It takes approximately 4 to 5 hours if you just replace the ring and pinion. I kept the stock LSD. My installer charged $400 for the installation plus the gear oil.

If you replace the LSD it can take longer unless you get a package that includes the ring and pinion and LSD already put together.

You won't be able to see any difference under the car.

 

have any track numbers with your car? just curious what that kind of N/A setup with gears can do in the quarter.

 

Nexx,

Sorry but I don't have any quarter mile times. I have never taken the Z to the dragstrip. I prefer road courses.

Quite frankly I am not sure the 3.9 makes that much difference in 0-60 or quarter mile times, although I have seen some posts that it does shave a tenth or two. First gear is even shorter than stock with the 3.9. Where the 3.9 shines is accelerating out of a corner or accelerating from a roll.

The 3.9 was my last major mod. Before I got it my car pulled hard with my NA mods. I was surprised how much harder it pulled after I got the 3.9. A friend of mine got his 3.9 before me. His car has only an intake and lowering springs in addition to the 3.9. When I first rode with him his car felt almost as quick as mine with all my NA mods, but without the 3.9. Not anymore.

 

I understand this is my second post due to my time involved with reading mainly, but i believe this tread needs to be a sticky do to all the extremely useful information it provides about drivetrain in general. Does anybody else agree? Vic

 

So what would be the best setup for a Vortech? 3.9 final gear and a different limited slip seeing that people think the stock one is junk? Do you really have to drop the pumpkin to do this? What are the good brands out there? Subscribing

 

Yes, you have to drop the pumpkin and disassemble it. The ring gear surrounds the LSD, inside the pumpkin. No way around it.

Choose whatever LSD suits your purposes best that is compatible with a stock 3.5 ring gear to replace your differential. Quaife, ATS Carbon, Kaaz, Nismo, etc...

 

Generally a 3.9 ring and pinion is not the best set up for FI. It works better for NA applications. I would think you would want to stay with the stock ring and pinion if you go FI because the gearing will make the car even harder to launch and drive in the lower gears.

As for the LSD it depends on how you use the car. The stock LSD is fine for most street applications. For the track there are several brands out there including the Nismo, Quaife etc.... As with any mods there are tradeoffs with aftermarket LSDs.

 

For FI applications some people like to use the 3.5 ring and pinion from the automatic.

 

Isn't the auto a 3.3 ring and pinion? The OEM 6 speed is a 3.55. But you are correct in that some with FI have gone with the auto's ring and pinion. It seems the more power one has the more likely that would be the case.

 

Sorry for the noob question. I'm assuming your speedometer will be off if you change the gear ratio?

 

Now...wait a minute...Quaife's diff is a great route, and no doubt VERY high quality, but I think that the choice to go Quaife is because it is a VERY different diff, and this is almost apples+oranges(?)...
I am in the market for a new LSD in BOTH of my cars, and a road racer friend actually tried to steer me AWAY from a quaife or similar Torsen type diff. They behave quite differently. Some prefer the break-away characteristics of a more conventional clutch-type like the Nismo. I however was interested in the longevity of a Quaife or Torsen diff especially when compared to the fall way performance of a VLSD with stickys!

Comments?
j!

 

No your speedometer will not be off by changing out the gears. In the 350Z speed sensors don't have anything to do with the gears. I believe speed is measured through the ABS system in the 350Z.

 

Lets not forget, while the 3.9 is definatly a great mod, when combined with the lightened drive train combo it really shines (ie tilton combo, UD pully sets, drive shaft if our wasn't already so kick ***, etc).

 

Yes, 5AT uses a 3.357, 6MT uses 3.538 gear ratios. The decision is mainly stemmed from a desire for better launch control with the high torque engines. My qualms about that is it reduces power output in all gears. You can spend more time in gear, but its in effect, a torque reducer, just like doing the shorter gearing is a torque enhancer. The concept goes both ways, just a matter of what you really need.

Yes, wheel speed sensors to be exact. They send the signal into the VDC / TCS / ABS controller which then passes it on to the other systems via the CAN communication.

All depends what you want from the car. My car will still be my daily driver, so it'll see much more street time than track. The way in which they operate is inherently different, and each one has their pro's and con's. The only gripe ever leveled at the Quaife is that when you tripod the car and lift a rear wheel off the ground, it functions in a similar manner to an open diff.

I've previously done a pretty exhaustive comparison of the pro's and con's of each and why the Quaife was a better choice for me, albeit, not on this site. Out of respect to the site owners I will not provide a direct link to a competing forum, and because I have an agreement with the owners of the other site, I won't reprint that information here. If you interested though, it has been mentioned by other members already this thread.