GT-R Technical Features PtIV: Transmission and all-wheel-drive system

Such is the depth of information supplied on Nissan's all-new GT-R (and the interest in those details) we've taken the step of publishing a series of Technical Features spotlighting the GT-R. Here's the fourth in our series -- Nissan's own overview of the GT-R's drivetrain

According to Nissan: Like the VR38DETT engine, the all-new GR6 transmission was developed exclusively for the GT-R. The maker claims the paddle-shift, six-speed twin-clutch gearbox is "highly efficient" and unlike a traditional torque converter equipped automatic transmission there is "minimum power loss so response and fuel economy is improved."

The general layout of the GT-R's drivetrain was explained in PTII of this series Packaging. Images hereabouts show the rear-mounted GR6 transmission and the transaxle in which it is housed.

Also shown here is a section through the GT-R's combined gearbox/transfer case/final drive assembly showing the configuration of the unit.

Nissan says the twin clutch transmission offers the combination of "exceedingly quick gear shift speeds" and "full automatic transmission" operation.

Two ranges are offered: A (automatic) and M (manual). Within those ranges, the driver is able to select from normal and R modes, with the Auto setting also offereing a Snow mode for slippery conditions. R is described by Nissan simply as "the sportiest setting".

In auto, the car changes gear automatically, "in the most fuel efficient manner". Nissan says higher gears are used whenever possible, ultilising the car's fat torque curve.

The carmaker says the car can be "driven in sixth gear for long periods at low speeds, and still offers good throttle response. Such docile behavior is at odds with most equivalently fast supercars and is one of the many unique aspects of this technology flagship."

In M range, Nissan claims the paddle shift gives "exceedingly quick changes" maintaining boost for strong acceleration. When Manual R is chosen the gearbox's computer control "predicts the driver's next gear change, based on throttle opening, vehicle speed, braking and other information."

Nissan's twin-clutch gearbox features separate clutches for the odd (1,3,5) and even (2,4,6) gears (as per VW's DSG system). When the car is running in an odd number gear, the adjacent even numbered gears are pre-selected and are ready to make the shift immediately in the sequential-shifting gearbox. Upon downshifting, a synchronized rev control 'blips' the throttle precisely to synchronize engine speed for extra-fast downshifts. Borg-Warner triple cone synchronizers are used.

Nissan claims shift times are less than 0.5sec in R mode.

The GT-R's transaxle positions the gearbox's input and output shafts diagonally. So configured, the gearbox is 'flatter' and as such the transaxle can be more compact and the car's centre of gravity lower.

MORE ON ALL-PAW
Nissan claims the GT-R features "probably the most advanced four-wheel-drive system on a road car ever used." A big claim!

Called ATTESA E-TS, the all-wheel-drive system is "naturally" rear-drive biased, however, up to 50 per cent of available torque can be distributed to the front wheels as conditions demand.

Says Nissan: "Special computerised control automatically alters the front/rear torque split from zero torque at the front wheels, to 50 per cent of total torque. The control is varied continuously, as various sensors on the car measure speed, lateral and transverse acceleration, steering angles, tyre slip and other road surface and yaw rate."

The GT-R features an additional sensore over previous generations -- yaw-rate feedback control. This measures the difference between the target yaw rate (calculated from the steering angle) and the actual yaw rate (detected by yaw-rate and G sensors). According to the yaw-rate feedback control, the ATTESA E-TS's computer corrects front and rear torque values.

The four-wheel drive system includes traction control and Vehicle Dynamic Control (VDC-R), the GT-R's version of stability control. According to Nissan: "If off balance behaviour is detected -- such as sliding or skidding -- torque to the wheels will be altered to help stabilise the car." See specs below for VDC-R modes.

THE MAGIC TOUCH
Gearbox, VDC-R and suspension settings are all adjusted via the centre console mounted Set-up switches

There are three modes available for the transmission (see more above) and suspension. Featuring Bilstein DampTronic dampers, the suspension can be adjusted through: R (for high performance), Normal (sports) or Comfort (according to Nissan: for city driving to absorb road bumps, or for snow or rough roads).

VDC-R offers three settings also: Normal (Nissan: "for daily driving, controls brakes and engine output"), R-Mode ("for ultimate performance, utilizes AWD torque distribution for additional vehicle stability") and Off ("driver does not want the help of the system").