Nissan 370Z Forum - 4.08 Frontier gear swap

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- - 4.08 Frontier gear swap (http://www.the370z.com/engine-drivetrain/18209-4-08-frontier-gear-swap.html)

sorry noob question but why would it be bad to change to 4.08 if i plan on boosting my Z?

I have a 7at G37 and have the 4.08 installed. My 1st is 30 mph 2nd 45 3rd 60.

having to shift to 3rd to get to 60 seems a bit excessive. Should i drop to 3.69 or 3.9?

Quote:

Originally Posted by kosstick (Post 1097706)

I have a 7at G37 and have the 4.08 installed. My 1st is 30 mph 2nd 45 3rd 60.

having to shift to 3rd to get to 60 seems a bit excessive. Should i drop to 3.69 or 3.9?

Correct me if im wrong but i read in some other threads that the AT Zs has a smaller last gear so if that is true the4.08 is big for the AT because the trans. already has a higher ratio so now it is too high i guess

i have a MT I think AT guys will give you more info.

Quote:

Originally Posted by Nissanboy (Post 953454)

sorry noob question but why would it be bad to change to 4.08 if i plan on boosting my Z?

i would like to know the answer to this as well

Quote:

Originally Posted by Osiris (Post 1137469)

i would like to know the answer to this as well

it's just a recommendation due to traction issues. with 4.08's and boost you will have a harder time keeping the rear end in a straight line and you will run out of gear quickly with all the extra power.

Quote:

Originally Posted by Nissanboy (Post 953454)

sorry noob question but why would it be bad to change to 4.08 if i plan on boosting my Z?

Quote:

Originally Posted by Osiris (Post 1137469)

i would like to know the answer to this as well

I've driven an all motor Z with 4.08's. you don't want to run boost with those gears.

so at normal speeds what are your rpm's and does this effect the temps any on regular driving or is your car oil cooled?. im from texas so i dont know if the shitty weather has something to do with it, but if ur at a high rpm for a "long" time the temps can start to change quite a bit.

Quote:

Originally Posted by jnaut (Post 530450)

the diff housing are the same between, the difference is inside , the carrier ( where the ring gear bolts up). you would need to change that carrier plus the stub shaft and axle if yourgoing to run lsd or get a manual rear end out of a 350,g35,g37,370z. then do the gear swap. now if you dont want to go as agressive you can put in the stock gears out of a manual 370z, as the auto 370z has 3.3 axle ratio and the manual has 3.6.in the f.s. section there a stock lsd with gears. he prolly has everything you need to do 3.6 ratio swap for minimal money.

1. Both lsd and non-lsd manual 370z take the same gears. no mod needed to do the 4.08 ratio swap. straight install.

get parts from 2006 nissan frontier xe 2.5l manual trans

1. 38100-0c760 ring/pinion
2. 38165-0c020 pinion crush sleeve
3. 43262-01p1a pinion nut
4. 38154-0c000 spacer between pinion bearing and drive gear
5. 38120-ec000 pinion bearing
6.gasket maker
7.gear oil

optional parts( i did not use these but the installer might request that you repalce them)
8. 38140-0c000 pinion bearing
9. input shaft seal

Great thread man, thanks for all the info ...

I'm doing this in my G - where's the place to order these?

Yes I do 4.08 and 500 rwhp with drag radial at 15 lbs = 11.3? 1/4 mile times
and a fully glued lane. Shifting at 7800 rpm/ God bless the 7 AT.

So what's an estimated total cost to do this for a 7AT?

Quote:

Originally Posted by Z eliminator (Post 1293318)

Yes I do 4.08 and 500 rwhp with drag radial at 15 lbs = 11.3? 1/4 mile times
and a fully glued lane. Shifting at 7800 rpm/ God bless the 7 AT.

if you already have traction problems with 300+ rwhp what makes you think it will stick with 500rwhp?

Just a heads up to those with SRM wanting to do the gears: If you have an upgraded clutch, the 300rpm difference is EXTREMELY noticeable both on up and down shift. In order to get smooth shifts you need to slip the clutch slightly as opposed to just letting off immediately like you could normally, otherwise it makes for an unpleasant ride.

@tranceformer and jnaut -

In the parts list you guys don't list the side carrier bearings/seals - and you list the front shaft seal as optional? Can you get that off and still reuse it? I notice in the FSM it says not to.

Do those side seals/bearings need to be replaced as well? I notice all the retail "install kits" include those. Wondering if maybe with 25,000 miles on my G if I should expect to replace those as well?

Just get the gears from Z1 and order the install kit with it. Comes with everything needed.