smitty37g

Ok, So I have a question. Is there a way besides taking the rear cover off and counting the ring and pinion gears, to find out war the ratio is??

I ask, because I hear the "S" is supposed to have 3.692 ratio... but according to the spec sheet it says 3.357... Or does any one know which one if correct??

09 37gS sedan, no Tec package, but everything else.. lol

Thanks

zer099

iTrader: (2)

Its 3.357. You can look at your VIN plate on the door just to check for yourself. Under "axle" is your final type: RC33, which is open diff 3.3 ratio.

smitty37g

Well i know its not open diff.. but i will check.. its the sports model.

SonicVQ

For RWD, if you have an automatic transmission, the final drive is 3.357:1 and can be open or limited slip. 6 speed manuals are 3.692:1 with limited slip.

AWD diffs are all open.

zer099

iTrader: (2)

My bad, I think LSD are have the "RA" designation; you are correct in your sport should be a LSD. Either way it is a 3.357 if it's an auto. The only exception, that I know of, is if your driving a 2015 or 2016 NISMO 370z. They have 3.692s in their rear mated to an auto. Your VIN sticker will reveal all however.

smitty37g

Ok. Went out and checked.. it is the 3.35
Thanks for the help... now to look for a 3.69.. lol..

serega13

iTrader: (2)

If you are going to go through all the trouble of replacing your diff, might as well get 3.9 or 4.08 final drive.

smitty37g

Well i still want to have decent gas mileage.. but thats in the near future..

zer099

iTrader: (2)

4.08 and 3.9 are very short with the auto gearbox. I imagine there would be heavy traction issues in first and second depending on your power. That said most might not care about that, others may. It really depends on your goals.

Here are some numbers to look at with the 7 speed auto gearbox and diffrent finals:

275/35R19 tires (26.58") w/4.08 Final
1st: 4.923 MPH @ 7500 = 30; Shift point: -
2nd: 3.193 MPH @ 7500 = 46; Shift point: 4940
3rd: 2.042 MPH @ 7500 = 71; Shift point: 4845
4th: 1.411 MPH @ 7500 = 103; Shift point: 5167
5th: 1.000 MPH @ 7500 = 145; Shift point: 5312
6th: 0.862 MPH @ 7500 = 169; Shift point: 6446
7th: 0.771 MPH @ 7500 = 189; Shift point: 6720

275/35R19 tires (26.58") w/3.9 Final
1st: 4.923 MPH @ 7500 = 31; Shift point: -
2nd: 3.193 MPH @ 7500 = 48; Shift point: 4880
3rd: 2.042 MPH @ 7500 = 86; Shift point: 4832
4th: 1.411 MPH @ 7500 = 109; Shift point: 5217
5th: 1.000 MPH @ 7500 = 152; Shift point: 5324
6th: 0.862 MPH @ 7500 = 176; Shift point: 6460
7th: 0.771 MPH @ 7500 = 197; Shift point: 6690

275/35R19 tires (26.58") w/3.692 Final
1st: 4.923 MPH @ 7500 = 33; Shift point: -
2nd: 3.193 MPH @ 7500 = 50; Shift point: 4918
3rd: 2.042 MPH @ 7500 = 79; Shift point: 4765
4th: 1.411 MPH @ 7500 = 114; Shift point: 5202
5th: 1.000 MPH @ 7500 = 161; Shift point: 5320
6th: 0.862 MPH @ 7500 = 186; Shift point: 6477
7th: 0.771 MPH @ 7500 = 208; Shift point: 6693

275/35R19 tires (26.58") w/3.357 Final
1st: 4.923 MPH @ 7500 = 36; Shift point: -
2nd: 3.193 MPH @ 7500 = 55; Shift point: 4878
3rd: 2.042 MPH @ 7500 = 87; Shift point: 4766
4th: 1.411 MPH @ 7500 = 125; Shift point: 5209
5th: 1.000 MPH @ 7500 = 177; Shift point: 5305
6th: 0.862 MPH @ 7500 = 205; Shift point: 6475
7th: 0.771 MPH @ 7500 = 229; Shift point: 6707


My biggest issue with the 4.08 and our auto box is you will most definitely be changing to 5th in a quarter mile pull which will eat at your time. All that said I could be wrong about traction and time loss due to added shifts in the quarter.

Note: for those that do not know the shift point is the RPMs the engine will drop too when shifting at the set number for the previous gear. For these examples it means shifting at 7500, the typical shift point I presume for the majority of the forum users on here that might push their car. This number is presented so you can know where in your power-band you will be dropped to after the gear change.

Disconnected AW

Guys I been searching for a while. What the heck is the final drive ratio of the awd diff? the only answer is here and you said. "Awd is all open diff" i don't know anything about diffs but I want lsd.

My only other option is to get another rear diff stock and weld it to have it installed and Uninstalled intermittently to have fun once in a while in the summer then go back to stock open diff... is it possible to install lsd on awd model??

G37xFreebird

I could be wrong but i was told by REDDIT (this is why i may be wrong) that the awd has a ratio of 3.357 ill link the post where i found this as i was researching too looking for the same answer as you. https://www.reddit.com/r/infiniti/co...l_drive_ratio/

ILM-NC G37S

iTrader: (3)

From the 2010 Coupe- all "X" models are the same:

zer099

iTrader: (2)

Your stock AWD diff ratio is 3.357. If you want to change it you need to also match the front diff to the change.

Yes, you can upgrade you open diff to a LSD. It's the exact same as all the other auto rear diffs. Just follow the instructions for do so and keep in mind you u-joint yoke is different. Also pay attention to what mounting style you have on the diff output shafts, there are two different styles.

Yes, you can also upgrade your front diff to a LSD as well. It's the exact same front diff casing as the R35, and the internals are swappable. That said, you will be paying GTR prices for something where that money might be more wisely spent elsewhere.