Viscous Coupler: Description
WARNING: This page is about a different car, the 2004 Chrysler Pacifica. However, it is still accessible from the selected car via links, so may be relevant.
The heart of the all-wheel drive system is the inter-axle viscous coupling and bi-directional overrunning clutch. Under normal driving the vehicle retains predominantly front wheel drive characteristics. The all-wheel drive takes effect when the front wheels start to slip. Under normal level road, straight line driving, 100% of the torque is allocated to the front wheels. The viscous coupler allows more torque to the rear wheels in accordance with the amount of slippage at the front wheels. The variable torque distribution is automatic with no driver inputs required.