On Sam's suggestion I figured I'd start this thread lol

So here's the thing...with the gear swap it's pretty clear how to go about doing it...you buy a M/T diff from another G...figure out the driveshaft problem in the couple ways you can....and if your getting 4.08s..get the gears in...and your good right?

WELL...That's what's not so clear...does anyone have a solid answer as to if the ABS, VDC, and Traction Control are effected..it had been mentioned that it may...and IF so...how to go about fixing the issue?

it was suggested that the TCM and ECU wouldn't be communicating properly and that the right dealership tools could fix these issues if they arise...anyone that could shed more light on these things would be awesome.

The speed sensor code that can possibly be thrown.... seems to be hit or miss (it seems as though a tune can fix that issue however)...as does the cruise control...some lost it while others didnt..
I have seen some threads that say they are related to each other and that an EcuTek Tune fixes either.

I have noticed that people getting the 3.9 Gears or those simply sticking with the 3.69s in the M/T diff...don't seem to complain of any issues so if this is strictly a 4.08 problem that'd be great information to have out there

Anyone with gear swaps please chime in with your experiences after install!

Some solid information will help alot of people thinking about gear swaps....the information is very scattered.

 

^108 views lol no one?

 

Here's a recent gear swap, might shoot him a PM to reply to your thread
https://www.myg37.com/forums/engine-...installed.html

 

Thanks for the link newt just shot him a PM

 

I swapped to 3.90 gears in my 7at and didn't lose any of the aforementioned functions of the car. there was a code that was thrown but I can't remember what it was, seb just tuned it out via ecutek. I have all functionality of my cruise control, but I do know that some have lost this ability. the new racerom 2 from ecutek can correct the loss of cruise. that has been my experience.

 

Thanks for replying Conk appreciate it...and that's kind of why I think this may be an issue strictly with the 4.08 gears.....if the suggestion that the TCM and ECU have problems communicating with the M/T Diff installed..is true...it would kind of make sense that because the 3.6 and 3.9 Gears come stock on different models (and it's not like they have different ECUs in each model) those gear swaps may not have those issues? Unless it's the EcuTek Flash fixing it just as it does with the Cruise Control

I am probably going to do the same gear swap you did at Specialty Z with the 3.9 gears...calling tomorrow so I will ask about these things and update the thread with the information I get!

 

As far as any of those mentioned problems, I have none.

But, I have a 6MT. So for me, it is exactly as stock, just better acceleration.

I have functioning cruise control and everything else is normal.

But like I said, I have a manual transmission, so this doesn't really help you.

I may add, that during my research for this mod, I determined the 3 common problems with automatics that swap out for a manual pumpkin. The first being loss of cruise control - this is a common problem, however for some reason not everyone loses cruise.

Another problem with the auto 4.08 swaps is your car will throw a code. Due to the fact that the vehicle is no longer receiving the rpm input from the auto differential.

And the 3rd common problem for auto Gs is that the rev-match function often ceases to work.

I don't recall reading about problems with ABS or traction control.

My swap was done by Specialty-Z in Chatsworth, CA. Sebastian is who I dealt with from start to finish. Very helpful and very professional.

Specialty-Z is a great shop with a lot of experience and expertise.

Specialty-Z, Nissan 300ZX Specialists, Nissan Z Specialists - Home

sebastian@specialtyz.com

 

I've had my 3.693 swap on my '11 7AT for a little over a week now. I swapped in a whole pumpkin from a g35 2007 S model (all S models, sedan and coupe in 2007 had 3.693 geared VLSD pumpkins...and no g37 label attached so $150-200 cheaper on the used market than equivalent whole pumpkins --- eg $200 shipped, had 60k miles on it and very little surface rust..much less than my '11 diff).

I know the OP inquiry was about 3.9 and 4.08 gear swaps and after effects commonly found with going to those, but I thought my post might benefit others interested in this subj matter. It is the best bang for the buck mod, why? Because increased mechanical leverage can't be argued with-- it impacts the car across all the power band and just is a nice kick in the pants off the line for our heavy cars. Much better mod than say a decent intake and exhaust (even w/ a tune after..and how much money spent would you be at?).

1) no loss of cruise and as some said you might lose it about 80-82 mph, I checked into that.. no problem setting mine at 85 mph.

2) No code thrown, I've done a lot of spirited driving in the past week- I also put whiteline bushings in at the same time so along with vlsd and 3.69 FD being added compared to my oem setup..a firmer overall, more connected driveline resulted from the bushings swap (my main bushings wasnt leaking and in fact, was in good order before the saw-zall got to it lol).

3) Rev-matching for my 7AT when in sport mode still works as always...doing it's job on off-ramps and quick slow downs. I have a tanabe medallion catback, and if anything..the higher rev range through the gear changes and kick downs are even more harmonious and entertaining to my ears than when I had 3.3 FD.

for the record, I did receive a diff that was out of a 07 5at sport... it's easy enough to swap the flange (from a four hole to a three hole flange) but considering the option for a diff with a three whole / triangle flange was available.. I went ahead and pulled the trigger.

Used diff = $200 Shipped
Mobil 1 Gear oil = $22
WhiteLine Bushings = $95
Labor (friend that had experience swapping pumpkins and bushings) = $150 and a pizza

Total for swap = $472

We did the swap in my garage and w/ basic jackstands.. I am really grateful that my friend had his tools of the trade (industrial HVAC repair) as one stubborn bolt that went through the different side bushings, holding it and the top hats/bushings in place started cross threading on itself when we removed it... we managed to get the bolt off and reveal that 30% of the threads had sheered off. Ended up being an easy fix with his tools as he re-threaded/cleaned the hole and bolt threads w/ a die/tap.

We took our time and it was a 6 hour endeavor all said and done. A lift and proper tranny jack would have shave an additional hour or so off.

Love the discussion and info shared thus far...thanks OP!

 

I did my swap for $350 labor. I have a 6MT and I didn't lose functionality. Def more acceleration with a disrespectful 1st and 2nd gear. 275/35/19 sized tires def needed.

 

Well thanks everyone for the posts I appreciate the replies. The more I read about everyone's results and how seemingly simple this mod is for the gains you get is really exciting.

I have been waiting on my tuner to get back in the shop he has been out.

I am currently trying to work through him with Uprev to see if the Speed sensor codes, cruise control etc. can be fixed with their software.I talked with him this morning and he is currently waiting on return calls. Ecutek is a possibility but they have never tuned a Nissan with ecutek...and the closest tuner that will do it is Specialty Z...they are about 400 miles away haha...so I'm trying to get it done locally before I commit to that long drive. My tuner did say though that if uprev is a no go we may look into EcuTek...so I will keep the post updated lol

Also contacted Specialty Z and contrary to some of the things I have read 3.9 gears are still pretty easy to come by and he can get them np..so there is no need really to hunt for a vert differential. Just swap out the 3.6 gears in any M/T diff.

I do have another question which would also be helpful to have out there if anyone has experience with this....my plan is to install a one piece driveshaft....since the M/T is larger I have gathered the driveshaft will be a different length..am I correct in assuming I would just order a manual transmission driveshaft...or would it need to be custom made? This is the only thing stopping me from starting to order the parts so some help is greatly appreciated!

Again I thanks to everyone for sharing the information! It is helping alot!

Update:

You need an auto driveshaft if you have an auto. No way around that. So that requires either swapping the flange on the M/T differential...or a custom auto driveshaft with a M/T flange on its rear (if they will do that...that's my next step)

 

Maybe a pointless additional question but out of caution I'll ask haha...will doing the gear swap cause any problems with smog/emissions tests?...reason I ask is because if the swap makes it throw codes...the test is done mostly through the ECU...will that cause any issues? I would assume that once the tune clears the codes it will be fine...but just a thought I'd throw out there lol

 

'will doing the gear swap cause any problems with smog/emissions tests?'

There should be zero impact on smog/emissions related measuring sensors/tolerances.

Aside from when your car is at a certain MPH, it will be a higher RPM...thus the engine working slightly harder and burning more gas as a result. As long as fuel/air/gas ratios and mixing was good to begin with before you do the diff upgrade, all should still be the same.

 

Okay cool thanks man. Yah I don't want to spend all this money and do all this work just to fail smog in a few months haha that definitely wouldn't be cool lol so just wanted to check

Just ordered my differential. I found a 2013 coupe M/T locking diff carrier with 16k miles on it on Car-Part.Com (thanks to whoever posted that on a other thread lol) and it will be here next week along with my 3.9 gears!!

Looks like I'll be dealing with the codes through UpRev. I spoke with a gentleman in New Mexico who specializes in the Z platform and has done G35 final drive swaps. He indicated to me that they were able to fix cruise control and code issues through UpRev on the G35s so he was pretty confident you'd be able to on the G37 (apparently he tells me New Mexico is around 5 years behind everyone else on tuning platforms..so no one is working on g37s out there yet?)

Probably going to hold off on the Quafie LSD for right now unless I can come up with a little extra cash before I do the install in the next couple of weeks. So I'll just deal with the VLSD for the time being.

Will keep the thread updated on my adventure with Uprev....hopefully these issues that come up are as easily fixed with UpRev as they are with EcuTek

 

I wish you well! Keep us posted on the details as they come about. Very useful info to others as it seems more and more people are understanding the cost to benefit ratio of gear swap related mods.

I highly encourage swapping out stock bushings for Whiteline ones (I think whiteline kit 0911 is the part #, plenty on ebay) when doing all this differential work. It definitely assists in making the drivetrain seem less rubbery or disconnected from driver input. Also, the stock one's (primareily the rear, subframe bushing) are prone to fail from as low as 40k miles. The oem one's are full of silicone filled sections that eventually burst and leak out the back of your diff and exhaust (so it's easy to diagnose). You probably had all intentions of doing the bushings too, but I figured I'd mention them in case others read this thread.

Kudos to you on making the big jump! ... For my '11 coupe I swapped in a '07 g35 sport differential that had 60k miles on it. All g35's in 2007 had 3.69 gearing and vlsd was of course standard on all Sport models, so it makes the search easy to find the right gears already inside the pumpkin. The key is finding one that isn't all rusted to hell from seeing winters and has a relatively lower mileage. $200 shipped from a parts yard that deals in lots of infiniti stuff, better visual condition that the stock 3.3 diff I dropped out of my car. $24 for M1 fluid, $100 for Whiteline bushings... $150 to a buddy for his expertise in leading the swap and me assisting him out in my garage.

Best. Mod. To. Date. Going 3.3 > 3.69 was just what the G with 7AT needed... and I of course yearn for 3.9 gears now! I think 3.9 is probably the best performance gear option to go for with less fear of throwing the computer in a tizzy or deviating away from stock Nissan parts ( going the Quaife route).

 

Well I have the car back...gears are in...diff swapped...and I'm at my tuner getting the speedo code cleared (it threw up a service engine soon light after about 50-60 miles...almost exactly as has been said before lol). P.S. this can be done with Uprev as well as Ecutek

No problems with ABS or anything else either.

I kept my OEM driveshaft (due to budget constraints) and just did a flange swap. May do a custom shaft down the road. This was just much easier. I never could get a handle on the specs for the DS..and putting the diff in to measure..then taking it out etc...just too much of a headache for me right now.

Just swap the flange on the diffs..put in the gears..and your off. I do HIGHLY recommend a bushing swap as was mentioned before. However I did not use whitelines. I bought SPL solid aluminum bushings (a favorite for the 370z community) and it is a noticeable difference. Also I know with the SPL bushings...they aren't going out anytime soon.

The car feels fantastic...very smooth still (that'd with my Uprev tune...I don't know how it would feel stock)...and alot more pull in each gear...your back jerks into your seat even with a light foot haha torque is now very noticeable in low gears

In case someone gets nervous from reading other threads I want to clear this up...

No there is NO vibration on acceleration after swapping the manual diff from the four bolt to the 3 finger flange. It was mentioned that because you lose the center spine of the 3 finger flange when swapping flanges on the manual differential ..the pinon extension that sticks out from the 3 finger flange...that there may be some vibration on acceleration. However the person that complained of this was boosted (600whp) which would explain the excessive vibration. So...N/A ...absolutely no problems. Boosted...you probably need to buy a custom driveshaft and keep the 4 bolt flange. After the immense amount of reasearch ive done on this mod..I believe the design of the 3 bolt flange...in my opinion..is just not for high HP builds..just won't support it. Just looking at the difference in the flanges on the actual driveshaft it makes sense.

My tires are very grippy (Michelin Pilot Sport A/S 3 ) so haven't had a problem with traction..not yet anyway lol but I'll keep updating this

And guess what...I DIDN'T LOSE MY CRUISE CONTROL

Conk also said this..that he kept his CC.. when swapping to the 3.9 gears on his 7AT...and I have a theory as to why...

The G37 vert comes with 3.9 gears...and I believe since these cars and their computers were designed to handle 3.9 gears...it doesn't interfere with the CC..

The ones I've seen that lose the CC the most are 4.08 swaps

I could be wrong..just a theory. So please take that part with a grain of salt. BUT I still have CC and other who have put in the 3.9s have kept it as well. SO it may be that the best gear swap for the 7AT is the 3.9s. Now I did use a manual diff from the same model year as my G (2013)...

As for emissions I asked my tuner and this should have no effect on the smog whatsoever. The speedo code being cleared won't be any problem.

I hope I help some people with this swap! It really is one of the best mods to do for you G. Period. Best money I have spent so far.

Any questions about my swap feel free to ask

Shout out and big thanks to conkus805, as well as, Solidus and ap0c0lypt1c for all their info...wouldn't have been able to get this done without your guys' posts!

This is the thread I used for alot of my info...

https://www.myg37.com/forums/engine-...-my-god-9.html