- The Washington Times - Friday, December 14, 2001

Pickup trucks have a reputation for being much harder to handle than conventional passenger cars.

A four-wheel steering system GM introduced this fall may forever change the perception and expectations of pickup truck drivers however. Four-wheel steering gives pickups tremendous maneuverability improvement at both slow speeds for parking and at highway cruising speeds for vehicle stability, even when towing a trailer.

"It's the hallmark of what GMC has to offer," said Lorraine Babiar, assistant brand manager for Sierra pickups, in describing the new Quadrasteer four-wheel steering system that became available in November. After four months of exclusive use by GMC, Chevrolet will also offer Quadrasteer for Silverado pickups.

In a recent test of Quadrasteer, I found the 4WS system makes parking a big pickup in an ordinary mall parking lot space much easier than attempting the same feat with conventional front steering. Without four-wheel steering, I made several attempts before I could fit the pickup into the parking space. Switching on Quadrasteer, I was able to maneuver into the space on the first try.

Quadrasteer makes a pickup's curb-to-curb turning diameter about 20 percent smaller, almost equal to that of a Saturn coupe. With two-wheel steering, the turning radius is 47.5 feet vs. 37.5 feet with Quadrasteer. The Saturn coupe's turning radius is 37.1 feet.

Miss Babiar said that drivers who are now intimidated by conventional pickups won't be if their vehicle has Quadrasteer. And unlike four-wheel drive, which most people use only infrequently, if at all, Quadrasteer is a feature that drivers will use every day.

How does Quadrasteer work? For low-speed turning, the rear wheels steer opposite of the front wheels to "pivot" the vehicle tightly. In normal driving, the rear wheels do no steering. At higher speeds, the rear wheels steer in the same direction as the front wheels, thereby improving stability, particularly in towing trailers of up to 8,000 pounds. It takes a little adjustment to get used to Quadrasteer because you do not have to turn the wheel very far to make steering corrections.

Maneuvering trailers into camping spots or on boat ramps is likewise made easier by Quadrasteer. It also makes lane changing and passing less of a problem. For the more adventurous who want to travel on narrow mountain roads with hairpin turns, Quadrasteer provides more precise steering that keeps you following the track more easily.

The entire Quadrasteer system adds about 300 pounds of weight to the vehicle. This weight includes speed and steering-wheel position sensors, an electrically driven rear actuator unit, rear-axle knuckles that allow the wheels to pivot, and a controller that processes the sensor information and dictates phase and amount of rear-steer.

The heart of the system is a 128-kilobyte microprocessor in the control unit. The unit recalculates wheel angles and monitors all the diagnostics every four milliseconds. For failsafe operation, Quadrasteer actually has two microprocessors. Separate answers are compared to make sure codes are executed properly. If the system does not execute the codes properly, it shuts down. If Quadrasteer fails despite these engineering safeguards built into the system, you do not lose control of the vehicle. If anything happens to the system, the worst result is that you are restricted to two-wheel steering.

Quadrasteer is available exclusively in the GMC all-wheel-drive Sierra Denali, a half-ton short-box pickup, as standard equipment. It comes in at a pricey $44,000 with the four-wheel steering that's part of a $4,000 option package. In February 2002, Quadrasteer will be available on other GMC and Chevrolet full-size pickups.

Miss Babiar said that GM expects to sell 35,000 to 40,000 pickups with Quadrasteer in 2000; about 15,000 of those will be in the Sierra Denali. GM is considering equipping other trucks in its lineup with Quadrasteer, including the Chevrolet Suburban. Delphi Automotive Products developed Quadrasteer when it was still owned by GM, which has exclusive rights to the system for a few years, but Delphi says it will seek other vehicle makers as customers.


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