sentry65

iTrader: (11)

good to know, 167 mph might come in handy on occasion

SnakeBitten

iTrader: (8)

181?? Is this a mathematical conclusion based on gearing or has this actually been proven?...

Doh...I just reread the post and realized what was being said....freakin noobies lol....Im new to the 350z game fellas bear with me

BTW how drastic an effect would 20" rims have on the 3.9....If I understand correctly how rim size affects gearing, it would make it taller thereby negating the effects of the gear change right?..

dwnshift

iTrader: (1)

To give some people an idea......this gear was originally designed for Daytona Int Speedway on the road course with our GAC 350Z. It was the only track we used 6th gear at. This gear was desgined from our calculations to be the ideal gear for the fastest rack we raced with in the 350Z. I ahve psoted a gear chart on this forum before that show the differences in speed between a 3.5 R/P and the 3.9 with different RPM values.

Rhoads

Im seriously considering doing this and that chart is exactly what I need to see before I make up my mind. Would you mind posting it again or providing a link to it? Also just out of curiosity, say you swapped this 3.9 into a bone stock 350z. What would you expect 1/4 mile times to be? Thanks again

HockeyZ39

You guys are going to make me bankrupt!!!

sentry65

iTrader: (11)

yeah something I learned when I did my mods is not to believe so much in the hype of anything anymore

Everyone would review their new part saying "holy crap!!!! this thing is awesome!! it's a totally different car now!!! It sounds MEAN - it's unreal. It just pulls and pulls all the way to redline" yada yada yada


.....really, mods are pretty cool and fun, but they're kinda a rip off too. You might get a guy with a popcharger going "holy crap!!!!" and you might get a guy with a new forged engine and twin turbo doing the same reaction. You just really can't buy too much into the hype. People get excited and post their opinion and that's fine, but really, every mod I have on my car makes me go, "hmm well it's for sure faster" but never have I gone "holy crap!!!!" because of any mod I did - and I did most of mine all at the same time.

Maybe I have a high "Holy crap!!!!" tolerance
Anyway, after you do the mods, you just get used to them again and want more to give you your fix

jreiter

iTrader: (6)

Keep in mind that the stock rear end gear ratio is different between the auto and manual cars. So putting a 3.9 rear end in an auto will have different results than putting it in a manual. I don't recall what the actual ratio difference is, but it's been discussed on these forums quite a bit.

sentry65

iTrader: (11)

the auto transmission has different gear ratios


If you were to do it, you might do a valve body upgrade first cause you're gonna need some fast shifts

I think it'd be a little too aggressive, but no one has tried it yet. It might not be too bad

dwnshift

iTrader: (1)

I can email it to whom ever would like it......its an Excel spreadsheet..It cannot post it in here. Perhaps one of the moderators could post it as a reference sheet or something. I cannot find it in here in the "search".
Cheers
BJ@350evo.com

sentry65

iTrader: (11)

a screen capture of it can be posted though

press the print screen button that is to the right of the F12 key

then open up paint under Program Files-->accessories-->Paint

then select Edit-->paste

if it asks you if you want it resized to fit the picture, press yes

then File-->save

select jpeg as the file type

then it can be posted

dwnshift

iTrader: (1)

https://my350z.com/forum/engine-and-drivetrain/101777-350evo-3-9-vs-oem-3-5-chart.html
try this...found the thread.....
Follow to see the gear chart.
hope this helps!
Cheers
BJ

Rhoads

I asked Fredrick Nissan of Maryland if they would do it for me (they do alot of perf mods there). They quoted me at $1800 for install

The local shop I normally go to said they could do it too, but he has most of his experience doing this with Mustangs. Do you happen to have an install procedure for this final drive swap? He wants more info before we do it. Also wants to know if there any recalibration of the speedometer needed. He quoted me at $200 - $300 (his typical Mustang install price)

bamyi

iTrader: (2)

Always interested in mods that will help me accelerate faster, but i have an 03 6spd and my 5th gear grinds all the time. will this be a problem if any? Also i ntoice that for the 350z setup, the prices are not $800 but alot higher, am i wrong?

MustGoFastR

iTrader: (13)

I had the same problem with my '03 Track when I bought it a few months ago. Dealer replaced transmission under warranty, no questions asked. Regardless, the 3.9 rear end gears shouldn't effect this one way or the other.

dwnshift

iTrader: (1)

I would check with another place to do the install...we charge 8.5 hours to do the install @ $65 an hour. If they have set up a ring and pinion before on a Mustang or similar .....they should be able to do the 350Z. The most important part is getting the math correct for setting the backlash.
If you take a 350Z with a 3.9 to a dealer....they wouldnt know it was in there unless they drive them all the time...and take yours out for a "test" or they pull the cover off and count the teeth on the ring gear.
The newest version of the 350Z gear box now has more vibration dampening. Where the shifter cradle attaches to the tras. housing.....it now has rubber bushings there instead of a solid attachment.

seabass

iTrader: (1)

how hard is the install if I order a pre-assembled unit to swap in? can it be done by a average home mechanic?

does someone have a write up on the process?

Thanks

Rhoads

do you have any install instructions, plus he wants to know if the speedometer needs recalibrated. thanks man

EnthuZ

iTrader: (2)

Speedo will read normally with the 3.917 swap, as the speedo reads speed off the stub axels, which are "after" the 3.917 gear swap. Just remember that bigger #'s will occure sooner! Tire diameter WILL effect speedo readings though.

Rhoads

Thanks! one question down, now if there were just some install instructions that I could give to the guy who would be doing this for me Id be set. Do they come with it by any chance?

dwnshift

iTrader: (1)

Instuctions for the swapping the gears come with the final drive.
The rear pumkin itself is a fairly easy swap. Just make sure the shop doing the work...has set up rear ends before.