Torsen® Rear Differential

No sports coupe promising track performance would be caught without a Limited Slip Differential (LSD). The RC F comes standard with a Torsen LSD and offers the option of a new Torque Vectoring Differential (TVD).

The Torsen LSD offers high levels of traction performance, handling and driving control. Three key benefits stand out:

During straight-line driving, the Torsen diff controls the left-right speed differential to maintain straight-line stability. On entering corners, the coasting torque due to engine braking is distributed more to the outside wheel, to maintain stability. Mid-corner and on corner exit, the Torsen LSD distributes drive power according to the load on each rear wheel, to ensure high traction and maneuverability.

Torque Vectoring Differential

It would be no surprise that a car of the RC F’s track capability would offer torque vectoring to sharpen handling response. The news here is that the RC F uses the electronically controlled Lexus Torque Vectoring Differential (TVD). The TVD uses precisely controlled multi-plate clutches, rather than the vehicle’s brakes, to optimally distribute torque to each rear wheel whether or not the accelerator is pressed.

The design aim with a TVD-equipped RC F was to make full use of the vehicle’s yaw moment for turning posture so good that it would feel as if the steering angle and direction of the vehicle travel were solidly joined.

Electronic control and precision electric actuator motors that are adjusted in units of 1/1,000-second ensure the appropriate amount of torque is distributed to each rear wheel. TVD can generate torque transfer regardless of how large or small the engine torque is, creating a yaw moment around the center of gravity and realizing movement similar to the LFA with its 48:52 front/rear weight distribution.

The driver won’t notice the TVD’s seamless operation but rather will simply enjoy the feeling of using the accelerator pedal to help steer the car through corners.

Lexus meticulously tested the TVD at the Nürburgring and circuits in Japan to fine-tune its operation and cooperation with the new coupe’s Vehicle Dynamics Integration Management (VDIM) system.

The TVD distributes torque to match the conditions of the moment, ensuring dynamic response when negotiating S-bends, for example. It improves vehicle attitude in low-to-mid speed corners, providing more agile movement and a smaller steering angle.

In a series of S-bends, TVD provides exhilarating corner exit performance with no understeer. Crisp turn-in after hard braking is equal to highly skilled driving without a TVD. Even during deceleration, the TVD constantly controls the drive force to preserve agile and smooth turn-in.

The TVD has three operating modes, independent of the RC F Drive Mode Select function:

• STANDARD (default setting) provides an ideal balance of agility and firmness.
• SLALOM emphasizes nimble steering response and the agility of a smaller vehicle.
• TRACK emphasizes stability during high-speed circuit driving.

The RC F’s unique cockpit meter display shows the rear-wheel torque distribution as a bar graph within the tachometer and, if selected from the display menu, as two orange columns in the multi-information display.