So if one wanted to upgrade to 3.7 gears, can we use the existing 3.5 pumpkin and have the gears swapped in?

 

You could but it's a labor intensive job, so swapping pumpkins is a cheaper alternative.

 

so im confused now after what someone posted a couple posts up...06-07 Gcoupes have the 3.5FD if you got the sport package?

 

6MT yes, 5AT (mine did)

 

http://infinitihelp.com/models/index.php

will tell you everything you need to know, just hit your model/year then specifications...if you have a manual then yes 3.5

 

06-07 Sports also have the 3.5, I can testify to that

Does anyone want my 3.5? If I find a 3.7 this weekend im going to swap and wont need the 3.5 anymore

 

I went to the thread in the FAQ/DIY section on this forum that has a link for all the Factory Service Manuals https://g35driver.com/forums/faq-diy...e-manuals.html

If you look for the "rfd.pdf" file (rear final drive) and go to the Service Data and Specifications page of that file, it shows you what rear end ratio's were in what cars that year.

See attached files for some of those. The limit is 5 attachments so I just showed these, but you can look up others as you wish.

For example: 06 Sedan (what I have) says that both the RWD and AWD models all have the 3.5. (based on the RPM I'm pulling at 80 mph, that makes sense with mine)

The 05 Sedan shows that the AWD was 3.5 and the RWD had either a 3.3 or 3.5. If you have an AT it is 3.3. If you have AT with sport, you get 3.3 w/ LSD. If you have MT, it gets a 3.5 LSD.

The 04 Sedan shows 3.3 for RWD AT and 3.5 for RWD MT. There is no listing for LSD or AWD. (Did the 2004 Sedan not have these? I'm not that familiar with the 04.)

The 06 Coupe matches the 06 Sedan specs. The 05 Coupe matches the 05 Sedan specs. (At least for RWD since there are now AWD coupes.)

The 04 Coupe (didn't upload that one, but you can take a look for yourself) is a little odd. The MT is a 46 tooth drive gear with 13 teeth on the pinion making a ratio of 3.538. The AT says it is a 47 tooth drive and 13 pinion for a ratio of 3.357. Strange they'd make the one tooth difference.

 

By the way, the 06 Sedan FSM doesn't agree with Infinitihelp's page.

 

I always thought that the Infinitihelp page was wrong. My gf has an 06 350Z, 5AT, and it DEFINITELY has 3.5 gears. No doubt about it. 3200 rpm at 80mph.

 

Good find.

 

So I have an 05 5AT w/ sport package (bought with 7 miles on the clock), and I'm fairly positive I have the 3.3 gears with VLSD.

I'm still trying to decide between 3.5 and 3.7 gears (if I can ever find them). How much worse is the 3.7 on gas mileage? I think that's pretty much the deciding factor for me between the 3.5 and 3.7 gears. I'd love the extra acceleration from the 3.7, but the car is a daily driver and the G is already known for non-stellar gas mileage.

Also, if I do decide on the 3.7 gears, will the Nismo finned differential cover fit on a G37 diff with 3.7 gears (I assume this is where I'll be getting the gears from).

Also, not as important right now, but similarly if I get a diff from a G37 with 3.7 gears, will I have to get G37 specific LSD?

Thanks, guys, this is a very informative (and mod-stimulating) thread.

 

you can swap the whole pumpkin, not sure if the cover will fit as im not familiar with that

 

I could be wrong but I don't think you can fit 3.7 gears in the 3.5 pumpkin. Can anybody elaborate on this?

Gas mileage should only be effected at highway speeds since the engine will cruise about 200 more RPM at the same speed. I doubt you'll notice a difference driving around town.

 

If you're at 3500rpms at 80mph with 245/40R19s, then you don't have 3.5 gears. That rpm is way to high. It may even be too high for 3.7 gears. Are you at a steady cruise, flat surface, and with very minimal throttle when testing this? The rpms at 80 with 3.5 gears should be around 3200rpms or so with OEM size 26.3-26.8" tires.

This whole gearing thing is confusing with these later 1st gen coupes and sedans. My friend's 07 coupe definitely doesn't have 3.5s.

 

is there anywhere you can actually by a 3.54 rear pumpkin?