i want to get a 3.9 final drive. the problem is i have the 5 speed a/t. will the diff from the same year m/t car fit onto my car? or is there more work that i have to do?

 

http://lmgtfy.com/?q=how+to+get+a+3....automatic+350z

 

i read that one before but it never really answers my question. like are the output shafts the same lengths? what other parts would i need? or a tune.

 

you would prob need a half shaft, no tune needed, but can you do the work yourself?

 

yeah i could do all the work myself, i just didn't want to run into problems with parts and not be able to drive my car, or have to put it all back together and do it again when i get all the right parts

 

call concept z... talk to them, they will tell you what you need

 

thanks, i'll try that

 

I see by your question you already know you'll need a M/T differential carrier to install 3.9 ring and pinion.

Easiest thing for you is to buy a complete M/T VLSD rear end w/stub axles and swap your 3.9 ring gear in that one. Then just swap rear ends and you'll always have your OEM pumpkin for when you get tired of the whine (lol, jk). Now would be the best time to get an aftermarket LSD.

To install you will need the master differential bearing/seal kit which has the carrier bearings, pinion inner and outer bearings, pinion crush sleeve, pinion oil seal, side oil seals, and new pinion nut (never reuse your old pinion nut). You will need an assortment of adapters and a shop press to remove and press on new races and bearings. It is definitely doable but you will need to spend some money tooling up and be prepared to have to re-shim the pinion and carrier when setting up the new gears (which involves making some dummy bearings for test fitting). What I can tell you is that most shops just bolt everything together using the existing shims, then run a test pattern and if its decent let it ride.

An involved process for sure (to do correctly).

 

Find a complete VLSD from a manual 370Z. Comes with a 3.69 final drive which will really wake your auto. I did it to mine. Made a huge difference. Only thing you will have to do is swap pinion flanges and your good to go.

 

What remo said, easiest way.

 

+2 with remo!

 

Great suggestion, will save the OP a heap of work.

 

money