IT STARTED BY STOPPING WITH ANTI-LOCKING BRAKES
Beginning with basic Anti-lock Braking System (ABS) technology, electronic control units have evolved from those that helped to prevent lockup during braking so the driver maintained steering control to more sophisticated systems. Today, ABS controls take information from a host of sensors, and that information enables advanced braking, traction, and stability-control functions for the 2008 WRX STI.
Super Sport ABS
Using input from a lateral g-sensor, a steering angle sensor (new for 2008), a yaw sensor, and a brake pressure sensor, Super Sport ABS can control the braking forces at each wheel independently. The system enhances straight-line braking and optimizes braking ability during hard cornering by helping to reduce understeer. In contrast, conventional ABS systems control the rear wheels as a pair, reducing the braking force to both rear wheels equally instead of independently.
Super Sport ABS works in conjunction with VDC and DCCD, and it is complemented by Electronic Brake-force Distribution (EBD) and Brake Assist.
EBD helps to reduce stopping distances and to improve stability by precisely controlling braking pressure between the front and rear wheels based on vehicle load.
Brake Assist analyzes the force and stroke on the brake pedal. If the control unit senses an emergency situation, the system increases hydraulic boost to provide enhanced braking, also activating the ABS system early if needed.
The WRX STI driver also can custom-tailor the level of dynamic intervention offered by VDC. Changes are made by pushing the OFF switch on the dashboard to the left of the steering wheel column.
VDC has three settings:
- VDC – the default setting, optimized for daily driving situations. There are no warning lights associated with this mode, which enables all controls for ABS, the Traction Control System (TCS), and VDC.
- Traction – set by holding in the VDC off switch, which turns the VDC warning light green. This setting is more performance-oriented, with less-aggressive stability control. Engine torque-reduction control is disengaged.
- Off – set by pushing the off switch once. This setting turns off stability control and the traction control functions for emergency situations, such as getting out of mud or snow. It leaves ABS and incline start assist active.