As many of you are aware, the Jatco RE7R01A 7AT transmission in our cars is widely believed to encounter limited lifespan issues within FI applications. Companies like Level 10 and IPT build performance upgrades/builds for our version of the transmission, but for me personally, there are not enough reviews and discussions out there to justify the expense/risk, which can often exceed 5K if you purchase a full rebuilt unit from them: https://www.levelten.com/product_p/infin-g1800-re7.htm

So I begin to think more about other options, one of which is a 6MT conversion, and another seems alot more attainable and is actually fairly tried and proven.

Recall that Jatco makes our transmission in two versions, the JR710E and JR711E. According to sources online, our "710" model is rated for 425 ft-lbs. of torque while it's cousin in the , and the "711" in ALL 2016 and newer Qs (Red Sport has the same trannie as the base Q) is rated for 600 ft-lbs., which is significant.

I initially came across this blog from Soho and checked out some of the packages listed, which seemed reasonable: https://sohomotorsports.com/blogs/ne...z-infiniti-g37

I then decided to call these guys in NC and was pleasantly surprised at how well versed (and enthusiastic) they are on the JR710E (VHR) vs JR711E (VR30) topic; It was a red pill moment for me as I always assumed there were some slight differences in the two, but apparently the differences are substantial.

Here's a list of things I learned that caught my attention.

• Recall that they also build SC and TTs as well, and I was told that they have customers that are pushing dyno numbers close to 700HP using the 711 7AT.
• They confirmed that the larger torque converter and clutches (more and stronger) on the new VR30 trans are superior
• At the 10 year mark, they see alot of our 710 transmissions fail based on TCM/Output speed sensor (P0720)/Torque Converter failures, or failures within the trans fluid cooling system which is shared with engine coolant on our cars.
  • Apparently, it's common for the shared radiator to fail and allow engine coolant to leak into the transmission.
    • At a minimum, they recommend bypassing this setup and installing a separate cooling system for the transmission (Stillen, Soho, Z1 and others make one for our cars)
• When upgrading the VHQ trans to one from a VR30, you can keep the OEM flexplate if there are no plans for FI. If you do plan to run FI, then upgrade the OEM flexplate (with new HW as the performance plates are thicker than OEM) as they have been know to crack.
• They recommend a new valve body and TCM when upgrading to the VR30 transmission as they feel the OEM unit is good for about 10 years. Not sure on this aspect as it adds substantial cost per the quote below.
• A tune is also needed. Note here that they said the VR30 transmission will work in our cars without a tune, but the difference with a tune is night and day and the shifts are so much better that many of their NA VHR customers upgrade their transmissions and immediately see improved quarter mile and 0-60 times.

They actually build a full kit that can ship directly to you (add 1K shipping cost to below for me in CA), which is outlined below in the quote they put together for me. Note that this quote is for a RWD Sedan, but they build Coupe RWD, Coupe AWD, Sedan AWD kits as well. In looking at the quote, I would likely source the transmission through my long time mechanic and try to find one in the 20K mile range and avoid the need for a new valve body/TCM and minimize shipping costs, then buy the rest of the kit from Soho.



Anyways, it was a pleasure talking to Justin from their team as he was really knowledgeable on the platform and was able to articulate the advantages of the upgrade with relative ease.

 

The only question I have- and a few others as well- that no one either knows the definitive answer to nor cares to bother investigating or elaborating- involves the small number of us that have the 5AT (RE5R05x) tranny:

Is the 7AT- any version- backwards compatible with non-native 7AT G's? Seems the only option for us 5AT folks is the Transgo kit which, ok, but does not address potential solenoid/ valvebody/ clutch pack/ etc. failures.

While it is generally considered that the 5AT is more reliable, stout and less prone to "issues" than the 7AT's, no AT will live forever... and it seems that there are no options for these cars short of finding a "good" junkyard replacement or swapping to 6MT which, for most, is not a feasible route. Thankfully, not a concern for me a the moment but options would be nice. After driving with the DCT in the BMW I wish that was a option...

Maybe these folks will know the answer. ¯\_(ツ)_/¯

 

I owned a G35S prior to my G37S and agree that the 5AT was very responsive and generally accepted as very reliable in the first gen; the Transgo kit was essentially thought of as a must have, but more as a means to improve shift points and stall speed (the way tunes are today); I never installed one because I thought the transmission worked well stock.

Note that the 7AT was thought of as very reliable in the beginning as well, and it wasn't until people started installing the Stillen SC that we saw complaints related to the 7AT not being able to handle more than 400 ft-lbs of torque; To this day, I am not sure who came up with the number, but yes, going from 280WHP to 400WHP overnight will likely cause issues. Also, I have spoken to several long time transmission shops here in SoCal and they feel that the best transmissions Jatco has ever made are in our cars. No complaints from their customers and hundreds of thousands of miles should be expected.

What's confusing is that I see alot of posts here and on the Reddit sub and it seems that there are far more TCM/Speed Sensor failures reported on the VR30 transmission than the 7AT in the G. I've always thought this is due to FI and ability to install a boost controller and sudden increase HP/TQ by 20% with the flip of a switch. Then I speak to Soho and they tell me the VR30 trans is clearly superior. Head spins.

Regarding my comment above related to FI and reliability, I think this is also why the 5AT was more reliable as the G35 NA platform like the G37 was very limited as far as mods went, so there was plenty of margin built in; Note that Level 10 has experience with the RE5R05: https://www.levelten.com/category_s/37.htm

Update: I spoke with John at IPT transmissions this afternoon.

He said that the VR30 transmission is indeed a little stronger than the VHR unit as Nissan has not only increased the number of clutches in each clutch pack, but also addressed some of the shortcomings with the torque converter and made small modifications to the valve body materials as well. He noted that the clutch packs on both (and the 5AT) are the same, but there are more clutches in each pack in the VR30 trans.

All of these items are addressed in the performance upgrades they offer for the 5/7AT: https://www.importperformancetrans.c..._detail&p=5437

Note that they started off with the RE7R05A, so most of these upgrade items apply to both transmissions:

1.
Rebuilt 2 disc torque converter (vs. 3 disc in the VR30?)
https://www.importperformancetrans.com/index.php
Note: Watch the short video on this paging showing the inherent flaw with older Jatco torque converters.

2.
Upgraded Valve Body
https://www.importperformancetrans.com/index.php

3.
Rebuild kit
5AT: https://www.importperformancetrans.com/index.php
7AT: They require that you send them the transmission for the rebuild, which is right around 5K. Here, I was thinking it would make more sense to source another trans, have them build it, then sell the old trans from the car, but he said they prefer to rebuild the unit from the car to avoid ECM programming issues.

Anyway, food for thought. Sounds like the torque converter and valve body upgrades would be a good start. John believes that the TCMs (transmission computers) in our cars fail due to the fact that they are inside the transmission and exposed to large amounts of heat. He said that on other models where they are external and located say under the dash, failure is not as frequent.

Good discussion.