I read that whole sticky and used the search function and cant find an answer. I just wanted to know if 3.7 FD would be the best choice for a 5AT 3.3 FD. If yes all I need is the 3.7 FD and new bearings for the pinion correct?, thanks

 

If you want to swap FD's you will also need a 6MT diff also.

The 3.7 FD is an excellent mod for the 5AT. I'm personally going with the 3.9 FD at the end of the month when it gets here .

 

Yes, I feel the 3.7 would be the ideal gearing, I have the 3.5 now and am upgrading to the 3.7 as I feel the 3.9 might be a little much for me.
As stated above you need to swap rears with a 6mt car first or get the LSD from one as the auto gear is physically thicker and has a different LSD.

 

Im not planning on doing a swap with a 6MT, Im just buying the 3.7 final drive separately. Will I still need to swap rears with a manual for this to work? ,im getting confused. Rears is referring to pumpkins correct?

 

There are several things to consider when swapping out rear end gears/parts.

Vader007 is correct, the actual gears on a 3.33 automatic are thicker than the 3.53 and lower gears. The flange on a 3.33 differential is moved over a bit to accommodate these gears. That's why the 3.70 gears won't fit a housing from a automatic (3.33). Someone might sell a spacer to adapt the lower gears to your automatic diff, but I would avoid that.

You might want to buy a new LSD with better clutches. Changing gear ratios is an opportune time to change the diff too, and it will solve your gear thickness problem. There are also some stub-axle issues if you don't already have LSD.

Talk to the person you're going to have install the gears for you. They should be familiar with the situation. I bought my gears and Carbonetics diff from Adam at Z1 Performance. He's a sponsor here and good guy, give him a call if you are interested.

 

It is my understanding that the G37 5AT already comes with the 3.7 FD and LSD. Just buy the whole pumpkin from Infiniti which is what I am planning on doing in the spring.

 

The G37 6MT does come with a 3.7 FD. That would seem to be an awful expensive way to go... might get some better performance from 3rd party diffs, too...

Good thinking, though... It pays to look at all the options before you buy something this expensive.