Originally Posted by Nissan North America
Explaining the benefits of Infiniti’s new transmission
The target: create an automatic transmission with all the best features of a manual transmission. Here’s how Infiniti engineering gives drivers the best of both worlds.
The automatic transmission traditionally represented a compromise. It gave drivers the convenience of smooth, clutchless shifting, but it sacrificed the direct connection, driver control, and enhanced fuel economy of a stick shift.
Infiniti’s new 7-speed automatic transmission, available on 2009 FX35, FX45, G37 Sedan, G37 Coupe, and the upcoming 2009 M35 (rear-wheel-drive), takes the automatic closer than ever before to the feel and operation of a manual transmission.
No More “Slush-Box”
Slippage between the engine and transmission earned early automatics the nickname “slush-boxes.” The hydraulic clutch system for making gear changes could not operate as quickly or directly as a manual transmission’s mechanical clutch.
All modern automatics have a lockup torque converter, which limits slippage by creating a solid mechanical connection between the engine and transmission. For smoother operation over a wider range of operating conditions, newer designs vary the amount of converter lockup (from a 100% solid connection to a partial lockup condition).
Infiniti’s 5- and 7-speed transmissions use a multiple disc torque converter lockup design that allows the unit to “ease” into lockup, minimizing the shudder that can occur in single-disc designs.
While Infiniti is not the first manufacturer to vary the level of torque converter lockup, it has created an extremely wide available lock-up range with the new 7-speed transmission:
With the transmission in Drive, partial lockup is available in 2nd through 7th gears while full lockup occurs in 7th.
With the transmission in manual shift mode, both partial and full lockup are available in 2nd through 7th gears.
Some amount of lockup occurs at all throttle positions and at speeds greater than about 15 mph. The result? Infiniti's 7-speed transmission provides a more direct, solid-feeling connection than drivers typically expect from an automatic transmission.
In manual shift mode, a flick of the 7-speed’s shift lever makes the half-second gear change a reality.
Driver Control
For driving enthusiasts, one of the lures of a manual transmission is the control it gives them to select and maintain the gear they want. Several features of Infiniti’s new automatic transmission directly address this concern.
One of the foremost is manual shift mode. Consider this: for anyone other than a seasoned race driver, it generally takes more than half a second to make a smooth shift with a manual transmission — depress clutch, move shift lever, release clutch, apply throttle.
But in manual shift mode, a flick of the 7-speed’s shift lever (or available steering-column-mounted paddle shifters) makes that half-second gear change a reality.
For smoother downshifting, Downshift Rev Matching (DRM) mimics the heel-and-toe maneuver used by skilled drivers during manual transmission downshifts.
The 7-speed design targets both performance and fuel efficiency.
The 7-speed includes other features first seen on Infiniti 5-speeds, including:
Adaptive Shift Control, which enhances gear selection by using a lateral acceleration sensor to detect changes in the road (such as hills and turns).
Drive Sport Mode (DSM), which allows the driver to select a more aggressive shift pattern (automatic up- and downshifting at higher rpm).
Combined, these features allow any driver to enjoy quick, smooth shifts and gear choices that are appropriate to both the road and their desired driving style — some of the enthusiast’s main reasons for choosing a manual.
Enhancing Economy
Automatic transmission vehicles typically suffer a small penalty in fuel economy estimates when compared to their manual transmission counterparts. Infiniti’s 7-speed design targets not only performance, but also enhanced fuel economy:
The wide range of torque converter lockup operation maximizes engine efficiency (less power is wasted as slippage).
In previous 5-speeds, only 5th gear provided an overdrive ratio. Now both 6th and 7th gears are overdrive ratios, allowing the engine to operate at lower rpm during a broader range of highway speeds.
Owners may not understand the penalties they have paid in the past for the convenience of an automatic transmission. But whether drivers want “hands on” or “hands off” control, Infiniti’s new transmission will provide a satisfying driving experience.
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2010 k23
H&R sport springs / Spc rear camber arms / SSR SP1 / Berk cbe / Varis cf lip / Nismo S-Tune side skirts
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