VUE'S CHASSIS CONTRIBUTES TO NIMBLE HANDLING

VUE's state-of-the art chassis plays a critical role in making Saturn's new sport-utility drive, ride and handle as easily as a car. Key aspects of the chassis include electrically-assisted power steering that provides assist on demand, and four-wheel independent suspension that enables responsive handling and a controlled ride on a variety of road surfaces.

"The Saturn VUE was engineered to be fun to drive," said Jim Ulrich, Saturn vice president of engineering. "Because the vast majority of SUV owners never engage in rugged off-road driving, a more car-like performance is best suited to their lifestyles. While the VUE gets excellent traction, especially with all-wheel drive or traction control, our primary focus was on developing a smoother ride and more responsive handling."

Electric power steering
The Saturn VUE introduces the world's first application of an electric power steering system in an SUV. This system allows easy maneuvering and parking around town, while consuming less fuel than traditional hydraulic systems.

Fuel efficiency is improved because no engine power is needed to drive a hydraulic pump. While there is an electrical load through the generator, the load is negligible in the straight-ahead position in which most driving is done. In contrast, hydraulic power steering systems still consume some power in the straight-ahead driving mode.

In addition to fuel economy, the primary benefits are in packaging and performance. Eliminating the hydraulic pump on the engine and lines to the rack-and-pinion gear cleans up the underhood environment. On the performance front, the electric control unit can be programmed for desired performance characteristics. This unit monitors various sensors and controls the amount of assistance provided by an electric motor mounted adjacent to the steering column.

Sensors in communication with the electric power steering controller provide steering torque and vehicle speed information. Algorithms programmed into the controller command the electric motor to provide more assist at low speeds to assist parking maneuvers. As road speed rises, the assistance gradually tapers off. However, during a high-speed, rapid-steering maneuver such as emergency avoidance, the system's torque sensor automatically adjusts assistance so the driver doesn't perceive an undesirable steering effort.

Steering ratio is variable through the rack travel. A slow on-center ratio was selected to give the VUE optimal steering stability when the wheel is in the center position.

Strut-type front suspension
The Saturn chassis team chose a strut-type front suspension that provides long wheel travel, which benefits ride and handling. The VUE's strut system yields 128 mm of jounce travel and 87 mm of rebound.

The front suspension is carried by a perimeter-type cradle assembly, consisting of a large, U-shaped hydroformed tube welded integrally with a rear crossmember. The cradle is rigidly attached to the space frame at four widely-spaced mounting points. The stamped-steel, A-shaped control arms each have one pivot bushing in line with the center of the wheel, and another positioned further to the rear.

The forward bushing, which transmits most of the cornering force, is tuned for maneuverable handling and precise steering response. The larger, rear bushing is configured to allow controlled rearward movement of the front wheel, minimizing harshness transmitted to the space frame from pot-hole impacts.

A front stabilizer bar is mounted to the rear portion of the subframe. Connecting each end of the bar to the lower portion of the front strut by a direct-acting link maximizes its effectiveness. The rack-and-pinion steering gear is located at the rear of the subframe and is supported by two tuned rubber mounts.

Four-link rear suspension
The desire for exceptional ride and handling qualities led chassis engineers to choose an independent, four-link rear-suspension design. The suspension system uses a trailing arm plus three additional locating links to help provide safe, predictable handling.

The trailing arm, a vertical-blade-type design, is bolted directly to the wheel hub at its rear end and is attached to the space frame through a large-volume rubber bushing at the forward end. The bushing is tuned for a smooth ride, low road noise, minimal impact harshness and optimal wheel location.

The largest of the remaining three locating links runs between the rear subframe and the wheel hub, with a smaller one positioned ahead of the axle centerline. These two lower links help provide safe and predictable responses to steering inputs, including aggressive emergency maneuvers. In combination with a single upper lateral link, the two lower ones also determine each rear wheel camber pattern, the change of vertical orientation with respect to the road with up and down travel. Rear-wheel travel is 122 mm in jounce and 83 mm in rebound, which is longer than most competitive SUVs.

A stabilizer bar runs across the rear surface of the subframe and is connected to each lower, rear suspension member through short tie links.

Brake system
Power-assisted front disc and rear drum brakes are standard on the VUE, with a Bosch 5.3-series anti-lock braking system available as an option on all models. This system enhances safety by allowing the driver to maintain a level of steering and control in many different braking situations.

An electronic traction control system, available only on front-drive vehicles, helps prevent wheel spin in slippery conditions by retarding the ignition timing and reducing fuel delivery to reduce engine torque.

Wheels and tires
The VUE's wheels and tires were chosen with an emphasis on providing smooth and quiet performance in a variety of road situations, including wet, snowy and dry conditions. Sixteen-inch steel wheels are standard with VUEs equipped with the 4-cylinder engine, with aluminum alloy wheels offered as an option. Cast aluminum 16-inch wheels with a different face design are standard with V6-equipped models.

Bridgestone all-season touring radial tires in a P215/70SR-16 size are standard with front-wheel drive. All-wheel-drive vehicles are equipped with larger Bridgestone P235/65SR-16 size radials. Black sidewalls are common to both tire designs.

Fuel tank
For its 15.5-gallon fuel tank, VUE uses a molded multi-layer design that facilitates the best use of space in a safe location ahead of the rear suspension components and under the rear seat.

# # #