I have been looking into getting a 3.5 final drive into my n/a '06 5AT for a while. Now, when i'm ready to do it, I see that mynismo.com offers a 3.7 ring and pinion set. http://www.mynismo.com/products/?id=5568&rsku=21792

Has anyone installed this 3.7 on their 5AT? If so, any regrets as far as driveability or mpg goes? Also, is there any tuning involved after installing a 3.7? I know that installing the 3.53 requires no tuning but you never know...

I appreciate your input.

 

Steady cruise MPG is ~~ to engine rpm less any improvement in volumetric efficiency. Engine life is some multiple of average rpm so expect a decrease in end point life.

A decrease of 10% in MPG and 10-20% in life might be the result of sustained higher rpm?

 

I have one on order (not the Nismo, it’s an OEM 3.692 for a Frontier I think) and will be installing with Quaife either next week or the week after (depending on when the parts arrive)... I'll let you know impressions when its complete...

 

thanks, i'd appreciate that... i know the performance gains are remarkable but just wanted to know if any extra tuning was involved or any problems came about.

 

There's no "tuning" to speak of, just proper installation... It's just the ring and pinion gears in the rear-end and an aftermarket differential... I'm expecting problems but hoping they are minimal... Already had a setback in getting the FD, but sourced from a different vendor and waiting for parts to arrive next week sometime.

 

To calculate the gains in aceleration in each gear calculate the % of ratios [amount increased] and take the cube root of the number.

A 15.6% higher ratio will yield ~~2.5% [+-0.25%] faster acceleration in each gear.
Assuming nothing is wasted by any tire slip or spin.

An expensive 0.3 seconds in a {NA} quarter that keeps on giving at the gas pump.

 

Dont do it if you dont mind getting about 175-200 miles per tank.I did the 3.3-3.5 and while the performance increase can be felt it is not worth it overall.Trust q45tech on this and if you wanna swap rear diff,s with me im ready.

 

I'm not real concerned about gas mileage... I drive a company vehicle mon-fri... I'm in an AT G sedan and only avg 18 mpg anyway. 1 or 2 mpg less isnt going to make a diff for me.

Like many mods, they all aren’t for everyone... I'm looking forward to this one though! Not thrilled about cruise control going away though (from the shorter gears)...

 

yeah, i'm not concerned much with MPG either. although my Z is my daily driver (hence the AT,) i get 23-24 mpg average. Even if I went to 20-21 mpg, I still wouldn't mind if in turn I got a bigger kick in the *** when I slam on the pedal. Gas is cheap in america anyways so I feel that i'm still ahead of the game when compared to, say, greece, where I am now and am paying well over $4.50/gallon.

that being said, my main concern is with any problems the FD may cause with the AT, and any regrets people have had after installing it.

 

I have a 3.5 swap on my auto and get 22.9 MPG and about 390 miles to the tank. 3.7 will be significantly lower. Oh and i have no regrets on the swap, it took 1/2 a second off my 1/4 mile time

 

Are you F.I. or N/A? Are you shifting manually in the 1/4 mile or are you in full auto? If your manually shifting what gear do you hit the trap at?

 

+1

 

Going to the 3.7 from the AT 3.3 should be equivalent to going to the 3.9 from the MT 3.5. I have the 3.9 in my MT and it's the best mod I ever did. My city milage (90% of the driving I do) actually has increased b/c I find myself shifting up into taller gears sooner and staying in them longer. The slight drop in highway milage is more than made up for by this (and I still get 24-25 MPG highway). As far as how noticable the mod is, that can be a bit misleading, as the gains are perfectly kinear accross the powerband in every gear, so it's not like one of those mods you slap on and you feel some extra pull you didn't feel befor in a particular part of the powerband. The car feels the same, it's just faster. Acceleration gains are more in the 10% range in every gear, BTW. If you have a non-rev-up engine, I'd also recommend a reflash to raise the redline from 6600 to 7100 RPM; this helps with the shorter gearing if you run the RPMs out alot, otherwise, it isn't neccessary.

 

I completely agree !!!

 

You sure that just isn't from the way you drive?

I have the 3.917 on my 5AT and if I do nothing but short trips around town w/ little to no highway driving, I'm about 15-17 mpg, and average 250 gallons per tank. If I do a lot of highway driving, I can average 22-24 mpg and get about 375 miles out of a tank. I think I averaged 21.x on my round trip from NJ to Fontana Dam, driving the dragon for 4 days, cruising to Charlotte, driving around town for a day, then to VA Beach for another 4 days of vacation and cruising around town before coming home. This included my fat *** for the trip down, picking up my girlfriend at the airport in Charlotte, all our luggage and hauling over 100 lbs of a AP Brake F/R kit back from ZDayZ. The car was probably over 4300 lbs with everything in it.

FWIW, the 07 G35 sedan uses the 3.692 gear set and they have the same transmission ratios as the prior 5AT models.

 

With this mod do you end up re-using a lot of parts? I know i lose cruise control, but what about traction control and VDC or LSD? do i have to purchase other parts to keep these working with an upgrade 3.7FD

 

Can you keep the stock 3.3 pumpkin with this or do you need to upgrade?

 

the only experience I have with swapping final drives is with an '05 Mustang GT A/T, where we swapped out the ring/pinion for a 4.10 final drive ratio. We did not have to change the pumpkin, and ended up using all of the OEM already-installed parts for the rebuild excluding of course the ring and pinion.

However, I would like to hear from someone who has actually installed a 3.7FD to make this statement correct. The performance gains on the 4.10 were very noticeable while the car was N/A, but since it now has a Vortech SCer, it's a bit of a pain in the *** to drive.

 

Have you used this mod at autocross or at a track day? Wondered how corner exiting improves? I can see how it would help straight line racing but am interested in the curves. Thanks in advance for your response.

 

there aren't too many 3.7s that I know of... Andy from Performance Nissan did it, and I think he posted a review... there may be others but not many... I will have mine (with Quaife) installed within a week or so and jonnylaw is doing the same thing in an MT... so there will be 2 impressions here soon