QX4's Innovative All-Mode 4WD System Keeps Infiniti On Cutting Edge Of All-Wheel Drive Design And Performance


Technically advanced yet simple to operate - two hallmarks of the Infiniti QX4s unique All-Mode 4WD system when it was introduced in 1997 and which keep it unchallenged two years later as the most sophisticated all-wheel drive design available in North America today.

Derived from the advanced ATTESA E-TS all-wheel drive system used in the high-performance Japanese-market Nissan Skyline GT-R sports coupe, the QX4 system was developed to enhance traction and stability in everyday driving conditions, while also performing equal to or better than traditional 4WD systems in rugged off-road conditions.

The key advantage of the All-Mode design over conventional systems is its combination of fully automatic, seamless operation, requiring no driver intervention and driver override, yet still allowing manual control as desired.

The system offers the driver the choice of 2-wheel drive, 4-wheel drive or "automatic" setting, in which the system instantly distributes torque to the front wheels - in the precise amount that is required to restore traction only as required - and then returns to rear-wheel drive operation.

The result is optimal traction in all conditions, while improving fuel economy and enhancing cornering capability. It is a totally flexible system that makes "average" drivers feel comfortable, while at the same time rewarding the driving enthusiast.

All-Mode 4WD System Hardware

The heart of the All-Mode 4WD mechanical system is a wet multi-plate clutch in the center differential. Managed by an electronic control unit, the multi-plate clutch precisely and instantly apportions the right amount of torque for the driving conditions to the front and rear axles.

A critical aspect of the system is that the multi-plate clutch provides infinitely variable torque transfer as opposed to the limited pre-set "steps" of adjustment typical of other systems. The amount of torque apportioned to the front wheels depends on two factors.

First is the amount of wheel slippage detected by the control unit, such as may occur when the vehicle is traveling on a dirt or icy road (wheel slippage is determined as the difference in speed between the front and rear driveshafts). The second factor is throttle opening. All-Mode 4WD (when in the AUTO setting) also transfers torque to the front wheels during initial acceleration (more throttle opening means more torque is distributed to the front wheels).

For rigorous off-road conditions, an optional limited-slip rear differential (LSD) further enhances traction. LSD provides even greater traction and control in the most challenging driving conditions.

All-Mode 4WD System Software

Governing the QX4's All-Mode 4WD hardware is an advanced computerized control unit. This unit gathers information from front and rear driveshaft sensors (to determine wheel slippage), a throttle position sensor, an engine rpm sensor, a transfer unit lever selector, and the Anti-lock Braking System (ABS) control unit.

The control unit continually compares the data and automatically selects the right amount of power to be transferred to the front and rear axles to achieve maximum traction. In the event that front and rear wheels are slipping, the greater amount of torque is directed to the axle with the least amount of slippage.

A pair of controls provide simple and effective operation: An instrument panel-mounted drive mode display switch used to select automatic or manual operation, and a floor-mounted lever which engages and disengages low range (4Lo).  This allows drivers the opportunity to choose the drive mode most appropriate for a particular driving surface.