7-speed Transmission Info
#1
7-speed Transmission Info
Quoted from NNA:
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.
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.
#3
#7
For smoother downshifting, Downshift Rev Matching (DRM) mimics the heel-and-toe maneuver used by skilled drivers during manual transmission downshifts.
In all honesty, I know a lot of folks who b**ched and moaned about Nissan/Infiniti's 5A/T for the past few years because it was short a few ratios compared with competitors. However if you ask me, even the current 5A/T is ahead of the curve in many areas. DRM alone was worth sacrificing a 6th gear for. Whoever wrote the programming for the 5A/T w/ DRM that first debuted in '05 deserves to be promoted. Ever drive a 7G-Tronic Merc w/o DRM? Good God that thing feels sloppy going into a corner. No wonder other manufacturers are finally catching on and implementing some sort of rev matching feature into their A/Ts. I also like how the Nissan/Infiniti A/T lets the driver do the shifting when the car is put into manual mode. If you want to bounce it off the limiter, go right ahead. I hate automatic boxes that shift at redline in manual mode. It defeats the purpose of a MANUAL mode. The fact that the new JATCO box now has 7 ratios to play with instead of 5 simply secures it's spot at or near the top if you ask me. Call me biased, but I think Nissan/Infiniti's JATCO TC automatics are some of the best sporty A/Ts on the market. The only thing Nissan/Infiniti has yet to get right is the "pull back to upshift/push forward to downshift" F1 style shift pattern that so far only BMW, Mazda and a few other manufacturers have gotten right.
On a side note, the revised programming of the CVT in the '09 Maxima has gotten rave reviews effectively silencing and addressing most of the complaints made about said type of gearbox in previous FWD Nissans. All Nissan/Infiniti needs to do is some fine tuning on their clutch pedals and they'll be all set in the transmission department. The '07 V36 Sedan shifter is already better than the shifters found in Infiniti's rivals over in Munich IMO. Kudos to Nissan/Infiniti for continuing to improve on a device often overlooked by many non-enthusiasts and catering to us gearheads for a change.
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#8
I prefer the F1 'pull shift up, push shift down', but its always easier to explain to people...
push up to shift up. pull down to shift down.
+1 on the DRM.... I was experimenting in a FX today.... 7th gear at 45mph... gotta hit the paddle FIVE TIMES to shift into lowest avail gear for max power.... 7->6->5->4->3->2
I vote let DS just skip gears for you
push up to shift up. pull down to shift down.
+1 on the DRM.... I was experimenting in a FX today.... 7th gear at 45mph... gotta hit the paddle FIVE TIMES to shift into lowest avail gear for max power.... 7->6->5->4->3->2
I vote let DS just skip gears for you
#9
#10
How would they reduce cost? This transmission is going to be used in almost the entire lineup, similar to how the 5 speed was used in almost every vehicle offered.
Also, dual clutch systems generally don't offer the smooth shifts the majority of the segment is looking for. That is why Audi/BMW/Mercedes/Lexus also continue to use torque converters.
Smooth shifting dual clutch trannies will go through their clutches relatively q uickly.
Also, dual clutch systems generally don't offer the smooth shifts the majority of the segment is looking for. That is why Audi/BMW/Mercedes/Lexus also continue to use torque converters.
Smooth shifting dual clutch trannies will go through their clutches relatively q uickly.
#11
Originally Posted by Mike@RiversideInfiniti
That is why Audi/BMW/Mercedes/Lexus also continue to use torque converters.
The only downside to the DSG (other than my left-leg being bored) is some abruptness at launch that needs to be compensated for by taking up the throttle in a controlled manner similar to what you have to do when driving a true manual. Beyond that, it's smooth, seamless, and shifts awfully fast.
#12
3.133?
Originally Posted by Mike@RiversideInfiniti
Expect around 2400-2600 for 80mph; FX35 gearing should be equivilent to the Sedan; they have in the past. Final drive will be different to account for tire diameter.
Presuming roughly the same tire diameter as the 2008 G35 Sedan, that would ( rather strongly ) imply that Infiniti has chosen the 3.133 final drive. With 0.77 top \ seventh gear, I calculate roughly 2650 RPM at 80 with that final drive.
That would be my vote.
Hope you are correct!
- Ray
Waiting, still . . .
#13
Originally Posted by rayainsw
Based on . . . ?
Presuming roughly the same tire diameter as the 2008 G35 Sedan, that would ( rather strongly ) imply that Infiniti has chosen the 3.133 final drive. With 0.77 top \ seventh gear, I calculate roughly 2650 RPM at 80 with that final drive.
That would be my vote.
Hope you are correct!
- Ray
Waiting, still . . .
Presuming roughly the same tire diameter as the 2008 G35 Sedan, that would ( rather strongly ) imply that Infiniti has chosen the 3.133 final drive. With 0.77 top \ seventh gear, I calculate roughly 2650 RPM at 80 with that final drive.
That would be my vote.
Hope you are correct!
- Ray
Waiting, still . . .
And yes....waiting still.....
#14
Originally Posted by opus
Why don't Nissan/Infiniti just slick a DCT (DSG) type transmission in? No more traditional manuals or automatics. They could reduce inventory cost.
A DSG-like transmission as an additional option would be great though. But this 7-speed automatic seems more than adequate.
PS. Like Mike asked, how would that reduce costs? It surely hasn't reduced costs for the other manufacturers.
.