I don't have the video I took earlier this week up still but I took another few tonight. Seemed to be getting around 5 - 5.5s tonight and this seems to me to be due to my rear tires chirping when switching into 2nd gear. I think with grippier, wider tires I could easily launch and get 4.5s 0-60's reliably. Also realized I wasn't in DS mode just now but I doubt that would make a big difference besides slightly quicker shifts.

Youtube video here:
I wonder just how much faster this car would rev with a lightweight driveshaft and a tune.

 

What a waste of money !!! Gear swaps do absolutely nothing !!!!!

 

Hahaha your thread is the reason I did gears man, how do you like your 4.08's?

 

Love them ... Now I have a decision ..... I am buying a turbo kit and everyone says I need to take them out . Whats funny is that a lot of people said my 1st gear would be useless once I went to the 4.08 gear . Couldnt be further from the truth . First gear is great in the car now . So I do not know . I think I am going to leave them in and buy some expensive sticky tires and see how I like it .

 

If you want, I have a spare set of 3.6 gears from the manual I am selling :P hahaha I think you'd be fine with some 285 pilot sports in the rear though

 

Thanx for the offer . If traction becomes a issue and I am having trouble building boost I will go back to my stock gear . I have wasted sooooo much money on this car . I have parts that I have purchased and have not installed yet . Blah !

 

^^^ Great vid!

NBS: although the TT will be able to pull longer gears, it's also able to spool up in addition to them. You know this.

NO gearing which will contain first gear on a twin-turbo is going to be as much fun from 2nd-6th. That's the tail wagging the dog. Just limit that right foot for a moment.

To recap:
1. The automatic differential guts need to be replaced by a manual LSD from ANY year 350/370/G35/G37?
2. Then a set of Frontier gears purchased and installed onto that pumpkin.
3. The automatic's pumpkin driveshaft flange needs to be swapped into the manual's pumpkin
4. Install, measure/fit and go.
5. Probable loss of cruise control.

Part numbers for 4.08 Frontier gears? (I even read on a spec chart that a model Frontier also has 4.36:1 diff. Oh, my....)

Coop

 

mine are @ approx 3100 rpm

 

The automatic differential doesn't come into play at all besides swapping the flange. You don't need to open the auto diff at all, there is a small difference on the inside (even though physically from the outside they look identical) that prevents the shorter gears from fitting properly.

When you buy the manual diff from the 350/370z or the g35/g37 (any year will work for those as long as it is the VLSD diff, otherwise the inside will not be big enough) you actually swap the 4.08 gears into the manual diff and put the manual diff on your car. The only thing you do to the auto diff is remove the driveshaft flange and swap it onto the manual diff so you can use your stock auto driveshaft.

Unfortunately, I don't know the 4.08 gear part number but the part number for the 3.916 gears is 38100-0B66A from Nissan. I believe the frontiers have 3.916, 4.08, and 4.36 gears available to use in our cars.

So basically you have:

1. Acquire an entire Manual VLSD Differential w/ housing from any year 350z/370z/g35/g37. In my case the differential came off of a 2010 6mt g37 coupe.

2. The shop will open the manual pumpkin you bought and install the Frontier gears into it. This is where the calibration comes into play, the gears need to be able to activate the VLSD portion (since it's not a clutch-type LSD, it relies on exact speeds and pressures,) and not whine at any speed. There are other parts you need as well like crush collar, shims, gaskets etc but any reputable shop should be able to figure it out. Here is what Sebastian@SpecialtyZ quoted me for parts:

4.08 Gears $535
Seals, bearings, shims, crush collar, etc.. $300
$29 for Redline Gear Oil GL-5

Note that if you go to a different shop your mileage may vary, and as always labor rates end up being different. Mine came out to about $500 in labor.

3. At this point they will remove the auto diff from your car and swap the driveshaft flange from your diff to the manual one that now has the 4.08 gears inside.

4. The manual diff at this point becomes "plug and play" if it is off a G37 or 370z. The G35 and 350z diffs at this step have a threaded hole on the output shafts connecting the diff to the wheels whereas the G37/370z ones have a smooth, non-threaded hole and a small amount of work is needed to get those to line up properly but it isn't hard to do. Also note that if your car was NOT originally equipped with a VLSD diff (i.e., if you have a non-sport G37) you will need 1 different output shaft to make a VLSD diff fit your car. Regardless, any shop will be able to put the diff in the car at this point.

5. Then they would put your car back together and you'd be good to go! If you are auto you lose cruise control pretty much guaranteed, but as a note cars with the 6MT transmission don't have that problem (different cruise control logic, so their cars don't have any issues with cruise control w/ non-stock gearing)

6. The leftover parts you end up having are: Your entire auto differential with the stock gears in it, but with the manual driveshaft flange, and a spare set of the 3.6 gears from the manual differential. You can sell the auto differential and gears to recoup a significant portion of the costs.

 

^^ lot of good info here, thanks ap0c0lypt1c.

do you know if the 5AT flanges matches the 7AT flange?

And instead of swapping the flange from an AT to MT, can you swap the MT driveshaft to AT? maybe get a aluminum or carbon driveshaft at the same time.

 

What's your MPGs now?

 

Mad legit and detailed info ap0c0lypt1c.
Thanks for putting in your time to write up those replies!

 

Reference post #15

Bone stock gearing 6mt sedan

6th gear
60 mph 2200/2300 rpm
70 mph 2500 rpm
80 mph 3000 rpm

 

Great write up. I was the first 2010+ sedan to go to them which is when they figured out you needed a diff swap to get it done...one year later and I'll be going in next month to finally do the 4.08 gears.

 

Usual response style to everyone:

@indyn: The 5AT and 7AT flanges are different. I don't know for sure, but I'm 90% certain you can't swap the Manual driveshaft to the AT unless you were somehow able to change the output flange on the transmission itself to match what the 6MT flange is. The 7AT has an "X" shaped flange on the differential with each point of the X having a bolt hole. The 6MT flange is a circle with 5 evenly spaced bolt holes. Judging from how differently those are designed, I'd wager there is something on the other end that is different too.

@bluedevils95: I'm still on my 2nd "real" tank of gas since this mod. Currently the computer reads that I have the same expected miles left as any other tank I've driven. On the drive home (3 hrs) from Chatsworth, CA, I determined my highway mileage is only slightly worse (0.5 - 1mpg difference.) So far driving around in the city I can safely say the mpg is no worse than before, perhaps even slightly better. I think driving style and highway time will influence how much this mod impacts your gas mileage.

@Jsolo: for everyone else's reference, here are my approximate RPM's at those speeds:

3.916 gearing 7AT Sedan

60mph - ~2500RPM
70mph - ~2800RPM
80mph - ~3200RPM

@jamesshifflett - They actually asked if I knew you haha