5.12.2003
Premiere for Integrated Chassis Control in new Astra

The new Astra not only brings a dynamic look to compact cars, the agile suspension also delivers the promise of the progressive design.

With the optional IDSPlus (Interactive Driving System) adaptive chassis system, the third generation Astra opens a new dimension of suspension performance with an optimum balance of driving comfort and active safety. Opel/Vauxhall's new compact is the first car in its segment with an integrated chassis control network. In addition to ABS and ESPPlus, the network also includes CDC (Continuous Damping Control), which is a major component of the IDSPlus system.

This is the first time CDC, usually reserved for luxury or exclusive sports cars, has become available to so many customers. For the first time Astra drivers can activate a special sport mode at the touch of a button. This selects suspension settings for the enthusiast-driver, adapts the steering and accelerator response and, with automatic and Easytronic transmissions, adjusts the shift points higher up the rpm range.

Front suspension: numerous improvements to proven concept

Impressive agility and a high level of safety were the development objectives for the new Astra's IDS suspension. With a wheelbase of 2614 mm it features further developed McPherson struts with lateral control arms attached to a hydro formed subframe at the front. The new strut mounts are decoupled, effectively reducing noise and vibration, and for improved response, the banana-shaped coil springs provide enhanced compensation of the lateral forces acting on the shock-absorber piston. In order to achieve equally good ride-comfort for all engine variants, the spring-rates are adapted to the front axle-load in 30-kg-steps. The weight-dependent spring rates allow an almost constant ride-frequency of the front axle across the whole engine range – from the 1.4 TWINPORT to the 2.0 turbo or the 1.9 CDTI – despite up to 200 kg variation in axle-load.

Flexible manufacture of the new steering knuckle allows a greater difference in tread-angle for improved steering response, contact with the road and self-centering. Thanks to the new production method, Opel/Vauxhall can offer two lengths of steering arms. A more direct steering ratio (14:1 instead of 15:1) is available for the Astra with sport-chassis and 15-mm lower body.

The fuel saving electro-hydraulic power-steering (EHPS) is map controlled. The most important parameters are vehicle speed and steering input, the optimum power assistance for every driving condition is provided. By selecting the optional sport-mode, the steering map is shifted towards "direct" at the push of a button.

Rear suspension: multiple variations of torsion beam design

At the rear the new Astra features a specifically adapted torsion beam with double-walled, U-shaped profile at the rear. In the new Astra this design combines all the advantages of a conventional torsion beam axle – such as minimum space requirements – with low weight and consistent camber control. It can also be precisely tuned to the specific requirements of different versions within the model range.

The major difference to other torsion beam designs is the patented "magnetic-arc" welding process used to attach the beam with the control arms. This production-technology makes possible different thickness of the torsion beam (anti-roll bar effect) and different attachment angles between the beam and the trailing arm (self-steering control). The advantage is the adjustment of roll-rate and roll-steer to individual engines, vehicle weights and body styles (e.g. station wagon with high payload), and electronic systems like ESP.

This adaptability is used comprehensively in the Astra. Additional benefits include improved stance and more interior space from the wider tread (up to 32 mm), and improved noise and vibration attenuation from the larger (70 mm) bushings. Intensive development of the beam's twisting characteristics also led to further improved driving stability as well as more agile self-steering.

The space-saving layout of the rear axle also helped the engineers to achieve a low center of gravity for high agility. Thanks to the compact design, the fuel tank fits between the wheels, enabling lower positioning of the seats.

Agile: Sport set-up by the touch of a button

Additionally, with the IDSPlus system, the Astra driver can switch to a firmer, more agile sport mode at the touch of the SportSwitch in the cockpit; this regulates the damping characteristics, accelerator response and the characteristics of the electro-hydraulic steering. With automatic transmission or Easytronic, the shift points are raised to higher rpm levels, for a sportier driving style. For special requirements the latest generation ESPPlus can be deactivated.

Opel engineers have improved the efficiency of ESPPlus and ABS by the intelligent networking of sensors and controlling programs, and added a series of further functions, including:

- Understeer Control Logic
- Hill-Start Assistant
- Trailer Stability Assist
- Deflation Detection System
- Tire Pressure Monitoring System