Hello everyone, I have a 2012 G37xs Sedan. I was thinking about putting a higher ratio differential in. I believe I have a vlsd diff in it now? Sometimes I can get both wheels to spin, but most the time it's a one wheel peeler...lol As far as getting the diff welded, can I just take my diff into a shop and have them weld it up? How much would that usually cost? Also I believe I have 3.3 final drive in the car now. Im just looking for a little more acceleration. What ratio would you guys recommend going with? Also I've seen traction concepts diff rebuild kit. Would this be a better option than a welded diff? Im just learning about everything now, so plz forgive me if I sound dumb.Im just looking for a cheaper option to have 2 wheel peel, and a slightly higher gear ratio. I cant find any video online of a comparison in performance between diff gearing on the G37's. Any feedback is greatly appreciated.

 

I have looked into doing the same several times with a RWD VLSD sedan, and the gear change process isn't straight forward. Some also report issues with cruise control after performing the mod.

At a high level, in order of ease:
-6MT, buy new gears and install them

-RWD 7AT, source a pumpkin from Sport Model RWD transition year and make some light modifications to the drive shaft, buy new gears and install them
-Z1 also offers a product, but I know little about it: https://www.z1motorsports.com/differ...l-p-62686.html

Update, spoke to Z1: "Hey Mike - thank you for reaching out - per my diff builder; "His Only option is to get an auto from a 07-08 G35 sedan or auto 08 G37 coupe diff. Those are the only ones that came with a 3.69 from that factory and will fit with his 3 bolt companion flanges. Other than that, no options." I hope this was helpful. Z1, Cam"

-AWD, comes with open diffs front and rear but uses a viscous coupling that helps send power to the wheels, it's my understanding on AWD that changing the gear ratio is not possible due to the DSP/ECU controlling the AWD mechanism.
-Seems that someone has done this, so I may be wrong: https://www.reddit.com/r/G37/comment...ion_gear_swap/

I've read that welding the diff causes drivability issues, so I haven't spent much time looking into this option. I know that Q owners like traction Concepts LSD Conversion kit as even the Red Sports leverage an open diff: https://www.tractionconcepts.com/Inf.../tcxin4920.htm

 

Ok Thank you! Interesting, I would like to know why the cruise control could fail with different gearing? o.0 I didn't mention, but my awd system currently is only rwd.(Can comm error) I did wonder though...if you change the rear diff gearing in a working awd setup, do you have to change the front diff to match? I think for now I will try out the Traction concepts diff upgrade. I rly dont want to create new problems.

 

I believe the output speed sensor mismatch is what causes cruise control not to work. I am really out of my depth speaking in detail about how to modify an AWD diff.

This is what I believe RWD G owners are looking for: https://www.ebay.com/itm/167329688845

3.692 gear ratio is better, but it still appears to be a VLSD, which ages over time and the vicious fluid degrades.

A 6MT diff works (with different nuances), but good luck finding one of these in a salvage yard.

Try to find that user referenced in the Reddit post that upgraded their AWD diffs.

 

Good info, socket.

And you're right about the 6MT being the most straightforward gear mod (for my mechanic, LOL) Short gears in an AWD car, not so much.

The 3.69:1 gears were used in the 2008 5AT Coupe, and every year 6MT throughout the G37 model. Except the 6MT Vert, which had a 3.9 rear end, but no limited slip. That was an oddball.

Anyway, short diff gears are a fantastic mod. So much torque down low, it's a rush.

 

I'm jealous of you 6MT guys. Something about spending a thousand dollars in parts and labor to put an old VLSD G35 diff in the car hoping the salvage yard correctly identified lets the winds out of the sails for me. Wish there were more 6MT diffs available, but 6MTs are hard to find as most would do a salvage title before letting one go to the scrapyard.

 

I have a 6MT, so I can't speak to the AWD or auto transmissions themselves.

What I will mention is that on my 2004 G35 6MT Sedan I burned out the VLSD unit in about 30k miles of ... very spirited driving on the street and some driving on the track. I replaced it with a Quaife helical limited slip diff and loved it. When I upgraded to my 2009 G37 Sedan 6MT a few years ago, I (1) supercharged it and (2) immediately put in a WaveTrac helical limited slip diff. The two are comparable and both, since they are mechanically geared diffs, have no wear and never need replacement and only the occasional fluid change. If you don't love your current diff, rather than messing about with different gears perhaps look into what it'd take to put a better diff in place of the stock VLSD. In my G37 it was a halfshaft, the diff itself, and I had a professional shop put it in and shim it. Done and done.

Good luck!


Rick

 

On the Auto RWD, the R200 pumpkin needs to be changed. I am however confused as to why, but that confusion likely stems from my understanding of how an old school posi-traction diffs work.

For now, it appears that love the one you are with is the path for AWD/RWD 7AT owners (majority of the Gs sold).

I almost wonder if a R190 open diff swap from a Q50 with a Traction Concepts LSD kit is a better fit as I can find very low mileage R190 diffs for sale online: https://www.tractionconcepts.com/Inf.../tcxin0924.htm

First world problems.

 

It looks like Wavetrac supports the R190 diff as well:

https://www.wavetrac.net/collections/infiniti

Quaife may support all AT models?

https://conceptzperformance.com/quai...10l_p_7025.php

 

Good find if any of you RWD folks are in TX: https://www.ebay.com/itm/306433529701