i didnt really mean "lost" per say. More like its not accurate anymore. Or so ive heard from everyone who changed their FD.

I personally think the FD swap needs to be done depending on what your requirement is, on which track/road course or whatever..

while the shorter FD increases 1st gear launching and give you out of the hole G force, you need to remember that you will have to shift earlier, and depending on what kind of power band you will be sitting in which gear, the FD might actually make your car run slower because you will be out of your power band earlier, just as you would be in the band earlier. Depending on which gear you will be in most of the time, this may help or hurt your results. But shorter FD generally makes the driver a bit more busy/alert which is always fun :D and I think that helps with lap time.

Back in my 350Z days started almost 10 years ago, people were craving about 3.9 FD set (stock is 3.5 in 350Z) and I got that swapped out when I was doing the LSD. The track I went to quite regularly was pretty much spot on for the 3.9 because I could run in 3rd gear all the way in the areas where I had to use 2nd and 3rd gear. But in some other cases, I had to shift a lot more and it seemed to eat up my time. With shorter FD It seemed more frequent to fall in to the band where it was awkward to either stay in gear or shift up.

You need to remember, while a car with shorter FD will accel faster when compared to a stock geared car gear to gear, 3rd gear to 3rd gear for example, shorter car's 3rd gear will be accelerating slower than stock cars 2nd gear and if you happen to shift into 3rd where stock cars can stay in 2nd - you are losing.

Not sure how 4.1 would feel.. probably a bit too short? I found 3.9 somewhat short already, but that's compared to 350Z's stock 3.5 FD. However the extra HP of 370Z probably will make it feel a lot shorter.

Funny how we cant really settle with the stock settings and always try to make it slightly different in the hopes of improvement. Even if the cars came with 3.9FD people would still try the shorter gear :D

I gotta try the same track with my 370Z, only recently got the car and haven't had a chance to visit a track yet. :eekdance:

Hey man quick question does your SRM and cruise control still work with the 4.08 FD?

Don't think you're going to get most of those posters to answer given how long ago this thread is from.

To answer your question, the SRM requires a re-calibration via ECUTEK or Uprev to consistently work with a 4.08 FD set.

Didn’t realize this thread went over 3yrs without a comment...I know if you’re running stock diameter tire’s-your speedometer won’t be affected,as wheel speed sensors are on the output shafts of pumpkin cover-reading speed of stub shafts/ from the toner rings.

Only issue I've had with SRM since going to 4.08 was it's off by like 200 rpm. Still works fine though

Track guys have had it randomly turn off. Being off by 200 RPM also isn't ideal. Shouldn't hurt a street car however.

Did 4.08s on mine and SRM was totally off, very noticeable. and quite annoying. Blips were off by a fraction of a second and simply turned it off until Ecutek tune. Tune took care of it and it is fantastic. 4.08 makes it funner :) Maintaining the same driving style, my mileage dropped by 4/10s of a mile per gallon. Overall, a great mod for those staying N/A.

So you can fix the SRM issue with Ecutek?

Yes.

I don't have SRM, but after doing 4.08 install on my quaife I can honestly say, that's how these cars should come stock lol

Big thing to keep in mind with gears, especially 4.08's is your gearing for and against you. At speeds over 90mph, you'd be in the same gears for a shorter amount of time. There would be 10, 14, and 18mph per gear that you are sacrificing to the next higher gear. For At those periods, the 3.69 will be more beneficial. The only way to get around this is compensate by rpm. So 4.08's really make sense if you can rev the engine to 8000-8250rpm. That implies that you have more aggressive cams, oil pump gears, ad damper at a minimum. It would also be recommended to replace your rod bolts and look into running a slightly stiffer valve spring on the VVEL side to prevent spring attenuation. That would make for a pretty Nasty NA Z, but costly. Anything over 8500 would need a new rotating assembly too.

On the track, 4.08's can be great for pulling out of a corner, but a PITA on the straights or high speed turn where you find yourself between the right gears.

Coming from a 3.69 hands down I won't be coming back. I have a great street car and told Seb keep the old gear.

Any one know the top speed of each gear in the manual 3.69 final drive? Trying to see where gear shifts occur of going to a 4.10

Look in my thread. It was posted by Mr. Squeeze. He compared 3.69 to 3.3. It is around page 100.

Now that the MT Nismos come with 3.9 from the factory, has anyone had more experience with them? I'm on the 3.62 ratio with factory VSLD, and having a tough time deciding if it would benefit me.

Street car, 1/4 mile for the fun, and HPDE type of events
NA for the foreseeable future, N20 (nitrous) if I start chasing ETs at the strip
Daily now, but hopefully retired to weekend car by end of year
Wavetrac diff for planned upgrade
My driving makes MPG a somewhat moot point :)

Thoughts, everyone?

There is not enough difference to make a change IMO. If you want gain more then run an 18" wheel and tire combo.

Sent from my SM-G965U using Tapatalk

Huh. Didn’t think of that. Muchas gracias. :)

Are 4.08 gears avail through Nissan/Nismo or only avail aftermarket?

There are Nissan oem ring gears in 4.08. I'm still running mine and depending on what you plan on doing with them, they're a great option. I find more benefit a lot of the corners I find myself in. At times, I find where I need to shift up so I don't run into the rev limiter mid corner. If you ever do Road America, I think a 4.08 would work perfectly if your redline is at 8000.

Thank you for the reply.

It seems a few Z sites are showing the 4.08 ring and pinion as part# 38100-0C760. In the Nissan parts catalog, it lists them as 2005-2020 2.5 frontier, manual trans, ring and pinion set. Very cool.

Here is a Video with everything you need to know about Final Drive. It is in German, but you can use the Autotranslate on YT.

https://m.youtube.com/watch?v=3fR6vg2KZ_s

Maybe it helps anyone?

Bringing this thread up instead of opening a new one..

Lately I am thinking that I want the Z to have more power, i.e. more low end torque. I was thinking about various supercharging options, but that seems like a handful, expensive, and a bit risky move. Then it occurred to me that a final drive swap would actually give me exactly what I want. I would get the more "lively" feel with the car, the engine would be quicker to rev up with the first 3 gears, and I wouldn't actually sacrifice a lot - losing a bit of top speed and a bit higher cruising speed. But the main gain that I see here is having a much livelier car, that would probably feel like having some extra 30-40hp within the first three gears, as the gearing between stock 3.53 final drive and the 4.08 drive is more than 15%, which makes a big difference.

So after further research online, I think I'd go with 4.08 or 4.11 final drive, whichever I find to buy.

So my questions is more for the ones who already did it....how complicated was the install? I think the biggest challenge is getting a press for handy use, as it seems like the pinion gear, bearings and preload are the most difficult thing to get right. So I'm thinking that I'd maybe even pay someone to do it.

Also, which parts do I really need? I was thinking that beside the pinion and ring gear, I'd take new bearings for the pinion, new bushings, and probably new diff oil. Last year I changed the axle bearings, so I'd keep them.

Thanks for any input or thoughts.