http://www.z1auto.com/prodmore.asp?m...ne&prodid=1726

Central 20 gears for under $500 For those that have been on the fence, I think you guys should be all over this!

 

nice find..........if only they worked on the AT

 

I bet they mean it will fit only in a 3.5 MT pumpkin...

 

Sweet. Maybe the price from 350evo and Nismo will come down now. Might actually consider getting one of these now. Any idea about the build quality from Z-1?

 

Will it loose the Luxury Comfort ride quality to the G if u get this installed? Cuz i really want one but dont wanna loose the comfort quality.

 

you will lose the cruise control. you will lose gas mileage. you will gain huge performance benefit (by all accounts anywhere from 0.5 to a full second in the quarter mile).

that's about it.

 

Wow, I'm definitely interested in this.

Can someone verify that the only thing needed to install these into a sedan is a 3.5 6mt pumpkin? Can I use my existing LSD (2005 sedan)?

 

Hardcore myth. Maybe .2-.3 if you're lucky. It will feel like you gained about 50whp though because of the increased torque multiplication. People need to understand that the 3.3 gear for the 5AT is already pretty deep and that it is quite possible to over gear a car and make it slower.

 

There is no torque multiplication (akin to a torque converter) - it's just a gear ratio. I'm just reporting what someone else got with a 3.9 final drive on a 5AT (with a TC added in at the same time I believe).

It's only a myth if there's no evidence to support the performance gains and there are. A search on this site and/or my350z.com for "final drive" should prove useful to those interested in getting some first hand experiences.

 

Changing a final drive is a trade-off like anything else. For accelerating from a stop (like for 0-60 or the 1/4 mile) you will of course see only benefits as you're putting more force to the ground continuously.

But if you accelerate or "race" starting from another speed (like 50 mph), then the difference is up in the air. It depends on who happens to be in the lower gear at that instant. Whoever gets the jump for the increased force to the ground in the lower gear will win. When the person with the 3.9 is now in 3rd, the person with the stock gear will be in 2nd and putting out more force.

I did a ring and pinion swap in my last car and have done detailed simulations of both configurations, and it really depends on what the car is used for. Basically, if it's a 1/4 mile car, then go for it. Otherwise, leave the stock gears. I can post some plots clearly showing this trade-off if people are interested.

 

^ Please do when you get a chance, MechEE.

 

3.9 over stock



Central 20 is an old skool JDM company and I would not doubt their quality whatsoever. About applications, it will fit any LSD that the 350evo will.

 

That's just a ratio chart. Overlay force to the ground versus vehicle speed and it gets interesting. I'll try to generate the charts later tonight.

 

Just wondering if there is any way to get the cruise control to work properly after getting these gears?

 

Does anyone have 3.9 final with Forced induction?