Just got my car back a couple days ago from the install of the 3.9 final drive from 350Evo. Since this is a complex install, and we are by no means experts when it comes to driveline components, I took it to a professional who does this stuff day in and day out.

Before I begin the review, a few comments:

Do yourself a favor before you book your install, and have other parts in hand, or at least know they are at your disposal. There are some items that are not necessarily required, but since we "were in there anyway", I chose to do. I relied on the expertise of my installer to tell me what was essential to be changed and what wasn't. I'll update this tomorrow with part numbers from the exploded diagram to make it easier for everyone to order the stuff

Essentials (in my installers opinion) - crush collar for pinion, spacer for pinion, yoke seal, spacers for differential (for side to side adjustment). I also installed a new pinion nut and new axle seals as well, but left the bearings as is (car is an 04, purchased exactly a year ago, has 23k now).

Be advised that some of the parts needed are not cheap! Example, the spacers needed for the diff itself are $14 a piece...for some measly washers! Nissan offers 14 (IIRC) different thickness spacers for the rear diff - the ones you need will vary depending on how your car was setup from Nissan at the factory. We found on mine I needed the smallest spacer for one side and the biggest for the other. Unfortunately the biggest was on national backorder, so I had to settle for the next size down. This left me with slightly less backlash than the instructions call for (.0010 vs recommended .0080), but my installer assured me it won't be an issue, as there was no free play and the overall mesh pattern was excellent (BJ feel free to chime in here).

Out of the box impressions - these are VERY nicely machined pieces. Easily as nice as the factory units. Fit and finish is excellent.

Install - this is where its essential you get the stuff you need from Nissan. DON"T do what i did and wait till after the car is in the air and the diff apart to order this stuff.....all told, between the parts and the 2 overnight shipping charges, it all set me back nearly an additional $170). You'll save yourself time and aggrevation if you plan ahead. Unfortunately the only unknown is the diff spacers...no real way to know what you need till you are in there. But at least check with your parts supplier to see what sizes are in stock or available, and what are backordered.

Once you have all the needed extras, install is a snap for an experienced person. The rear pumpkin is not difficult to remove at all. What takes the time is getting everything lined up to get a perfect mesh (this is where those spacers come in).

I also chose to install the NISMO finned rear diff cover at the same time. Honestly I have no practical use for this part, as my car has not seen the track to date, but what the hell - its $90, and is pretty to look at when the car is up in the air

Impressions - my installer recommended around 200 miles without launching the car, so I am sticking to that....those miles will be done by saturday. I have done quite a few rolling blasts from 5 mph, 30 mph etc. the car is definitely quicker through the rpm range. You notice it mostly in the lower gears, and mostly when going to speeds up to 80 mph or so. Powering out of the turns now is loads of fun. I have had the Cusco RS LSD installed in my car for several months now and have loved it. Now with the gears, the car really has some "*****" when exiting a turn, whereas before it just had bite....very very happy

Only thing I have noticed is a bit more whine than before. My car started as an enthusiast version. Not sure of the fluid he used in the rear...I'll try to find out tomorrow. perhaps it needs some break in, perhaps it is just how it sounds, or maybe its the slightly increased clearance I am running. It's not annoyingly loud mind you...the type of thing only I would notice. It is only present at light throttle inputs between 2k and 3k.

Overall I am quite pleased. You definately notice the difference in acceleration right away. The car just wants to run harder out of the box, which is nice. I think it really compliments the nature of an NA Z.

For reference, my other applicable power mods are:

TS ECU (flashed by AAM in Maryland)
Ultimate Racing High Flow Cats
Ultimate Racing Y Pipe
Fujitsubo Exhaust
UR crank pulley
Gruppe M carbon intake
Work Emotion wheels (18x8.5, 18x9.5 with 245/275 T1S)
Cusco RS LSD (set to 1.5 way, 60% lockup)
NISMO t stat
OS Giken Clutch with integrated flywheel (aluminum)


Coming soon - built heads with headers and cams

Any questions, let us know

 

Are you happy with your Cusco RS ?

 

are you happy with the Gruppe-M? how much does the Ram air scoop help? Does it give you a noticeable gain?

 

great review!

i don't know much about this mod,
what exactly does it do? (how does it get the car moving faster)
what are the downsides?
does the car feel different on the highway?
most importantly, how safe is it for the car?

 

Great review! I am looking to do this mod also. I bet passing on the highway just got more fun. If you don't mind saying, about how much was the total install, parts and all. If you're doin this you should do it right and not be cheap. I'm curious to what a tranny shop would charge to perform this install.

Don't forget to post your impressions after the 200 miles roll and you launch a few times. More or less whine? More driving impressions, etc.

 

Love the Cusco RS diff - nearly as my stock one was

Orange Peel - its going to give the same basic gains as nearly every other intake in all honesty - I got it based more on the aesthetics than anything else - plus its a good overall design and totally shielded from water.

durobred - do some searches..there are tons of threads on the final drive mod

Sponge - its hard for me to compare my installed price vs a customers, as we don't pay retail for the labor or components. I would budget around $1600 or so including all the seals, etc that I did, plus labor and the NISMO rear diff cover

 

Is your Cusco RS LSD set to 60% @ 1.5way?

 

Scratch that question , I just saw the answer in your stats. Sorry.

 

Great review Adam!
All the other OEM parts we will have availalbe through our website (crush sleeve, bearings, seals, shims, and pinion nuts)
The shims there is just no way to tell what you may need until you get in there. We have all the shims in stock now just wainting on the sleeve and bearings.
The gear noise is directly related to the offset/ backlash the FD is set to. A little more offset will let the rear end run cooler but you will get a little whine with it. Run it a little tighter and it will be quieter but may increase the temp.
With the race cars we run with a little more spacing to let the rear run cooler. (The 350Z/ G35 rear end will run hot on the track.)
We have 2 350Z in the shop getting 3.9's right now and two more complete housings awaiting the arrival of new pinion bearings to complete. Any questions just let me know and hope you enjoy!
You can expect 6-7 hour labor charge for the installation of the 3.9 final drive. If you purchase a Nismo LSD it comes with new side diff bearings and seals. It makes the install slightly easier.
Cheers
BJ@350EVO.com

 

Sounds good BJ - so I am ok with a backlash of around .0010 vs instructions recommended .0080?

Got my 200 miles on it, so I'll be posting tonight the events of my way home

After driving it today I agree with what was said - this is the final drive the car should have had from the factory

 

Great Review Z1. Thanks for sharing.

 

Ok guys, now that my 200 break in is done, I decided to let loose and see what the car can now do. Let me start by saying again that the car begs for these gears in NA use. With twin turbos, it would be a bit much. With a more mild mannered SC setup like HKS, I think it would work great.

Turned traction control off and pulled out of our building complex. As soon as the car was rolling and my foot off the clutch (middle of the turn onto the main road), I gun it, and the whole back end slides out...predictably, but its hanging out there. While this was possibly before, it never was from such low speeds. I am liking it I continue down the main road, shifting at around 6700 in each gear. The car is noticeably quicker than it was before the gears went in, which is exactly what I had hoped for.

The "whine" I described is there, though its gotten quieter....perhaps I am growing used to it already. Tomorrow we are headed down to E Town for the big Evo vs Subaru shootout, so maybe I'll get a chance to find out how it now stacks up against some of our customers rally monsters I wont be 1/4 mile racing this Z..that's what my other Z is better suited for, but I should be able to give some good real road impressions

Adam

 

Sounds good to me!

 

This is my next mod, looking forward to more driving impressions.


Laterz
Aceman

 

what is the stock gearing?

 

6mt is 3.5
This is the final drive that should have come in the track model.
BJ@350EVO.com