7 Speed transmission - Nissan North America

[williammoses]

Nissan North America posted this article on the Infiniti five and seven speed transmissions. Although the article appears to bear a heavy hand from Nissan's marketing department, I found in it some useful technical discussion. I have copied the full article, but I am posting the link to it also: http://g35driver.com/forums/g35-sedan-v ... -info.html.
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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.

[Hono]

Splendid, a recent thread dealing with the only irksome thing about our new 2011 EX...

Still don't have enough miles (<750) to let the dogs loose but harbor no doubt whatsoever that Infiniti needs to do some acoustics tuning or sound deadening on their new 7-speed automatic mated to the 3.5L engine in the 2-wheel drive EX...

Can't feel the shift points, but most certainly can hear them. When dawdling along in stop and go traffic the sound emanating from that new 7-speed is highly reminiscent of the Dynaflow transmission in my grandma's old (circa 1950's) Buick Roadmaster. So much so that it instantly conjures up scary memories of that old dear careening down the road terrorizing both the local denizens and her favorite grandson sitting beside her...

IMHO, Infiniti's reincarnation of the "Dynaflow sound" certainly does little to enhance the EX's sporting pretentions. Moreover, it is quite embarrassing to boot---the Buick Dynaflow transmission was nicknamed "Dynaslush" and "Dynaflush". The former because of its leisurely performance and the latter because its sound mimicked a sanitary appliance popularized by Thomas Crapper & Co. in the late-1800's...

Not quite sure where the problem lies but suspect it has something to do with a series of very quick low-RPM shifts to obtain the best possible MPG. The 5-speed automatic on our G35 was both quieter and better sounding. It was also every bit as smooth. Hopefully once break in miles are complete a return to my normal driving style will temper that WWOOOOOOSSSHHHH sound somewhat. If a heavier foot on the throttle isn't the cure, guess I'll have to find out if the EX's audio system actually works...

[williammoses]

Hono:
The transmission may still be adapting to your driving inputs. It seemed to take a couple of months for my 2011 EX35's 7 speed transmission to adapt to mine. The transmission has become smoother and more responsive than it was at first. I have come to believe the transmission is one of the vehicle's best features.

[Hono]

Good points williammoses. In the delivery dog & pony our salesman mention the car "learns". Fear ours will grow up horribly befuddled since my wife and I share wheel time but have polar-opposite driving styles. Hopefully whoever wrote the "adaptation" software allowed for that sort of multiple driver situation. BTW, this "adaptation" thing is not new. Seem to remember it being around since at least the mid-80's...

Unfortunately, transmission performance is not the issue. Have no problem whatsoever with smoothness---I can't even pick out the shift points while driving. My issue is the resonance the transmission makes at lower speeds. That WOOOOOOSSSSHHH sound has not been a acoustic reflection of state of the art transmission technology since the 1950's and early-1960's. Or perhaps other OEMs are better had masking transmission sounds than Infiniti? All things considered, given the choice I would opt for the noticeably quieter and better sounding G35 5-speed over that "flush the toilet" sounding 7-speed in the 2011 EX...

BTW, didn't mention it in my earlier post but have also noticed a minute bit of "turbo lag feel" when needing sudden power after the transmission gets into 4th gear (or wherever it ends up) in the 20-30mph range. That is most likely due, as one would expect, to a lack of torque at lower RPM in a high gear. Pretty sure that too will pass with more miles on the clock and a much heavier foot on the throttle after break in...

[Hono]

BTW williammoses, just noticed your Alexandria venue. Use to live in the Eastport section of Annapolis and made quite a few sorties to Alexandria in quest of W, W & S...

Unfortunately, like Eastport much of Alexandria is pretty low lying and the latest NHC advisory on Irene just posted (5 PM EDT) doesn't look very good. Hopefully you are above any storm surge up the bay or aftermath Potomac floods. If not, hope you are well along in plans to get you, yours and that EX out of the area or to higher ground...

Best of luck to you, and any other board members, in similar situations... Hono