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The 2000 Cadillac DeVille

The year 2000 Cadillac DeVille
The 1999 Tokyo show
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CHASSIS UPGRADES IMPROVE DeVille'S COMFORT, SAFETY, STABILITY & ROAD POISE
DeVille moves to a new architecture for the 2000 model year, incorporating a host of functional and performance improvements. Key attributes of the new architecture are a significantly stiffer body structure, superior suspension geometry, larger brakes, a longer wheelbase and broader wheel tracks.

The DeVille takes up as much space as Wales, but isn't quite as pretty.

Driver control is improved by two enhanced features of the Northstar System. The first is StabiliTrak 2.0, the next evolution of Cadillac�s world-class stability control system, which is standard on the DTS and optional on the DeVille and DHS. In addition, the DTS comes standard with continuously variable road-sensing suspension (CVRSS) 2.0 with transient roll control, lateral support and enhanced stability. Combined with the G-platform architecture, these Northstar System upgrades deliver major improvements in stability, safety, road poise and ride.

Several fundamental design features are carried over in the new chassis design. The engine and transaxle assemblies are still transversely mounted on a rubber-isolated cradle to power the front wheels. The front cradle also provides a lower attachment for the MacPherson strut front suspension and a stable mounting location for the rack-and-pinion steering gear. As before, front and rear suspension systems are independent with coil spring elements. Electronically controlled air shocks at the rear maintain a level attitude with changes in passenger or cargo load. The slightly larger foundation brakes are vented discs in front and solid discs in back.

CLASS II NETWORK
DeVille�s Class II computer network forms the basis for the Northstar System�s integrated chassis controls. The new electrical system architecture, which debuted in the 1998 Seville, is one of the key benefits of DeVille�s move to a new platform. The new zoned electrical system combines extra features and added function while increasing reliability and significantly reducing the number, weight and complexity of electrical wires.

Instead of providing a separate wire for each and every electrical function, messages are digitally coded by an electronic module and then delivered along with thousands of other coded messages via just one wire. This technique, known as multiplexing, permits sharing of the information by various systems and modules. All systems of the vehicle share information along this network, allowing the sharing of key data.

The Class II label used to describe this architecture refers to the operating speed of 10,400 bytes of information every second. Since each message is composed of only a few bytes, the system is capable of delivering hundreds of messages per second. DeVille�s five major chassis systems - engine, transaxle, steering, braking and shock absorbers - are interconnected so that one helps the other deliver smooth, safe, surefooted performance.

CHASSIS FEATURES
DeVille�s new architecture is a fifth-generation refinement of General Motors� G platform. Special chassis features are:

Magnasteer variable-effort power steering. A magnetic field is generated in the steering gear�s control valve to permit varied steering effort requirements. Low efforts are selected for ease of parking. Higher efforts are specified at higher speeds and when the driver needs a more confident sense of the road. Steering effort also is increased during traction control actuation and during ABS braking events. Using an electrically generated magnetic field instead of the previous permanent magnet design eliminates the chance of audible electrical interference through the entertainment system. The use of cast-aluminum suspension control arms and knuckles, front and rear, minimizes mass.

Micro-alloy steel is used to save approximately one pound of mass per coil spring. A "dual-cannon" mounting system for the rack-and-pinion steering gear uses a rigid mount at the driver�s side of the car and a rubber-isolated connection at the opposite side. Attachment fasteners are reduced from five to two. This design significantly reduces car-to-car build variations, thereby improving steering characteristics.

FRONT CHASSIS
The front suspension lower control arm design has been optimized to provide low impact harshness, excellent road isolation and crisp steering response. This is achieved primarily through special pivot-bushing design features. The front rubber-hydraulic bushing has a very low longitudinal rate to allow each front wheel to move slightly rearward over a bump in order to reduce harshness. The rear pivot bushing is aligned with the wheel centerline and is tuned with a firm lateral rate to enhance steering response. Front chassis wheel travel has been increased from 186mm in 1999 to 197mm in the 2000 DeVille, enabling the suspension to better absorb energy if the car hits a pothole.

An improved engine mounting system minimizes noise and vibration transmitted to the passenger compartment. Two hydraulic mounts between DeVille�s front longitudinal body rails and at each end of the engine-transaxle assembly carry practically all of the powertrain�s mass. These mounts are positioned on the torque axis and are tuned for maximum isolation. The hydraulic feature permits a softer rate without allowing large movements at certain frequencies. Fore-and-aft mounts are tuned to handle the powertrain�s torque reactions. The two fore-and-aft mounts anchor to the cradle. The forward torque-reaction mount is a rubber-hydraulic design while the rear one is conventional rubber and steel composition.

REAR CHASSIS
The independent rear suspension features a cast-aluminum semi-trailing arm to locate each rear wheel and one lateral toe link per side to provide the desired wheel alignment during aggressive cornering maneuvers. Total wheel travel has increased from 190mm in 1999 to 255mm in the 2000 DeVille. The new suspension geometry also reduces rear impact harshness and pitch forward (dive) during hard braking. Air shocks are used in the rear to keep the car level by adjusting for passenger or cargo load.

A welded-steel T-shaped member supports the semi-trailing arms and the rear anti-roll bar. It�s attached to the body through tuned rubber mounts, providing a second level of road isolation. This member also protects the fuel tank. A new composite fuel tank is made of six layers of material to minimize vapor losses.

RIDE AND HANDLING
DeVille�s new chassis architecture offers the flexibility to provide various suspension system variations to suit different customer tastes. DeVille and DHS editions are equipped with luxury suspension tuning that emphasizes ride quality while providing excellent handling characteristics.

DTS is equipped with a more active suspension tuned for improved performance. The CVRSS 2.0 system comes with three significant enhancements - transient roll control, lateral support and stability control interaction.

CVRSS uses wheel-position sensors to read road conditions and fast-acting dampers at each corner of the car to continuously and instantly adjust ride and handling for any situation. At 65 mph, a damper can shift from full soft to full firm every 6 to 7 inches of road surface traveled. CVRSS manages both body and wheel motion. Damping is adjusted as necessary to control heave (up and down motion over road swells), pitch (front of car lifting while rear of car dives, or vice versa), roll in corners, and front-end lift during acceleration. On very smooth roads, damping forces are minimized to enhance isolation. To maintain ride comfort and stability at high speeds, damping forces are increased with vehicle speed.

The extensive use of electronic chassis controls to manage steering, braking, suspension damping and traction functions interactively means that more ideal settings can be provided for every driving circumstance. It is not necessary to make tradeoffs, such as comfort versus performance or agility versus stability. While the car is quiet and smooth during cruising, the driver feels confidently in control during emergency or aggressive handling maneuvers.

CVRSS 2.0 ENHANCEMENTS
New with CVRSS 2.0, the system calculates the steering wheel velocity by using the steering angle sensor. This improves the transient roll control characteristics of the DTS by stiffening the outside dampers in compression and stiffening the inside dampers in rebound. As a result, when a driver quickly turns the steering wheel, the system commands the ideal damping at the inside and outside wheels to slow the roll of the body.

Another enhancement uses the lateral acceleration signal to improve vehicle lateral support by stiffening the outside dampers in compression and the inside dampers in rebound, effectively "wedging" the car, or decreasing lateral load transfer in a turn. This means that as the vehicle reaches steady state, the damper settings become optimized to maintain traction with the road.

CVRSS 2.0 also features stability control interaction. When StabiliTrak is activated, the front corner with the brake applied is stiffened in compression, while the opposite rear corner damper is stiffened in rebound. This reduces the "dipping" of the body and thus improves handling.

FOUR-STAGE VALVING
DeVille, DHS and DTS all come equipped with four-stage, shock-absorber valving for improved body motion control without sacrificing isolation. The new four-stage technology is used in all four DTS shock absorbers and in the front shock absorbers only in DeVille and DHS.

Squeeze-cast aluminum road wheels provide the most mass-effective wheels available with superior surface finish. DeVille and DHS are equipped with Michelin blackwall all-season radials - size P225/60SR-16 - which provide very low rolling resistance for excellent fuel economy. White sidewall radials are offered as an option. DTS is equipped with Goodyear Eagle LS P235/55HR-17 blackwall all-season performance radials.

DeVille�s anti-lock brake system, traction control and StabiliTrak systems are combined in a new Delco Electronics-Bosch 5.3 design that is smaller and lighter than the 5.0 design it replaces. A significant new feature with this system is electronic brake distribution. In place of a fixed front-to-rear distribution of braking effort for all vehicle loading and operating conditions, the electronic approach uses wheel-speed sensors and hydraulic controls to adjust and optimize distribution dynamically. Stopping distances are shortened, especially in the heavily loaded condition, when more rear brake effort is desired. Electronic brake effort distribution also improves handling during braking-while-turning maneuvers.

STABILITRAK BENEFITS
StabiliTrak 2.0, an improved version of the most advanced integrated stability control system in the world, is standard in DTS and offered as an option on DeVille and DHS. The improvements on this enhanced version include side-slip rate control and active steering effort compensation.

Introduced on three performance-oriented Cadillac models in the 1997 model year, StabiliTrak provides an important safety advance by helping the driver maintain control during emergency or evasive maneuvers. StabiliTrak works by comparing the driver�s intentions (indicated by steering wheel position) with how the vehicle is responding. Three key sensors keep the ABS and traction control computer informed: one reads steering wheel angle, another reports the vehicle�s lateral acceleration and the third measures yaw rate (rotational velocity about a vertical axis through the car�s center of gravity). Information is also gathered from vehicle speed.

If the vehicle�s dynamic response does not agree with the direction the driver is steering, StabiliTrak goes to work by selectively applying the individual front brakes to help keep the car on the intended course. If the car is slipping wide of the desired path in a turn, applying the inside brake helps the DeVille turn tighter. In case of diminished traction at the rear causing the tail of the car to drift wide, activating the outside-front brake gently nudges the car back in line. StabiliTrak is automatic and requires no additional driver action. In most cases, the driver probably won�t even notice the helping hand from this technically sophisticated system.

Respected car critics have called StabiliTrak one of the greatest active safety advancements since four-wheel anti-lock brakes. Unlike stability control systems from other manufacturers, Cadillac�s system maintains the driver�s ability to apply throttle in StabiliTrak maneuvers.

STABILITRAK 2.0
StabiliTrak 2.0 adds the additional calculation of side slip rate. This means that the system now also analyzes data from the lateral acceleration and yaw rate sensors to determine side slip. If the system determines that the vehicle has lost lateral traction at both front and rear axles, it will apply the front brakes to slow and stabilize the vehicle until lateral traction and desired yaw rate have been restored. It can also improve vehicle stability during the transient conditions between vehicle understeer and oversteer. This new computational method is particularly effective on slippery surfaces, often bringing the car back into control without the driver realizing that there was a momentary loss of cornering adhesion.

Another feature of StabiliTrak 2.0 is active steering effort compensation. Starting in 1998, Cadillac was the first in the industry to coordinate steering assist with stability control. During low-traction or emergency-maneuver situations, StabiliTrak commands the Magnasteer system to adjust the level of power assist in order to achieve a consistent steering feel. With the enhanced version of StabiliTrak on the 2000 DeVille, active steering effort compensation also is triggered by ABS and traction control operation. Combining steering assist level with stability control is unique to Cadillac, and it was achieved solely through software calibrations with no added hardware, cost or mass.


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