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May 24, 2012, 06:05:37 AM

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CARfaq.org > Forum > Campus > Infiniti > G '02-09-Infiniti > General Discussions-G Infiniti > 7spd Auto for G?
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Author Topic: 7spd Auto for G?  (Read 3071 times)
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Mike_TX
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Re: 7spd Auto for G?
« Reply #15 on: June 02, 2008, 10:45:58 PM »

Well, here's one boy who hopes Infiniti uses more common sense with the 7-speed than they did with the 5-spd. I'm sure it's just me, but I couldn't drive the G35 smoothly. If I had to accelerate some to squirt past some slower traffic, it would kick down so hard that the engine would scream and people would look at me like I was some kind of boy racer or something. It was just entirely too hyper for me.

I drove an '08 for a day and it seemed a little better, but still too jerky-jumpy for my kind of spirited driving. I move on out, but I like to torque through my traffic moves, not scare everyone to death with overly-dramatic downshifts at unexpected times. I like more finesse.

In that vein, I am hoping the 7-speed allows more flexibility in gearing choices, and less abrupt downshifts. But Helldorado's right - that's some short-ass first gear. They need to team it up with a higher-geared rearend to tame it some, and with 320+hp, they don't need to gear it like a VW Rabbit anyway.

Especially in the M, it needs to have a sedate cruising gear. My LS460 turns 1950 rpm at 80 mph, and gets 30mpg on the road, yet it still hauls buns when needed. But my '06 M45 buzzed like a Pontiac 4-banger at 80, and sucked the gas, too!

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Re: 7spd Auto for G?
« Reply #16 on: June 02, 2008, 10:58:40 PM »

Well the 7th – 0.77 vs 5th .84 is significant, but it isn't earth shattering.  As I've said before I think this transmission was obviously set up for maximum performance and improved economy, but not maximum economy by any means. With the ratios provided, I wouldn't think it'd be out of the ordinary to see it shift from 7th all the way down to 4th if you really push it on a freeway pass, but I think 6th or 5th would be more common for routine passes.
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Re: 7spd Auto for G?
« Reply #17 on: June 02, 2008, 11:08:03 PM »

They obviously could have put a lower final gear in it, similar to Lexus whose gear ratios I pulled up for comparison:

First Gear Ratio        4.60
Second Gear Ratio    2.72
Third Gear Ratio        1.86
Fourth Gear Rato      1.46
Fifth Gear Ratio        1.23
Sixth Gear Ratio       1.00
Seventh Gear Ratio   0.82
Eighth Gear Ratio      0.69

Final Drive Axle Ratio 2.94

Infiniti 7-speed AT:

1st – 4.92
2nd – 3.19
3rd – 2.04
4th – 1.41
5th – 1.00
6th – 0.86
7th – 0.77
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Re: 7spd Auto for G?
« Reply #18 on: June 02, 2008, 11:20:35 PM »

As I said, the key will be the final drive ratio.  That's what makes it all come together.  Everything else is conjecture until we know.
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Re: 7spd Auto for G?
« Reply #19 on: June 02, 2008, 11:45:42 PM »

Quote from: Mike_TX on June 02, 2008, 10:45:58 PM
Well, here's one boy who hopes Infiniti uses more common sense with the 7-speed than they did with the 5-spd. I'm sure it's just me, but I couldn't drive the G35 smoothly. If I had to accelerate some to squirt past some slower traffic, it would kick down so hard that the engine would scream and people would look at me like I was some kind of boy racer or something. It was just entirely too hyper for me.

I took my FX in for service a couple of days ago and that was the biggest complaint I had about the loaner.  I couldn't seem to successfully pass people with ease.  It was all or nothing.  I'd massage the throttle and the G would weeze past the slower vehicle.  So next time I put a little more foot down, and as you described, the auto would kick down a couple of gears and the G would take off like a bat out of hell.  What happend to "Acceleration Swell".  I'm sure it was a combination of gearing and the fact that was used to the quite piggish acceleration of the FX.  Like you, though, I like to be able to ease that right foot and use the torque (and proper gearing) to glide past slower vehicles.
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Re: 7spd Auto for G?
« Reply #20 on: June 02, 2008, 11:52:54 PM »

I would also add to your assessment: that the vehicle supposedly learns your driving style and reacts accordingly.  So if its a loaner vehicle that probably gets dogged out all the time, it probably will react more aggressively, as thats what it has been subjected to and is "learned" behavior at this point.  I have no trouble passively passing cars on the highway, but I'm used to the car, and I don't drive like a maniac 90% of the time.
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Re: 7spd Auto for G?
« Reply #21 on: June 03, 2008, 12:03:56 AM »

Quote from: helldorado on June 02, 2008, 08:10:10 PM
The larger the number the "shorter" the gear.  Shorter gears equal higher torque multiplication to the wheels, which equal higher acceleration (after mechanical losses, physics ya know) but lower top speed at your rpm limit.

With such a short first gear, they're either going back to a taller FD ratio, like the 3.358 or first gear will top out somewhere around the low to mid 20 mph range with the current 3.700 they're using and 7500 rpm redline.

I have the current 5AT with the 3.917 FD and with a 7100 rpm rev limiter, hit redline around 27 mph IIRC and I hit redline in 2nd around 56.

Thanks for the pretty-understandable response. Damn physics.
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Re: 7spd Auto for G?
« Reply #22 on: June 03, 2008, 12:13:47 AM »

Quote from: Mike_TX on June 02, 2008, 10:45:58 PM
Well, here's one boy who hopes Infiniti uses more common sense with the 7-speed than they did with the 5-spd. I'm sure it's just me, but I couldn't drive the G35 smoothly. If I had to accelerate some to squirt past some slower traffic, it would kick down so hard that the engine would scream and people would look at me like I was some kind of boy racer or something. It was just entirely too hyper for me.

I drove an '08 for a day and it seemed a little better, but still too jerky-jumpy for my kind of spirited driving. I move on out, but I like to torque through my traffic moves, not scare everyone to death with overly-dramatic downshifts at unexpected times. I like more finesse.

In that vein, I am hoping the 7-speed allows more flexibility in gearing choices, and less abrupt downshifts. But Helldorado's right - that's some short-ass first gear. They need to team it up with a higher-geared rearend to tame it some, and with 320+hp, they don't need to gear it like a VW Rabbit anyway.

Especially in the M, it needs to have a sedate cruising gear. My LS460 turns 1950 rpm at 80 mph, and gets 30mpg on the road, yet it still hauls buns when needed. But my '06 M45 buzzed like a Pontiac 4-banger at 80, and sucked the gas, too!

Mike

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I test drove the IS-F and since it has an 8 speed auto based of the LS'es it seems to perform/act similarly to what you mention. When i was on the test drive i was commenting to the salesman that "this car is MUCH quieter than my car at 90.. it feels like i'm doing 50, maybe". I forgot to look at the revs in the -F at > 80mph, was too busy enjoying the rest of the car. Needless to say, with regular driving at 80-90 the car (engine/transmission) barely felt like it was doing any work at all. The M feels like it's working a lot harder.
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Re: 7spd Auto for G?
« Reply #23 on: June 03, 2008, 02:14:53 AM »

The M is a heavier car with a larger engine and higher final gear... so what you said makes perfect sense.    That on top of Lexus' legendary soundproofing. 
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