chris j vurnis

After driving an Infiniti I30 clone in Asia a few months back, I am curious about how to change the overall gearing of the automatic.

Judging speed and RPMs, every gear seemed to be about 15% shorter than on my car.

Well actually, it wasn't a 3.0 liter VQ.
It was a 2.0L VQ 6 cylinder engine... exactly like the Maxima engine but downsized but with a variable intake.

With a rear drive car, you can just change the rear axle ratio.
Or even in a front drive 5 speed manual, one could find different gear sets.

But how would it be possible for a front drive automatic?
Could one change the size of the input shaft or torque convertor or perhaps the drive shafts?

I figure if they make a 2.0, 2.5, and a 3.0 liter VQ, there must be some external variable that they would use to change the gearing so they could use the same transmission for all three models.

Any ideas? I'll try to scout this out to see how they do it.

chris j vurnis

Well, I just got my Internet search done.
Basically I compared the specs for a Nissan Cefiro which is a clone of the Infiniti sold here which is of course a clone of the maxima.

Just as I suspected, the automatic transmission ratios for all models with either the 2.0, 2.5, and 3.0L VQ are the same. But the "final drive" ratios are different:

the 2.0L model gets a 4.4 ratio, the 2.5L gets a 4.0 ratio, and the 3.0L gets a 3.8 ratio.

So it wasn't just speedometer error -- there really is a 15% gear difference from the 2.0L to the 3.0L.

So why am I interested in this?
Well, it's just that much more torque multiplication to the wheels.
It's just that much more acceleration around an intersection without having to stomp it down to 1st. For overdrive; being the only gear where the torque convertor locks up at cruising speeds, the engine needs less torque output to keep the same speed -- which should make it more efficient. Basically, more acceleration without having to generate more power. And I could get sort of 5-speed like acceleration with the convenience of an automatic.

I figured its just something different to throw out there as an idea. Finish it off with a nice torque aftermarket convertor and a Variable intake and it should be nice...

EZEMaxima

BUT...... would the final drive gear fit a 4th gen Maxima from a 2.0l or even a 2.5l?

mzmtg

iTrader: (11)

Almost certainly.

Lime

interesting....
How hard would it be to get a hold of this stuff and install it?

Stephen Max

iTrader: (59)

Smaller wheels accomplishes the same thing. I understand why you may not want to do this for aesthetical reasons, though. Big wheels seem to be popular today.

mzmtg

iTrader: (11)

Smaller wheels will cause speedometer error. They may also interfere with proper ABS operation.

And "aesthetical" isn't a word.

Stephen Max

iTrader: (59)

It's not? Better tell dictionary.com that.

2 entries found for aesthetical.


--------------------------------------------------------------------------------

AEsthetic \[AE]s*thet"ic\, AEsthetical \[AE]s*thet"ic*al\,a. Of or Pertaining to [ae]sthetics; versed in [ae]sthetics; as, [ae]sthetic studies, emotions, ideas, persons, etc. -- [AE]s*thet\"ic*al*ly, adv.
Source: Webster's Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc.


--------------------------------------------------------------------------------

aesthetical

adj : concerning or characterized by an appreciation of beauty or good taste; "the aesthetic faculties"; "an aesthetic person"; "aesthetic feeling"; "the illustrations made the book an aesthetic success" [syn: aesthetic, esthetic, esthetical] [ant: inaesthetic]
Source: WordNet ® 1.6, © 1997 Princeton University

Stephen Max

iTrader: (59)

Large wheels cause speedometer error, too, but people don't seem to be worried about that. And I don't see how wheel diameter would affect ABS operation.

chris j vurnis

Well, I got some wrong info in here.
The final gear ratio for the 3.0L is a 3.6 instead of 3.8 that I wrote in my other post.

I found that in the service manual. Anyway, the final drive gear is built into the transmission. I suspect changing it won't be hard since I believe they use the same transmission for the smaller displacement VQ engines with exception of the final drive gear.

darksands

Wow.. Ive been wondering about changing the gear ratio's for the longest time. I just didnt know how. I wish I could just plug in a computer and change it like in GT3. Oh well, If ya guys figure it out, it will be another great modifications for the Auto's.