Whats up members, i am a little confused here. I can see through my research any g37 coupe from year 2008 should be a 3.7 final drive gear ratio. BUT i have also seen someone stating they opened a diff off of an 08 g37 and it was a 3.3 final drive ratio. If i go after a pumpkin that is from a 2008 g37 sport coupe AUTO, am i guaranteed it will be a 3.7 FD eith VLSD? I need some further information here. Thanks guys.

 

I believe the auto had the 3.3, you should be looking for one off of a manual.

 

Hmmm, it is weird because on the technical specs it shows both 5at and 6mt have the 3.7 final drive.

 

I saw that too. I got mine off of a G37s sedan and it was a 3.7.

 

What were the 2 letters written on it? And it was from 2008 auto sedan g37s?

 

I don't have the diff anymore and it was a manual.

 

The tech specs in the FSM are a little weird I think, at worst they may not be totally accurate.

For 2007 & 2008 Sedans, and 2008 Coupes the specs for R200V show a 3.7 FD for both Auto & 6MT models.

Then in 2009 both coupes and sedans are showing 3.3FD for Autos and 3.7FD for 6MT.

Not sure if the FSM is just wrong, or if there was a change in mid-2008. 2009 is when the Autos trans changed over from a 5AT to a 7AT. So that might have affected what FD ratio to use.

Basically it sounds like you should find a 6MT pumpkin to be sure. Or go for a 2007, or early 2008.

 

Exactly, thats what i want to clear up. Prob 2008.5 auto might have the 3.3 not the 3.7 FD. But i found a 2008 coupe S 5 A/T and want to be sure i aint getting a 3.3 but smart thing to do is just get a manual one to be guaranteed a 3.7 w/ vlsd

 

Plus if you get the manual one, you won't have to worry about that weird 3 prong input shaft.

 

What about the 2 letters stamped on the diff. Maybe we can clear some things up if we can get a better understanding of what letters mean what. The current diff i am looking at says "KG"

 

I just picked up a 07 g35s sedan at differential. If the FSM is right you can't go wrong with 07-08 G35s at or coupe 6mt. I knew the diff I had was a 3.7 as the driveshaft flange with 3.7 turns, the axle input shafts are 1 full turn... hence 3.7 gears and I saw it coming off a Sport G35. All SPORT g35 3.7 diff listed as standard LSD equipped. Besides that a positive way to ensure lsd is to drop the cover.

BTW= letters on my new diff is "KG" my old 05 3.5 lsd diff has "GD"

g35club.org for a good link.

 

easiest way to break it down: 7AT is 3.3, 5AT and 6MT were 3.7

 

Hey flushed g35 from the 3.5 to the 3.7 fd was it worth it? How much of a difference of rpm changed and how,did your CC work out and MPG as well. I daily drive so i am a little unsure of getting 3.5 or 3.7 FD

 

Its installed with whiteline but I have not yet driven it as its still on jackstand. Still haven't installed my clutch and this coming weekend is drill ( the rain doesn't help too).. sigh. I read its 100-200 rpm difference in rpm over the 3.5. With my stock 3.5 LSD rolling on 19x10.5 with 245/40 tires at 80 mph I'm at 3k rpm. From reading and research the upgrade from 3.5 to 3.7 is minimal. Now going from 3.5 to 3.9 or 4.08 then you will notice the change. But there is no need unless tracking. Going from 3.3 to 3.7 will be significant in your case. If you plan to fi in the near future just stick to the 3.3 or go for the 3.5 if you want. With a shorter final your rpm will be up there and fuel consumption will climb regardless.

The reason I settle with the 3.7 personally is its cheaper.. i got my 3.7 LSD diff for 200.00 and I plan on fi with the future intention of autox or nasa. The course is short and has a lot of apex with a few 1/8 mile sprints.

Also it is very easy to mark locations off the axle flange and driveshaft flange of the differential. Rotate the driveshaft flange 1 full turn and count how many turns the axle flange does in the process. The final turn should settle at a certain o'clock position to determine the final gear drive ratio.

 

Hmm i have 275 35 19 in the back and i am right about 3000 rpm at 80mph cruise. Maybe the 3.7 will be too aggressive for highway commuting. But i might just go for it.