^exactly. Also the 7 speed has a 3.92, not 4.92.

 

Thanks alot, so why would you want to go from 3.92 to 4.08? More high end?

Thanks it seemed a bit off thats why I asked, I just saw it on the first pages chart I knew something was off, I was a bit confused almost thinking about trading in my 6mt lol.

 

You would actually get more low end, hence quicker acceleration. It's not necessarily more low end torque, it just gets the rpms up quicker so you achieve higher torque quicker.

 

Where did you get that gear ratio? I thought the 7sp auto was like a 3.357.

 

I made up that little chart based on info from 2 different sources, I am not making any claims of accuracy to the numbers so with that said,,,, The first gear in 7at is supposedly 4.92, however the rear is higher in the 7at at 3.35 vs that of the 6mt 3.69

so the gears sort of equal out (not perfectly) but enough for there not to be a HUGE difference

The 7at has a first gear of 4.92 (based on two separate sources).... and a rear of 3.35

I think there is a low level of knowledge on here regarding transmissions and gear ratios... (this is not directed at Ivoidwarrenties, I believe you know what you are talking about based on what I have seen in your posts) Everyone else is mixing up gears in the trans with the rear end

 

I must have got lost, I thought we were talking about the rearend here. I didn't know the conversation went the way of the transmissions.

This is what I've gathered so far as of rear gears:
5 sp auto - 3.692
7 sp auto - 3.357
6 sp manual - 3.692
convertable - 3.92x
I want to put 4.08s in Her G37. I just need to find a set that fits.

 

Those numbers are all correct (I assume, based on other sources)... however, some people don't know that the term "swapping gears" refers to the REAR GEARS...

So amongst the talk of all the possible rear end ratios, some people looked my chart and saw a whole lot more numbers to choose from (I have the internal trans gears listed as well) So they started pulling numbers from there, adding confusion to the whole situation

 

Do you know if the carrier housings are all the same or no? The guys with 370Zs say that in order for a 370Z with an automatic to go to 4.08s, they first have to switch to an axle from a manual 370Z. I don't know why this is or if this is true for the G37s as well.

 

Ok your correct. I was misunderstood with his post. When he just said 4.92 I was assuming he was talking rear gears. I have no idea why he was mentioning the 1st gear. Also, I knew one of the cars had the 3.92, it's just the vert and not 7spd coupe.

 

Yeah, Ill just stay away from this thread for a while

 

I couldn't tell you...

I am real curious to see the results of this as far as how the car feels, and how much a difference in MPG should be expected (I am pretty content with the 20.5 mpg @ 32 mph average speed as calculated by the comp over the past 3,000 miles)

and does anyone know how the speedometer is going to be reprogrammed?

 

I've read (but haven't confirmed) that the speed is taken off the half shafts. If that is the case, no need to reprogram the speedometer.

The thing about gas mileage and gears is, it all depends on your driving habits. If you do a lot of driving in town or stop and go traffic, chances are you could see an increase in gas mileage.

I'm willing to bet that the G would feel great with a little more leverage off the line.

 

The 370z guys never said anything about there speedos being off so I think it should get it from the same place on the G.

 

I used to have a 350Z that I swapped 3.93 gears into, the speedo was only off by 1mph but I also had 19 inch Volks so I can assume the computer compensating for the shafts is true.

Going from the 350Z's 3.5 rear gear to 3.93 rear gear was huge, my gas mileage dropped 2 mpg but the 04 Z only had a redline of 6800 so I was still in higher RPM cruising than with the G.

As for the acceleration, the difference will feel extremely noticeable. It turned the Z into a nail driver. The side effect is that if any of you have lightened flywheels like my Z did, they will get old fast as it will rev extremely fast when you are trying to drive slow with the aid of the gears and will make driving tedious for those of you with 6MT's. As well once I had the gears in putting my foot down in 1st gear was near useless, it would just spin the tires if you didn't slip the clutch heavily.

Just thought I'd drop some input from someone who has been there.

 

Thats good to hear as far as the speedo is concerned...
and as far as the mileage goes I wonder how much difference it will be riding down the highway in 6th (I am lucky to have some highway driving to keep a respectable mileage)

Right now @ 75 mph the calculated rpm is 2,750 rpm so I wondering how going from that to a calculated 3,040 rpm with 4.08 will affect it...

I can't see it hurting my MPG that bad