^^ I have one that I'm going to sell in the next few months LOL...

I have an 04 base model that came with an open diff, at the time, I found someone with a 3.3VLSD up for sale and jumped on it. Knowing it would give me better traction off the line and better gas mileage for my high mile commutes. Well, it did both But I have found that I am just as heavy on the gas as I was with my open diff, so the better gas mileage factor is out the door now, LOL! So... I am in the process of building my open diff into a VLSD with 3.9FD. I already have the axle stubs, in the process of getting the VLSD, and need to purchase the 3.9FD. I noticed a slight loss in performance jumping from the 3.5 to 3.3 (-5%). Currently I can cruise at 78mph at 3k and thats with 25.4" diameter tires. I am looking forward to this 3.9FD setup, since I am n/a and plan on staying n/a due to the desire to keep my Z foeverrrrrrrrrrrrrrrrrr This new setup should yeild a 15% gain over what I currently have, which equals a lot more fun!!!!

To the original poster, I say do it!


Zquicksilver

 

Alright Im pretty much sold (original poster btw) and as soon as I save some extra side $ ill be gettin em. So is the central 20 kit that Z1 performance sells the best one to go with, or are there better ones out htere?

 

The Lose of cruise is not 100%, I have heard mixed reports from several folks.

 

How does it cause the crusie problem again? Anyone with the 3.9 ever experience that?

 

So is the Central 20 the one to get for 3.9 or is there a better one out there?

 

I think this is only ever a problem with AT, not MT.

 

Installed the 3.91 FD. It absolutely is my most effective performance mod to date. It should have been my first mod. I highly recommend it to those who want better than average performance without going FI.

 

How hard was it to install?

 

lol 3 pages of nothing but good comments on this thing...To the OP- Just buy it already, you know you want to...haha

 

OP- if you dont plan on going FI and dont care about speeds above 160+, then the 3.9 FD is the most bang for your buck mod you can do on a NA Z. Go for it. You will have slightly lower gas mileage and will have to shift sooner than before but the acceleration u get is worth it. Combine the 3.9 FD with a lightweight flywheel(like tilton) and clutch with a 1.5 way lsd and you wont believe how responsive the drivetrain will be. You wont be disapointed with this mod...trust me.

 

I plan on gettin it in the Feb time frame lol. Wat all is needed to install it? And how hard is it?

 

How much time would be cut of the 1/4 mile time with these 3.9's? Let's say a stock Z runs a 14.1. What would this do? 13.9? 13.7?

 

The gears will be slightly more than 10% shorter, so your acceleration should be approx 5-10% quicker. I'd guess a stock Z would hit around 13.3-13.6 with this mod.

 

wren, do you have 3.9 fd?

 

No, but I've thought about getting one... I've done a lot of research on them and it looks like a great mod. $$$ is my limiting factor.

 

So anyone on here know how hard it is to install this thing? And does the kit from central 20 come with any directions?

 

jtgli

Its not quite a DIY, especially if you have to ask. Some have done it themselves, but I would not recommend it unless you have expertise in setting up gears and the tools necessary to do so.

See this thread for someone that has done it themself

https://my350z.com/forum/showthread....ighlight=cusco.

The price to have it done professionally I have seen quoted on this board from $300 to $700 - depends on where you are and what the local expertise is. Cheaper at places that do it often. There was only one shop in my area so I was at the mercy of their pricing. And that doesn't include the price of the extra parts (seals, bearings, bolts, nuts, sleeves).

Hope that answers your question

pp

 

No I am having a shop do it, I jsut want to know what you explained, whether or not there would be other parts involved and how long it could take.