So many conflicting answers here is it the 3.337 or 3.538 Final Drive in the 06 coupe? FSM says one thing and the owners manual says something else. What is correct? Is there a accurate chart out there? Looking to upgrade my open dif 06 coupe with a VLSD and I would prefer to just swap the whole pumpkin with something that has a 4 bolt flange. Been looking at g37 4 bolt flange diffs, this is more confusing that I would like. Please help.

 

Retyping this from one of LoSt180's posts.

V35 AT 3.3 FD
V35 MT 3.5 FD
V36 5AT 3.69 FD
V36 7AT 3.3 FD
V36 MT 3.69 FD

I believe all MT's came VLSD, not sure about the AT options.

The 370Z and G37 had a couple of flange options on the diff (basically the AT was different bu MT should he the same) but they can be swapped around, you would have to Google it.

 

Best thing would be to just ditch the VLSD and go to a clutch style diff though, there are some very quiet options from ATS but they are spendy.

 

I agree the VLSD is not the best. However I don't want to get overboard here as I tend to do sooo very easily. I'm looking to just spend a few hundo and change out the whole pumpkin. So from your post above it seems the FSM was incorrect by saying the 06 FD is a 3.5.

 

The 2006 is 3.538 which I believe is exactly what it says in the FSM, not 100% sure at the moment I'm on my phone and getting an error on the Nicoclub website when trying to access the FSM ?

 

So it is true, 5AT 2006 coupe is 3.5. This is what makes it so hard, don't want to go to a taller FD if I already have the 3.5FD.

 

I believe that is incorrect, the 5AT 2003-2007 coupes came with the 3.3. It's my understanding only the 6MT VQ35DE's (sedan/coupe) came with the 3.5.

 

Maybe? The FSM does clearly state the exact same FD gear ratio for both transmissions for 2006 which I thought was odd. I can't check the other years because something is wonky with the online FSM's on nicoclub and it says I don't have permission.
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Wouldn't a good way to tell would be to take said 3.5 5AT 06 and take the RPM at 60mph vs a car with a known 3.3? I'm willing to test this out if someone with a 3.3 car would like to help.

 

The dif does not seem to have markings or a label with the gear ratio like my caddy has on the diff.

 

Make a mark on top of the axle output shafts and the propeller input shaft (just make them all straight up for simplicity), turn the input shaft and count the revolutions until the axle shaft mark is straight up again. The input shaft will either be slightly BEFORE or almost exactly 180° from the original position depending on if it takes 3.3 or 3.5 revolutions to turn the axle shaft.

Make sure to turn the axle shaft by hand and verify the opposite axle turns the same direction to ensure you do indeed have a VLSD. Next hold one axle shaft and try to turn the other one independently, there will be very stiff resistance but they will turn independent. Was just showing a neighbor how to tell which is which last weekend when doing a diff bushing.

Edit: if they turn the same direction but there is not much resistance turning them opposite of one another the VLSD clutch pack is shot.

 

That could work too, I guess my theory would be grossly inaccurate do to tyre size, etc. There is no markings on the dif itself that says the gear ratio?

 

There's some factory stampings on it but I have never looked up what they mean, I usually just turn them by hand to verify what it actually is but that's just an old habit because you never know what you're ACTUALLY getting just by looking at it Obviously that wouldn't work for one you buy on the internet though.

 

ALRIGHT! Found something super useful over at Z1's website. They have an OFFICIAL chart with all the possible FD gear ratios. Yes the 2006 G's ALL came with the exact same ratio regardless of coupe/sedan/AT/6MT

https://www.z1motorsports.com/upload...GearRatios.pdf

 

2006 5AT came with a 3.5. At least the ones with the sports package did.
You can go to a 3.7. The difference is small but still noticeable. There is also some misinformation on this forum if you search through older threads. Changing the FD on your car will affect the accuracy of your speedometer also, something that didn't happen with the earlier models.