GTM Valve Body Upgrade Review
 

I wanted to share my thoughts on the install of the GTM Valve Body upgrade for the 7AT transmission and invite comments on others who have installed the GTM VB as well.

1) As everyone knows the 7AT has had some issues with slow or lazy shifting from one gear to the next, hunting for the right gear when down or up shifting or having to mash the gas pedal to get the transmission to down shift when passing. In order to correct these issues many have resorted to getting the ECU re-flashed (I have tried this as well) with minimal results.

2) When wanting to go FI, unless something is done to firm up the shifting in an automatic transmission to prevent slipping and keeping the trans oil from overheating the auto transmission can be a ticking time bomb. Case in point: in 1998 I purchased a brand new 1999 F350 Super Duty Ford pickup with the V10. I also installed a brand new Paxton SC from Banks Engineering along with long tube headers. The SC plus the headers added about 200 HP. The transmission lasted 4 months. $7500 dollars later I had a built proof transmission that could bark the 36” tires in second gear. The truck serviced me for 13 years no problem until it was stolen. The point is that according to the repair shop that rebuilt the transmission they said that if I would have installed a shift kit and a heavy duty transmission cooler right away likely the transmission would not have had to be rebuilt. Lesson learned!

What to do for all the G37/370Z owners wanting to change the attitude of their 7AT and add some insurance to the longevity of their transmission? Get a GTM Valve Body upgrade and transmission cooler.

I contacted Sam at GTM and expressed my concerns about the 7AT and installing the twin SC kit. Sam suggested installing the reworked valve body first before installing the SC kit. Sam emailed the down load link for the re and re manual and I set to work on removing the valve body. The step by step instructions provided were very precise down to the pictures and warnings / cautions / suggestions. If you have a metric socket set, assorted screw drivers, wrench set and minimal automotive know how anyone could do this valve body re & re. I did the work myself and it was so easy. Mind you I have a hoist in my shop so that made thing much easier.

Just follow the detailed instructions, drain the oil in a clean 2 gal bucket and remove the oil pan. The instructions tell you what bolts to undo to remove the valve body and the instructions even show the different lengths of the various bolts and where they go. Unplug 2 sets of wires and you are done. About a 2 hour job.


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Follow the instructions for shipping and handling and send it off to GTM. GTM received my valve body at 2 pm on a Monday and it was ready to ship back to me the next day by 4 pm! Valve body was re-installed Friday.


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Buy a new pan gasket cost is about $40. To refill fill the transmission first calculate how much oil came out plus a few quarts extra. Buy a $13.00 hand pump from any automotive store. You will need to fabricate a fitting to screw into the refill port on the bottom of the oil pan opposite the drain plug. I did this at a cost of $12.

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Follow the directions from the GTM manual for refilling the transmission and you are done. Sam will send you a re-flash file to upload to your ECM and your car is ready to go.

As an alternative you could contact your Infiniti/Nissan shop and they could do the re & re for you. I was quoted $250. Maybe a good time to get your transmission oil flushed and changed at the same time.

Driving the car after the valve body upgrade is so much more fun. It is like driving a different car. In standard D mode going easy on the throttle you can feel the up shifting firm but not too much. You don’t want the transmission banging into gear all the time only when you need it. Stand on the throttle and get ready for some fast and firm shifting. Put the car into DS or manual mode and it feels just like a standard only a lot faster up and down and with no missed shifts. :) Another thing I noticed is when driving is DS mode and you do some fast deceleration hard on the brake pedal the transmission rev matches and downshifts so much better than before. Same thing when in DS mode and wanting to pass another car or when you want to accelerate out of a corner you don’t have to mash the pedal so hard and over rev the engine. The transmission downshifts faster and with authority. D = mode great driving. DS / M = fantastic driving.

In conclusion the car feels and drives like a sports car should. In my opinion of all the mods a person can do to the Infiniti G37/Nissan 307Z (whether going FI or not) doing the VB upgrade is right on top.

Thanks for the write-up.

Can the upgrade only be done by GTM or can they send the parts out and we have our own installer do it?

Nice review.. Thanks for taking the time :tup:

Anyone? :ugh2:

Any value to a 6MT?

No. There is not the same hardware in a 6MT.

Tim,

Thanks for posting up your review!

This is an in-house service only. For overseas customers looking to have minimal downtime, you can purchase a brand new valve body from us that we modify and send out. Then, all you do is swap valve bodies once you receive the new valve body from us.

Thanks! :tiphat:

hmmn, I really hate driving mine around in D and this seems like it may be the ticket. Especially in heavy traffic between 20-30mph it's clunky and annoying, and having to floor it to get it to downshift is annoying also which is why I drive in DS most of the time. Unless this is outrageously priced I'm liking the prospect of doing this

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Would the GTM Racelogic traction control upgrade be a worthwhile modification to work in unison with the vavle body upgrade?

Nice review :tup:

i have the built 7 AT with the race logic.
i have not had the race logic running with the 7 AT yet.
will post when i install it.

Is the core charge fully refundable if we do the "swap and send back the original after" option? Also, for HPDE / TT / Road-racey stuff (I'm probably one of the few doing that on a 7AT), does GTM have a recommended set of upgrades for the 7AT on an NA motor? The VB upgrade is on my list, do any of the other bits you sell make sense as well? Basically my power hasn't increased much, I just need the thing to be a bit more bullet-proof under track abuse and firmer/faster shifts would be nice. Mine's used almost exclusively in M-mode.

The valve body on the 370Z has a TCM that is coded specifically for the VIN that it is installed on. This renders the valve body useless to any other VIN. There are two ways around that: 1) the dealer can reflash the TCM and code it for the vehicle it is installed on. 2) a brand new valve body can be ordered directly from Nissan and coded for the VIN directly from the factory.

Therefore, for all practical purposes, there is no exchange program. That said, we are working on a solution but it is very capital intensive and not on the top of our priority list at the moment.

For a track car, there are two items I would recommend in addition to the valve body upgrade. First, if you don't already have one, is a transmission cooler. Second, a transmission fluid temperature gauge. Monitoring transmission fluid temperatures is extremely important if you are tracking the car. In fact, I would recommend a gauge with a Peak/Warn feature so you don't have to stare at the gauge while bending corners. ;)

Basically, the reason a gauge is so important is that as transmission fluid temps increase, the life of the fluid decreases dramatically. Here is an article I wrote that goes into a little more depth: http://www.gtmotorsports.com/Technic...ansmission.pdf

While that is specific to forced induction with automatics, it has some good information that does apply to what you are doing with your car.