4.08 Gear Install (7AT) Review
 

Hey Guys, when I was doing research on getting 4.08s for the 7AT 370Z I noticed there was a lot of people asking questions that were not getting answered. I'm going to give you guys some information I read up on and also my review after getting my gears installed yesterday.

Informational:

-The 7AT will lose cruise control. The light will just flash when you try turning it on.

-The RPM increase is around 600-700. See Videos of before and after posted below.

-Due to the RPM increase, there will be a decrease in highway MPG, but you can possible see an increase in MPG in city driving since it takes less work for the engine to get to the speed limit. Personally, I didn't notice a difference at all.

-For the 7AT you will need the differential from a manual 370Z to install the 4.08s.

-You can use the stock VLSD or an aftermarket one.

-The top speed will decrease from something like 200MPH to 180MPH. Realistically I doubt any of us will ever go that fast.

-Acceleration increases throughout all the gears and you will notice a loss in traction especially in 1st gear. Throw some good tires on there and you should be fine.

-Down Shift Rev Matching seems to be unaffected and seems to be working fine. I will drive it more in sport more within the next couple days and update if I notice anything different.

-The car is much more fun to drive now!!! :driving:

My Review:

I first want to start out by thanking Seb at SpecialtyZ for doing my install. He always does great work and answers all my questions. This is the only place I trust to take my Z. This time he did the gear install and GTM transmission cooler for me. Everything so far is working flawlessly!!!

After driving the car, you will instantly feel the difference. The car feels much faster and torquier. First gear is really short and 2nd and 3rd gear feel like your in a rocket. The fun factor is really where it's all at. The car accelerates so much faster throughout the entire RPM range, that its just a blast to smash the pedal and go.

Parts installed:
1. 4.08 gears
2. Gear install kit (Seals, bearings, shims, crush collar, etc)
3. Redline gear oil
4. Manual differential w/ stock VLSD

Seb swapped out the 3.69s from the manual diff and installed the 4.08s. Then swapped out my entire stock differential with the manual one.

Stock Gears 70MPH


Stock Gears 80MPH


4.08 Gears 70MPH


4.08 Gears 80MPH

That's a solid review, thanks for taking the time to so this!

Thanks the the review and the 7at trany fluid change thread!

Awesome.. I love my 4.08 gears, but I do get a little bit of whine at around 80mph. Cruise control works fine and the synchro rev match is noticeably affected unless down shifting while decelerating at the same time. I have 6MT

great review!

so what does that run you in cost including the diff? $2500 more or less....

yeah i am also interested in the cost of doing this to a auto

It all depends on how cheap you can find a manual 370Z differential. I got lucky and got one for a little under 400 bucks. As far as the rest of the stuff goes, here is the approximate amount they cost.

Gears (4.08s)= $535
Install kit = $300
Fluid = $30
370Z manual diff = best price you can find one for
Labor/install = $500, depends on your local shop.

So you are looking somewhere around 1400 +tax and whatever price you can find a used/new manual 370Z diff.

just want to be certain but it this that i need right, just the diff center

http://www.the370z.com/attachments/e..._2216-copy.jpg

No you need this from a manual 370Z

http://www.slidegood.com/media/catal...7565_1_355.jpg

i have a australian 370z 7AT do you think that matters?, i havent seen or read anyone thats done this in australia yet. and thanks for the info. I also fixed up my picture, uploaded the wrong one

is it possible to install the manual diff with the 3.69 gears on an auto? It would be cheaper and still increase acceleration. Not sure I want to go with 4.08. If it is possible I wonder if it would still disable the cruise control.

While you have the pumpkin off the car and opened up, may want to think about upgrading to a nice LSD. Kill two birds with one stone. So some of you may want to factor that into the price as well.

Not cheap, but really good mod. I had these gears and a Quaife diff installed on my 350z. Still debating whether or not to do it to my 370z.

i a have the 4.08s with the built GTM transmion.
when i had the stock 7 AT with the N/A mods on it the car car just runs increadably better than it does with the 3.3 gears.
It also shifts a lot faster in MM mode.
fuel mailage takes a big hit especail if you put your foot into.
Just wait till you do a 2000 rpm launch with the car and see what the difference is and if you shift at redline it really shifts fast,
i have the vid of the tack and spedo on the drag strip, i can email to a member if they want to edit and post it. Im not good a doing those things
thanks

Z

You drop the diff yourself you can save about $400