Where did you get the gears?????

Haven't you read the thread? It has the Nissan part#, just do a google search for that number and OEM Nissan parts or go to GTM's site.... jnaut also said he could get them, you could pm him too.

lolol

but for a AT???

Trying to decide which final drive would be best. I have a bone stock 09 370 nismo, that i plan on boosting with the gtm TT kit. This kit alone will give me approx 500whp. However, i want to do gears first. Any thoughts on this Dilemma? Has anyone else did the 4.08 or the 3.90s with an FI setup?

traction is already going to be a big issue for you with a TT setup. I would stick with the stock gearing. I've even seen, perhaps not here but def with boosted 350z's, going to the A/T gears in a manual so they can stay in gear longer.

IMO, if you drag race, 4.08s are great if you stay N/A. Go FI and I think stock gearing is the best bet. As far as road courses go, it seems to be a 50/50 split on whether or not more aggressive gears are good.

I've had my 4.08 gears for just over a week and would never go back! I shorten the gearing of almost everything I have. IMO, makes the car feel much quicker. Second and third really pull nicely:-)

Will be going to Michelin PP shortly, and I'm expecting them to hook up better than the OEM crap that on there now. Car is sneaking up on 10k miles now and the rears are wasted...

Do you think a stickier tire compound would limit or remove all if not most of the traction issue along with OS Giken LSD when turbocharged?

/\ both of those things will help alot obviously but you are going to run out of gear so quickly with the 4.08s vs stock if you're TT. I know there's a more scientific way to say that so hopefully someone else will jump in here and elaborate on the point I'm trying to make.

Is anyone here using 3.9 or 4.08 FD in a 7AT?

im looking at changing my gears to 4.08 what are the exact parts i would need to buy i have a 7at

Contact Z1 as stated in the first post of this thread. If you do not buy their kit maybe you can at least get a parts list.

ok thanks for the info

No problem, if you go for it keep updates in this thread. I may still do this to our 7AT one day.

Hi,

I drive a 7AT but the kit listed in Z1 states that their 4:08 final drive is only for manual transmission. Can someone kindly point me to the right kit please?

Thanks in advance!

Best Regards,
Alvin

the best bet is to buy a manual rearend and throw 4.10s in that as if i remember correctly the automatic rear end is different might have just been the diff center itself though. you might be able to do it by buying a manual aftermarket lsd to mount the ring to.

The difference is the actual diff between the manual and Auto. The pumpkin and all parts associated are the same other then the diffs themself. I tested putting my 3.3 gears from an auto onto my original manual diff and it doesn't fit. I'm in the process of swapping 4.08 gears and quaife in BUT i purchased the pumpkin from an auto 350z. Shimming definitely is trickier as the use COMPLETELY different shims from each other. My shop had to order a full shim set to get it to work. Should be ready to be installed next week.

Sub'd

Here's a review I made from my install last week:
Review 4.08 Ring & Pinion Swap, she's alive! - MyG37

i have install 4.08 gears in my 7AT and its brilliant, i would never go back. what i had to do was buy the Z1 kit ( this is a must makes things easier) and then buy a pumpkin of a manual 370z and install it all into that and then swap over the pumpkins. not that hard to do and the difference is absurd.

According to your post, it says an AT pumpkin will not work no matter what. Shop said there is no problem making mine fit, they just need to order the right shims but other then that all is well. When he put my Quaife and 4.08 gears in, there was too much back lash whe he used the original shims.

Hi,

Can you confirm if I can retain the AT differential please? And does anyone know where I can buy a full set of shims online?

Cheers!

You CANNOT retain the AT diff. You can use the AT pumpkin/shell but not the actual diff itself. A set of shims is all custom ordered. There is no set shims that magically work. Every thing with the diff is custom fit. Shims can be ordered from .005" to .060" in increments of .005 at $16/pair from Courtesy Nissan and its not likely that you will use the same size on both sides. YOU have to measure the shims and find out which size your need unless you just order them all and figure out which ones you need.... Not only that you still need to measure the pinion depth for backlash. I learned after about 8 hours of shimming that I should let a shop take care of it as this is my first diff but without all the shims at your disposal much less measuring everything to the thousandths of an inch.... Without the proper tools and measuring equipment, there is just no way to install the 4.08 gears and diff properly.

Alright. Thanks a lot for your explanation. Appreciate it!

Very well said.

The ring and pinion sat in the AT housing of a 370/350. The only problem was that we couldn't get the gears to mesh properly and it seemed like it required a ton of fiddling & shimming.

I now understand since the shop contacted me yesterday morning. They are actually having to get custom shims cut to make it work. Labor wise, they are charging me a flat rate. The shims custom made are gonna cost me an extra $75.

yeah when i did my quafe in a manual shell i need to grind a custom shim for one side. you have to juggle 4 things when you do it. preload on the carrier bearings, preload on the pinion bearings, back lash, and the contact pattern. it's a bear.

What happens when there is too much backlash?

You will have a sloppy install & your gears will wear out faster. Backlash is the amount of play or slop between the pinion & ring gear. You need some, but too much is a bad thing. It will also affect the pattern.

Thanks for explaining

Not too mention will make it whine like CRAZY! I had the Momentum headers, Z1 test pipes, and Litespeed exhaust and the whine would actually drown out my exhaust when the backlash was set too far off. It would only whine on decel though.

The gears are awesome. Got Quaife + 4.08 FD nissan gears. The car moves really well.

I can add a few engine mods to add a bit more power. Better wheels+tires and a lighter flywheel will also help.

The Z can be made really awesome...

4.363 FD + OSG Super L0ck + SPL traction bars & AL diff bushings + YokoHama AD08R = :rock:

Vids??^^

I've come full circle now. At about 32k miles I swapped to 4.08 gears. Then just about a month ago at 76k miles, I swapped back to the factory 3.69 gears. For the record I've got a 6MT.

I miss having the 4.08's driving around town. Ripping through 1st, 2nd, and 3rd gear was so fun.

Highway driving is more fun now with the 3.69's. Rolling at 70 then drop it into 3rd and just let it go. Shift to 4th then hold it until .....

Going from 4.08's back to 3.69's makes the car 'feel' slower because it's not revving as quickly.

Why did I swap back to stock gears? Got tired of the gear whine.

Is the gear whine because of the brand of gears you used, or 4.08 gears in general? If theres one thing that peevs me its gear whine :shakeshead:

I don't have any gear whine. If there is any, it is about 90% less than before the swap. I had a base open diff (peg leg) now with Quaife + 4.08s and redline fluid the noise is almost gone (girlfriend verified). I can actually hear the engine AND the F.I. exhaust now.

I'd say over 90% of the time, gear whine is due to bad install. Setting up gears (ring and pinion) ain't to be taken lightly and is a very time consuming process. The 4.08 gears Trance is referring to I assume are the Nissan OEM gears from a Frontier, so they should be good quality, but made in cHina of coarse. Perhaps Trance can elaborate on who installed the final drive. Was it just some tek in a performance shop or an experienced trans/rear end shop that specializes in built trannys/rear ends?

Here's what to expect based solely on the math. This is a comparison I did for my own Z, which is a 2013 Nismo with Nismo wheels & stock tires (285/35R19). This should give you an idea of what to expect. It will be different for the 7AT.

http://www.the370z.com/attachment.ph...1&d=1409169965

Hey guys,

I want to go 4.08 on final gear, got ATS 1,5 way Carbon LSD on 7 AT
Those who did it on 7 AT, could you please advise will MT 4.08 final gear fit ? If not what I have to order (swap)
Thank you