all done....tomorrrow ill post all part numbers of everything you will need to do this.as for the srm works perfectly except its off about 2 to 3 hundred rpm but it is very close. cruise control works perfect. no ssues at all. it is deff not to radical of a gear, sooo much better acceleration down low in the rpms where we have no tq.

Wouldn't having the crank pulley and fidanza flywheel contribute to the SRM being a little off?

Either way the gears definitely made a difference, you were pulling about as much as you were last week but this time you had a passenger!

btw, we need to get some walkie talkies!

So still good as a DD? So will this make your 0 to 60 and 1/4 mile times better?

I'm curious to how much the SPL diff bushing kit transfers noise to the interior.

We didn't install them.

i dont think it will be the flywheel or pulley causing the srm to be off , it will be the gears i will be a higher rpm than stock, if were are at the same mph.

as for dd use, i see no problem, as long as you dont cruise at high rate of speed for hours on ends since there is and rpm increase.

and on another note i cant wait for my full exhaust, the car is really coming together a lot better acceleration, tranceformer and i went on an empty hyw,(i had my g.f. in my car)it was noticeably different, it is a good test as his is100% stock.

Cool, right now Im kinda stuck between the gears and lad or SC and maybe LSD. Gotta see the price diff between the two.

The gears are much cheaper than the supercharger but won't give you nearly as big a difference. These are two totally different categories of modification.

Yea its all about the money, I am leaning heavily on the SC side tho, just waiting for a few to get it and see how it does and to find a shop I can trust on the install. Buut if SC is a no go then the gears are my next mod.

So with the AT what is different about the diff that makes me have to get a whole new pumpkin? And is it a auto or manual pumpkin from the 350Z Id have to get?

So parts are as this? new pumpkin, gears, LSD, and some kind of rods?

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

Intersting. I might wait for a SRM fix before I attempt this though.

my srm works

Didn't you say it was off by a few hundred RPM? Or is that fixed now?

yes its off by a few hundred rpm,most of the time i dont even notice.

did you install the aluminum bushings? was there any increase in noise after the install?

nope, didn't install them, just mocking them up to see if they would fit. i'll probably end up installing them on my Z.

If you have an open rean and want put install a stock lsd, you will need a passenger side stub shaft from an lsd car, weather it be auto or stick doent matter. If you are and auto lsd/open you will need a carrier from a manual car, not the entire diff. also the ratio for auto is 3.3 and the manual is 3.6 so if you dont want to go a radical as 4.08 just swap a stock manual rear end/gears.

I am digging up threads from the grave because I can't find the one I am looking for. Any idea how much loss in top speed a manual 370z would have when switching to 4.08's?

without a tune you will lose none, i have gone to an indicated 167mph with my 4.08 gears.

Do you know off hand what kind of RPM increase you saw at highway speeds? say 70-80 mph?

i would like to know this too. also would you say this is the most noticeable mod you have done to the car for the price.

Are you planning on getting some runs in on the dyno? Interested on the numbers the gear change makes. I guess if you didn't dyno before the change you'll have nothing to compare.

I hear if you change the final gear it effects gas mileage, is this true? I think I got this from Z1 website. Correct me if I am wrong please.

Definitely true. If your car is always running at higher RPM to make the same speed then you will use more gas.

The car wont make any more power on a dyno, changing the final drive changes how the car accelerates. A 3.69 (stock final drive ratio) the transmission output turns 3.69 times to turn the wheels 1 full revolution. By using a shorter gear in the final drive, like the 4.08, the transmission must now turn 4.08 times to turn the wheel one full revolution. Basically this allows the engine to accelerate quicker because it requires less effort to turn the wheels, but you won't be going as fast.

For example, if your stock gearing is at 40mph at the top of 1st gear, using a shorter gear would be at say 30mph, but it would get to 30 faster than the taller gear will hit 30mph. I just made those numbers up for the example, but I hope that makes sense.

The net result is quicker acceleration at the cost of some top speed and fuel economy. I believe someone with the 4.08 gears (jnaut maybe) said he was still able to hit 160mph, so the loss in top speed isn't noticeable without forced induction and a death wish.

Cool! Thanks for clearing that up!:tup:

Did you ever use one of those dial tools when installing the ring gear?

apologies for rasing the dead btw.

oh and jason i sent you a pm

got it:tup:

Is SRM still working??

yes... just fine. the only issue at all is after random top end pulls( 130mph or faster) it does shut the srm down. this has only happen about 3 to 4 times. after i restart the cars all is fine then.

If I didnt do so much highway driving this would be a ^no brainer

"normal" highway drive no issues at all.

Eh, I don't think it would be a huge problem, but it gets annoying on long trips.

I had the stock 4.10s in my s, and switched to a 4.44, and eventually down to a 3.90 final drive. I love the pull of an aggressiv fd, but when I am making long highway drives, it's just not worth it.

brace yourselves for epic gas prices again..:ughdance:

My z went down about an average of .7 on gas mileage from what I noticed... I can still get 25+ on the highway if I keep it around 70mph though...

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?

Bump for good info!

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.

i would like to know the answer to this as well