
All-wheel drive system supplier Haldex has introduced its latest iteration in the new Saab Turbo X and 9-3 Aero XWD vehicles. XWD strands for Cross-Wheel-Drive and is technically called Haldex version 4.0. Its introduction has generated some excitement amongst general consumers and tuning enthusiasts. Haldex has been riding the high wave with their XWD release as it was recently reported that they won a contract to develop a system for Hyundai. We have yet to see the new all-wheel-drive offering hit consumers in order to better understand its potential under extensive abuse though. However, the wonder that is YouTube has provided us with video of the Saab Aero XWD in action during a Saab comparison test drive event. Haldex has also supplied a wealth of information detailing the elements of their 4.0 system.
The main components of the new Haldex system are the Power Take-Off Unit (PTU), Limited Slip Coupling (LSC) and eLSD (Electronic Limited Slip Differential). The PTU is the final drive unit at the front of the vehicle that transmits power to the front wheels and sends power down the driveshaft to the rear wheels. It is not a Haldex design, but is required to adapt the system to a front-wheel drive vehicle. The LSC sits at the rear of the vehicle in-line with the driveshaft. It controls the torque split between the front and rear wheels of the vehicle. The LSC sends torque to the eLSD that sits between the rear wheels. The eLSD transfers torque to the two rear wheels. Follow the jump to continue reading more about the system.














