Has anyone done this to their car? What gear ratios did you use? Will it work for an AT? What will the AT FD ratio be if it's even available? I don't do 1/4 mile but I want gains in lap times around the track. Any input is appreciated.

 

Glenn you can put the FD from a 6MT into a 5AT. The FD for 5AT is 3.3 and for the 6MT is 3.5. I know a couple of people have done this on my 350z and said the car accelerated quicker with the 3.5, but you will lose some topend speed. I thought your car was a 6MT?
Derek
(Dyno car strapper )

 

any threads that show improvements?

 

I have a 05 6MT and im switching my 3.5 gears for 3.3

For FI cars this can be an improvement as you dont have to shift as many times in the 1/4 miles and makes first gear more usable.

 

I have 3.92's going in right now. Will let you know in a day or two. 3.3's to 3.5's is not worth the expense, in my opinion, better to put in a torque converter if that's the small step you want to take.

You have to get the 6MT diff, etc. to put them in the auto anyways. Teh same for the 3.92's, but you also have to buy the ring and pinion.

Rick

 

hey ismsolutions, did u see better times with the 3.5 final drive? I just purchased the 350z pumpkin and I hope it's worth the money. I am not for some decrease in time by .5 but .2-.3 in the quarter mile would make my day.

 

Ive got the 6MT lsd 3.5 in my AT5 . I can tell there is a big difference

 

how big??? I just purchased one today for 550 and I just want to reasure myself it was money well spent, lol.

 

OK...3.92's are in and everything I expected them to be. We first put in the 3.5's, just for reference, and they worked well...but they just didn't get the car out of the 4kRPM range fast enough. The 3.92's - well, another story. THE CAR ROCKS!

I raced a few local G35 6MT's, well mod'd, and beat the crap out of 'em. They never knew what hit them...especially from a non-FI Auto!

If you want the WOW in your car - you've got to do 3.92's! No questions asked - no prisoners taken!

80 MPH RPM is 3400 - 60 MPH RPM is 2400 - Gas mileage change = negligent.

You gotta do it...and do it right...the first time!

 

Nice. Have you figured out what your new top speed is yet?

 

I was wondering the same thing with tall gears like that your top speed will be affected bigtime. I won't be surprise if you tap out at 130 you will run out of gears by then. I don't do 1/4 mile runs I like circuit racing better maybe something less aggressive gears would work better for me. Thanks for the input enjoy your new setup at least there is an alternative than going FI.

 

I just like tearing away from stoplights. I never plan on driving 130 on a public road.

I swapped out the rear gears & differential on my old car (97 mustang) and it was like a new car... it was incredible.

Unfortunately with gas prices as they are today and our babies taking premium, it's going to take some time for me to risk the "negligable" increase in gas consumption. I noticed with my mustang that the "negligable" increase everyone was telling me about was actually quite noticeable.

Man I'd love to do this though...

 

I figure top speed is about 152 - I took a 136mph run last night and still had about 600 RPM to deal with. Fast enough...dont ya think? Not going to the salt flats anytime soon for a record!

Gas - I figure I lost 3-4 days a month - about 1/2 a tank shorter.

 

I have the 05 with sports package so if i wanted to change it to the 3.9 differential is that all I need? Can I still use my vlsd that was in there and just buy the differential instead?

 

Gears are the first mod I would do for any car...hands down. Then Intake and exhaust and pulleys....actually I would and did, do pulleys 2nd - I happened to do my gears after the other mods - as it was the plan this time around for other reasons.

To quote time to install - varies on the cars - If you have a G35 Coupe Auto - then you have to purchase the 6mt differential and the gears and have it all installed - properly. If you already have a 6mt - then you just need the gears. Beware of shims though - they are very hard to get and you will not know which ones you need until install time. I went and purchased all of the shims first - then had everything installed, then returned the shims that were not special ordered.

The average install time can be 2-fold - you need to have a shop remove the pumpkin and then send it to a shop that can do the gears and differential swap - if you don't have a place to do it all under one roof. This process is likely a 3-5 day turn-around and cost is about $250 to setup the gears and about $350 to R&R the pumpkin...an all in one shop would likely get about $500 for the whole job - NOT INCLUDING PARTS, ETC>

If you have to purchase the differential - you could buy new - but I would suggest you the whole pumpkin from a JunkYard - about $650 - this way the gears etc. can all be put together prior to taking the car out of comission - once the build is done - a shop could turn-around the pumpkin swap in a day or a little longer.

There are also differnet LSD's - Viscous and clutch/gear type. The Viscous units are the best for daily driving (OEM VLSD vs Nismo or OS Giken)