--- ISSUE FIXED IN POST #6 ---
I did the TransGo kit few weeks ago and now i regret it. Today i was doing 80 in 5th on the highway and floored it and this is what happened; The transmission went into Neutral and engine revved up to the maxxx. I had to put it in N to D and N to D few times to get it back into gear. I thought my trans is done at only 130k of non abusive driving.

I did clear all driveability settings in ECM and TCM so the trans can relearn itself. It shifts normal below 3-4k but it kicks so damn hard at wide open that it literally moves the rear end of my G to the side. Chirps the tires and if i'm upshifting on a slight turn, the back slips left or right depending on the curve. But the worst part of this mod is when doing 65-75 in 5th on the highway and suddenly flooring it.. First BANG, then second BANG and finally the right gear in and it goes (2-3 sec lag). It's so rough that my intake pipe holding brackets broke off and my filters now flap around.

I followed all the steps and drilled the right holes with the right bits (measured with digital caliper) so i don't know what the hell is wrong with it (besides the mod) but it really sucks..
The manual shifter is no better either, it works the same sluggish way as it did before this mod but that THUMPING and BANGING inside the trans when downshifting under full throttle is just horrible.. I've looked at few valve bodies with the same BOSCH unit but can't find the same E A plate stamp, not sure if it matters and no idea if all 2nd gen RE5R05A valve body separator plates are the same. So, if anyone knows FOR SURE and has a UNDRILLED valve body separator plate, let me know. It's stamped E A 2007 G35 5AT.

I couldn't find any info about the RE5R05A 2nd version valve bodies weather they're all the same or not (separator plate, not TCM) and i'm not sure if one from a 350Z is the same.
Also, if anyone has ever reversed the TransGo kit installation, did the drilled out separator plate work normal with the stock springs and pistons?

 

I know the transgo kit does make shifting a bit harsher, but not to that point.

u sure u did everything correctly?

 

I'm sorry I recommended that to you. I do get some of the banging you're talking about. Like the 65-75mph highway and put your foot all the way down to pass somebody. I get that one. But I guess I've learned to drive around the couple of bangs I get by being more gentle in that specific situation and figure it's still a good trade off for me because I enjoy the full throttle straight line upshifts more than I'm annoyed by the occasional bang or having to be gentle in a couple of spots. But the description of full throttle shifting while in a turn and having the back end step way out.... that sounds like driver error to me. I can't believe you want the slush box in that situation either. In that situation with a car with enough power to break the back end loose, you either need to short shift or modulate the throttle. Can't just hammer it to the floor like it's a video game and think nothing bad might happen....

I used to see reman valve bodies on rockauto for not too much money but haven't looked in years. Must be a source of used ones from scrapped cars in your area. Seems like replacement is the only option as I don't think you can undo it and it sounds like you probably did it right to me.....

Good luck!

 

Thats the reason I never did the transgo upgrade on mine. Just seems like too much abuse on the whole drivetrain.

 

I have to believe that something was not done correctly installing the mod to have the experience you had with 80 mph downshift slipping into neutral.

As to the hard shifts, I added the Z1 differential brace, the urethane differential bushing, and the subframe bushing collars. That cleans up a lot of the rear end flex when the hammer is down. You still feel the rear end torque twist when she shifts, but it isn't to the point where I feel there's a loss of control. But now that the OEM-size tires are at end-of-life, I'm moving from the 19" Rays (that prior owner ruined finish with harsh cleaner) to 18" König F1Ms, 9.5 front with 245s, 10.5 rear with 275s. I expect the rear end to feel even more planted with more beef on the back.

 

---PROBLEM SOLVED---
I've contacted TransGo 2 days ago and e-maild with Robert, and he confirmed that this mod is STRICTLY best suited for drag Boosted/Nitrous applications. So, i've asked him what can i do to reverse this operation and this is what he said; Assuming that you have kept your OEM pistons and springs during the mod install, all you have to do is remove the mod pistons and springs and reinstall the OEM pistons and springs. The drilled separator plate can stay as is and the orifice plug in the 4th hole can also remain.

So, today i got to work, took out the VB and reversed the mod. Yes, i did keep the OEM pistons and springs along with the instructions. After few hours, i got it back together and all i have to say is that this is the proper way this trans should run! The shifts are cut about 60-70% from the neck breaking THUMP to a good fast and firm shift! No grandpa slow/smooth upshift but a quick, non-neck breaking or tire chirping or *** moving shift. It's hard to describe but the best way to describe it would be between TransGo mod and stock; In my words, it's perfect for the NA platform.

So there you go, you can drive with this annoying mod or you can fix it. For those that threw away their OEM parts, you'll need a stock VB, i saw plenty on eBay as i don't think you can source the 3 pistons and 1 spring from anywhere or maybe you can. If you can, the fix is easy and before you do it, get yourself 7 quarts of Idemitsu Type S from RockAuto, they have the cheapest price on that oil.

 

The mod was done per page and checked 5 times before going back into the trans. I even watched youtube videos about this trans being rebuild, taken apart, the VB taken apart and put back together to get better idea what was ahead of me. I measured the drill bits with a digital caliper and precisely located the separator plate holes that need to be drilled, eventho the separator plate in the instruction manual is from 1st version and mine is 2nd version but the holes located matched. As for the downshifts, the only assumption i have is that the TCM registered an overpressure during downshift and dumped the solenoids to neutral for safety. I didn't go into limp mode but i'm sure it was on it's way if i didn't cycle the gears and go off the road. Either way, it's fixed now and in my opinion as a mechanic for almost 30 years, this is the way it should of been from the factory when installed in the G or Z cars.

 

Interesting that you can get half the benefit with half the installation. I probably saved my original parts but don't think I'm up for taking mine apart again (did mine on jackstands...). Maybe someday if the car doesn't just rust away to nothing on me. Glad you're happy with the outcome.

 

I did mine on Jack stands and it sucks but that's the only way for me. I spoke with Robert from TransGo and he said that the trans will probably adapt to softer shifts after this reversal but I told him that I hope it doesn't because it's really good. If it does soften up, I'll reset the TCM and enjoy.
It's really not that bad to do this, just get yourself a plastic black concrete mixing tray from Home Depot for $8 and that will keep all the trans oil in so no mess.

 

Nice to know. I agree with you. The car needs quicker shifts without chirping the tires. The abrupt shifting is the reason I didnt upgrqde my VB when I had it out.

 

I didn't experience that at all on our 07' and 08'. The shifts are nice and hard but no bangs or tire chirps. I was a little worried how they say "Race only" but was real happy after the install. The shifts get smoother the more boost you put to it too!