in a full-size truck. The innovative system, which makes driving a truck safer, easier and more convenient, will debut on the GMC Sierra Denali full-size pickup in the fourth quarter of 2002.

Quadrasteer marks a milestone in full-size truck handling and control.

It’s an electromechanical system that turns the Sierra Denali’s rear wheels (up to 12 degrees) in relation to the front wheels, resulting in unprecedented low-speed maneuverability and high-speed stability.

"Quadrasteer is truly a game-changer," said Gary White, vehicle line executive, GM full-size trucks. "Although four-wheel steering has been available in cars, this is the first application in trucks, where the benefits are even more apparent."

GMC Quadrasteer GMC Quadrasteer

Three driving modes

GMC QuadrasteerQuadrasteer offers a choice of three driving modes, and is engaged by controls conveniently located on the instrument panel:

"2WS" allows the truck to operate like any two-wheel-steer vehicle.

In "4WS" mode at lower speeds, the rear wheels turn in the opposite direction of the front wheels, which helps the vehicle make tighter turns, such as when cornering or slipping into a tight parking space. Quadrasteer reduces the Sierra Denalis’s turning diameter by 21 percent, from 46.2 ft. to 37.4 ft., which is comparable to that of a Saturn S-Series coupe (37.1 ft.).

At higher speeds, the rear wheels turn in the same direction as the front wheels, reducing the vehicle’s "yaw," or rotational motion, for dramatically better stability during lane changes and when being passed by a large truck.

Quadrasteer also benefits customers who trailer, enabling the Sierra Denali to change lanes with more confidence and with hardly any trailer sway. During low-speed towing maneuvers, such as backing into a boat launch or parking a camper, four-wheel steering greatly improves the trailer response to steering input.

The "4WS Tow" mode reduces the amount of rear-wheel steer at lower speeds and increases rear wheel steer at higher speeds to provide even more stability than regular four-wheel steering.

Turning Radius Comparo

Maneuverability and stability

"Once you drive the Quadrasteer Sierra Denali, you’re a believer," said White. "Combining the truck’s 325 horsepower Vortec 6000 V8 and all-wheel drive with the maneuverability and stability of Quadrasteer delivers simply astounding performance. Four-wheel steering is one of many innovative technologies and features within GM’s full-size truck portfolio which will provide customers with real benefits while reinforcing brand equity."

Quadrasteer operates by sensing the driver’s desired steering input by way of a steering wheel position sensor. This information is fed to a microprocessor that determines the appropriate rear-wheel angles, based on steering input and vehicle speed. The microprocessor feeds its data to an electric motor which, based on algorithms, drives the rear steering rack through a planetary gearset.

If a system failure is detected, Quadrasteer’s failsafe mechanisms revert to normal two-wheel steering.

GMC Quadrasteer GMC Quadrasteer

Increased capabilities

With Quadrasteer, the Sierra Denali gets a new standard 4.10 rear axle ratio which increases its Gross Combined Weight Rating by 2000 lbs. to 16,000 lbs. and boosts its maximum trailer rating from 8,700 lbs. to 10,000 lbs. A larger 9.75-inch rear ring gear is used to increase the rear axle’s gross weight rating by 250 pounds to 4000 lbs. The larger rear axle increases the GVW rating 400 lbs. to 7200 lbs.

To allow more turning clearance for the rear tires, the Quadrasteer-equipped Sierra Denali has flared composite rear fenders that give the vehicle a brawny, capable look. Their reinforced reaction injection molded construction also resists dents and corrosion.

The Sierra Denali also adds new safety features, including standard roof marker lamps and fender-mounted clearance lamps. Interior box dimensions remain the same.

Quadrasteer will also be offered as a regular production option on other properly equipped GMC Sierra wideside and Chevy Silverado fleetside pickups beginning in the first quarter of 2002.

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