[QUOTE=dwnshift]Instuctions for the swapping the gears come with the final drive.
QUOTE]

Thanks alot

 

Any shot at a group buy for the 3.9???? (sorry I had to ask)

 

Sorry....
BJ@350EVO.com

 

No problem, cant hurt to ask right? LOL

 

What is your RPM at 70 MPH in 6th gear?

 

i dunno, like 3000

 

if you have an OEM LSD, should i upgrade to a nismo LSD when i upgrade the gearing? i dont drive my car too hard... not all the time .. would it be okay to just keep the oem and get the gearing alone? what are the things i will need to buy and how much? i know the gearing with an assembled nismo lsd is about $2300.. so maybe this will be considerably cheaper? anybody know places in the san jose or hayward area that install?

 

If you are not doing a bunch of track days...........I would stick with the Viscous if thats what you currently have. A clutch type diff will make a diff at track events though. Depending on how many miles are currently on your car.....I suggest doing pinion nut, crush sleeve and pinion seal at the least. You can re-use your current ring gear bolts or some people have bought new ones......Putting new bearings helps make everything new...but isnt absolutley neccesary.
you can always drop me an email
BJ@350evo.com

 

Ok i been reading and reading and reading. I am interested in getting the 3.9 for my 5AT 350z. Ill have to wait tell i get my car back from the repair shop, and sell my old nismo exhaust. And take care of the diminished value.

Question, i read most you have the 3.9 in a 6MT, Anyone here have the 3.9 in a 5AT? and how does it feel?

Thanks for the info

James

 

Does anyone have any before and after numbers in the 1/4 after installing this mod? I was thinking of saving for FI but i'm scared it will be a mechanical nightmare and would much rather stay NA. Thx.

 

zillinios said his 1/4 time was the same, but trapped 2mph faster

I think a few other people said their 1/4 mile times went down .2-.3 sec as long as they had an ECU flash with 7100rpm redline so they didn't have to shift into 5th

 

basically, you're driving constantly in high RPM.... I guess ECU reflash is much more effective because you can raise your RPM up to 7.1 which meant you can still driving up to 62MPH under 2nd gear

 

This does sound like an awesome mod. Just sucks it's out of my price range right now. Guess I outta pay for the car first, .

 

if the only gain is a 2mph faster trap, then whats the point? you can get a faster trap by having bad traction.

.2 to .3 better times is not worth the 1200+. i got .6 better 1/4 time with just 1k dumped in the torque converter. now that is worth it.

dwnshift, you sell the 3.9's and install them?

 

I don't think people buy the 3.9 final drive for drag racing.

It's more of a road course part. It'll give you more accelleration out of turns which will give you a higher speed on the straights. That higher speed eventually adds up lap after lap, straight after straight.

In the 1/4 shifting points is a huge deal. Each shift costs you like .2 sec or whatever. If you have to do 5 shifts instead of 4, that counters .2 sec of your gain.

On a road course, you're not racing down the 1/4 mile. Each straight is different. You're kinda playing the odds either way whether you have to shift say 3 or 4 times on a given straight. Might as well have 10% more accelleration

The 3.9 might only add maximum of .2-.3 sec (if you have a raise rev limiter) on the 1/4 mile, but on a road course, it'll gain you like 2 sec a lap which is huge.


IMO, this gearing should work fine with the vortech or ATI supercharger given that you have big wide tires and an LSD, but won't work well with any other kinds of FI kits

 

hmm. interesting. i barely get into 4th gear in the 1/4 mile. im talking 200 feet or so before the end. wouldnt a raised rev limiter help me more in this situation then a 3.9?

i wont have to shift into 4th and i'd get .2 back. that and the fact that ill be that much closer to my power band after every shift. right?

oh and thx for the pos. rating sentry.

 

well if you have an AT5 Z, I wouldn't do the 3.9 FD. It probably wouldn't help much at all. I was talking about a 6MT Z and it's shift points with the 3.9 FD

in the 1/4 mile, the 3.9 miiiiiight be useful if you're just barely shifting into 5th gear. If you're going to be shifting into 5th gear anyway, might as well have 10% more power right? It'd severly limit your top speed though since the auto's FD is 3.3 to start with. So it'd limit it by roughly 16%. If you have a reflash though, you'll regain some of that so your top speed will be i dunno 150mph? - just a guess

Yeah I think a raised rev limiter would help you out. Just be careful going to 7100. Zillinios thinks he blew his engine by reving to 7100 a lot on road courses - which is way more brutal on the engine than a single 1/4 pass. I don't know much about autos dealing with a 7100 rpm limit though - not sure if the ECU freaks out or whatever. It'd probably be fine

no prob on the rating, thanks again!