2009 Infiniti FX50

Chassis and driving dynamics

Under the FX’s assertive exterior is an equally advanced body structure. FX uses the rigid FM platform architecture used on the Infiniti G37 and EX37. The FM platform offers sports car-like front-to-rear weight balance for exceptional handling. 

Additional development was undertaken to reduce weight and enhance body strength. For example, the FX’s aluminum front and rear door panels, which have the same strength and stiffness of conventional steel doors, are 20 kilograms lighter (total for all four doors), allowing the FX to maintain a power-to-weight ratio that is among the best in class.

The new FX’s body is also 1.6 times more resistant to twisting and 3.4 times more resistant to bending than the previous generation FX design. As well as boosting handling, the rigid body benefits to NVH performance.

The new double-wishbone front suspension design, similar to that found on the G37 and EX37, replaces the previous generation FX’s front strut-type suspension. The suspension’s upper and lower A-arms help provide superior control of a wheel’s motion, especially when the suspension compresses and extends, providing more travel than the previous strut design. The net result is a better ride and improved handling.

At the rear, FX uses the multi-link design from the previous generation, refined to weigh less and provide more wheel travel – again for improved ride and handling. A lightweight, high-strength steel rear subframe isolates the FX’s body and its passengers from road noise and vibrations. Its compact design benefits rear passenger and load space. Large diameter anti-roll bars can be found front and rear.

The suspension system also incorporates special dual flow pass shock absorber technology with rebound springs for responsive yet comfortable ride and firm, tight handling.

FX50S and FX37S suspension feature standard active Continuous Damping Control (CDC) system with special electronically controlled shock absorbers. Unlike conventional fixed damping force shock absorbers, suspension with active CDC takes the input from a variety of sensors and continuously alters the damping of the dampers to provide optimal ride and handling. The system features a driver-selectable switch with two settings – Auto and Sport – allowing the driver to control the valving levels.

FX50S’s standard Rear Active Steer system is the first of its kind available in an SUV. Unlike passive rear steering systems, this design features precise, electronic motor-driven control to turn the rear wheels up to one degree, helping generate a nimble steering response at low speeds and enhance stability at high speeds.

Rear Active Steer moves the FX50S’s rear wheels in accordance with steering input and vehicle speed, rather than passively following the front wheels. The result is a vehicle that is able to change direction with improved quickness, precision and stability.

The new FX maintains its small turning radius (5.6m) despite its larger wheel and tyre package. Infiniti engineers focused on improving steering feedback from the advanced speed-sensitive rack-and-pinion power steering system and reduced play in the steering mechanism for more direct vehicle response to steering input.

An essential element of its crossover role is the adoption of Infiniti’s ATTESA E-TS (Advanced Total Traction Engineering System for All Electronic Torque Split) All-Wheel Drive system which uses an active torque distribution management system with an active centre clutch for smooth starts, greater grip and better manoeuvrability on slippery surfaces without compromising the vehicle’s rear-wheel drive performance characteristics on dry roads.

By constantly adjusting the power – sending anything from 50 per cent to the front, to up to 100 per cent to the rear – the system generates greater control without sacrificing sportiness and true performance dynamics.

Unlike permanent 4x4 systems, which deaden the steering feel and dull the driving dynamics, the electromagnetic torque transfer at the heart of ATTESA E-TS Intelligent AWD’s system permits an element of oversteer for a more sporting drive.

Intelligent All-Wheel Drive works with Electronic Stability Program (ESP) and the Limited-Slip Differential, constantly shifting torque as FX encounter changes in the road conditions when, within milliseconds, it will apportion power to the wheels with the most grip.

The system is most active off the highway. As FX navigates snow, sand or mud, power is continuously apportioned to the wheel or wheels with the best traction.

Secure braking performance is provided by ventilated disc brakes front and rear with Intelligent Brake Assist (IBA) and Electronic Brake force Distribution (EBD). An integral part of Intelligent Cruise Control (standard on FX50S, optional on FX37 and FX37S), when IBA detects that a collision with a car in front is imminent it first warns the driver and then brakes the car itself.

The braking system features four-piston opposed front/two-piston opposed rear calipers, similar to those found on the new Infiniti G37S, and large brake discs (355x32 mm front/350x20 mm rear). Brake dimensions and high thermal capacity have been tailored specifically to European driving needs, providing a secure and stable feeling at very high speeds and high deceleration rates.

FX50S and FX37S feature standard metallic-finish six-spoke cast-alloy 9.5J x 21-inch wheels made by Enkei. These wheels are created using a special type of ultra-lightweight casting and are as light as a competitor’s 18-inch wheels. They are mounted with 265/45R21 performance tyres. FX37 has 20-inch alloy wheels with all-season tyres as standard.

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