Need help! 5AT to 6MT differential swap???
 

I have a 04 g35 coupe 5AT. I want to switch my gears up for acceleration. Are there gears I can buy and put in or I heard something about swapping the differential for one that come out of a 6MT? If so what gears would be best?

Ive done CAI, 75mm throttle body and spacer, 5/16 plenum spacer, x pedal pro, test pipes Y pipe mufflers, uprev tune.

Auto: 3.3
6MT: 3.55
G37 6MT: 3.69

Your speedo will be off if you change up the final drive (only a problem for auto trans cars), but it's been done.

Speedometer will read correctly if you replace the entire differential though, at least the 3.5 anyways. Different number of wheel speed sensor pickups on the stub shafts.

Never heard of that. Everyone on here with an AT had a wrong speedo after swapping diffs.

Makes no sense to me because I thought the speedo uses the abs sensors in the diff. Apparently the auto cars use the transmission speed for speedo display.

Well then nvm, I thought the rings were different and the speedo read the same.

6MT uses the wheel speed sensors on the differential to determine speed, I guess I ASSUMED the 5AT did as well.

I swapped the 3.3 for the 3.5 and didn't notice much, if any, difference in the speedo. OP be forewarned though that it will shift the RPMs at speed and if you do any highway driving your gas mileage will drop dramatically. After the swap running 80 MPH down the freeway put the motor running at 3200 RPMs on a 5AT. That little V6 was really working hard...

Did u notice any difference in the acceleration?

Yep, it'll jump off the line with a little more gusto. However because it will move your shift points you'll actually run a slower quarter mile time. If you do mostly city driving the swap is totally worth it. Add a Transgo shift kit to the car after and it will make you fall in love with the G more than ever, it's almost better than having a manual.....almost. :D

Is this what ur speaking of? Lol and also I heard if I put the 3.5s in I have to get a different chuck? Do u know which one? Or are u talking about swapping to a 6MT differential?
https://cimg6.ibsrv.net/gimg/g35driv...878ca4d8db.png

The Transgo is a good mod for the valve body. The easiest way to upgrade gears is to just swap the entire pumpkin. As posted earlier, any pumpkin from a manual G35/G37 will bolt up directly. I wouldn't even bother opening up the pumpkin unless you want to install an aftermarket LSD.

Going from 3.3 to 3.5 is noticeable, not sure if going to a 3.7 will effect your cruise control or not. Speedometers on the later models were definitely effected when changing gears (06 5AT), some have claimed that there is no change on the 1st gens.

Did you do the differential swap and transgo kit?
 

Did you do the differential swap and transgo kit?
wanna know how the results were i plan on doing this.

transgo is well worth the money for the increased shift speed. The other part is for increased acceleration through the gears. What do you want more?

i did a swap from 3.3 to 3.7. all G35/G37 5 speed auto are 3.7 too for 07 and 08 only.
cruise control work for me, nothing odd happen on my car