TOdoubleD

Hi everyone, this will be my first official thread post since being a new member. I've been coming on here for years and reading a lot of good info to help with my Z build so first off I would like to say thank you to everyone who have spent so much time contributing to helping others with their questions and personal builds.

So here it goes. I have an 04 350z 5AT. I'm building it for track use, but it is also currently my daily. I have run a couple track events so far at Streets at Willow Springs and Chuckwalla Raceway. If you go to my profile you can see the list of mods I have so far.

My next upgrade I would like to do, especially after this last track day, is a valve body upgrade. During sessions, I was having trouble downshifting quickly between gears. Usually 4th to 3rd was fine but if I wanted to go to 4th to 3rd to 2nd quickly, there would be a delay and would have to brake more to drop the rpms before it would allow me to shift to 2nd.

First, I'm wondering if a valve body upgrade will solve this issue with the delayed downshift? I keep reading how crisp the shifts are from 1st-2nd, 2nd-3rd, and 3rd-4th with that person's new VB upgrade. But what I am not seeing a lot of is downshifting. I guess it doesn't really matter to a lot of 5AT Z guys since a lot of them aren't trying to track their cars very often and is meant more for street racing, drag racing, canyon driving, etc. But I'm trying to build a competitive track car and I don't want to constantly be checking my gauges before going into a corner to make sure I'm in the proper gear. I basically want the car to downshift just as crisp as it upshifts with the VB upgrade. And also if the VB upgrade is not the answer, does anyone have any other solutions?

Please leave the flaming out of this thread. I know I have an automatic and I can't do the same things that others can with a manual. I've accepted this fact, but trust me it's not because I can't drive a stick, it's because this car and I have a special history so I decided to keep it. And no, I'm not going to do a manual swap so please leave those kind of comments out of this thread. Thank you.

So by performing the VB upgrade, will this solve my downshifting issue? I was also told that I possibly would need a rev limiter to compliment the VB upgrade to really solve the problem.

Lastly, regarding which VB upgrade to go with. Is there a better quality shop to do this. Stillen or GTM? What are the differences in workmanship, time to complete, etc. Thanks again guys and sorry wasn't expecting this thread to be this long.

350Zdj

iTrader: (3)

Unfortunately the downshift lag remains the same.
Transgo only helps upshifts and not the downshifts. I believe it's the same for the other VB kits in the market. Getting the AT to downshift where you want it can very frustrating, especially during autoX runs. It takes away your concentration too.

If you search the forums you will find out that Stillen VB upgrade isn't that effective. GTM has been getting so many bad reviews recently. Buy the Transgo kit and take it to any shop that you trust.

If you see your Z doing more track days in the future, I suggest you get a manual instead. I got an auto Z and I'm just saving up for a manual trans swap.

TOdoubleD

Dammit. I live in Vegas and not sure of any performance trans shops that would take on this task. I'm a senior parts consultant at Nissan so I might just have my master tech do it. I'm wondering if it's even worth it now. My times definitely suffered due to the downshift lag. I don't autox but on the track I don't wanna go to hard into a corner because I can't downshift into the correct gear I need. Now I'm not sure what to do.

Thank you for the response. Guess Stillen or GTM aren't the way to go. I keep hearing SGP getting thrown around. Are they still in business or was that just a short-term thing back when these first came out?

I guess I may just have to bite the bullet and do a manual swap :/

350Zdj

iTrader: (3)

I'm not sure how much work have you done to your car. If you are just starting to mod it, just trade it off for an MT Z. IMO that's the best, most cost-effective way.

Re: Transgo install, search the forum you will find the DIY procedure. The kit also comes with a manual instruction. I'm sure any experienced mechanic can do it.

Btw, I have also re-built my AT trans due to worn clutch packs. It's not fun looking at those bills. lol. Install oil cooler for your AT if you are planning to go ahead with this project.

terrasmak

iTrader: (8)

What Nissan dealer? I know a master tech in Vegas with his own shop

samsniss350z

I agree with 350Zdj's advice and seriously consider replacing your AT with a MT. This is not because I think that AT boxes are Barbie boxes but the simple fact that they're not really built for what you want to use the car for. You have no real control of downshifts whatever mods you do. The closest you could get would be 370 with a semi-auto box. But that depends heavily on budget. Seriously, start checking out manuals.

shadow191

iTrader: (1)

I had the Stillen VB in my FX; upshifts were much better, maybe not as good as Transgo, but it would shift pretty hard. Comparable to VB upgrades in previous cars. But downshift lag was still there since that's not really a line pressure issue. It would require TCM reprogramming to fix which isn't really available that I'm aware of.

TOdoubleD

@350ZDJ I just put almost about $10k in my car between suspension, brakes, intake/engine dress-up, exhaust, and wheels/tires so trading in isn't an option plus I'm about 4-5k back in book on trade value.

@terrasmak I work at Autonation, but I've been a parts guy at Henderson and United. I've worked with and known the master tech you are referring to though. He just bought a GTR.

@samsniss350z I agree with you that what this tranny is built for and what I'm trying to do isn't what it's made for.

Thanks for all the advice guys. I think I'm gonna have to start lookin into doing a manual swap if I'm gonna be serious about tracking this thing.

350Zdj

iTrader: (3)

Uprev software has the ability to adjust the TCM I think. They have not openly announced this capability yet for some reason I don't know. I've seen a discussion about this in this forum.

LMAO we're in the same boat.

Good luck man!

There's a fully documented step by step AT to MT conversion project in here. A must read!!!

edit: here
https://my350z.com/forum/engine-driv...de-thread.html

TOdoubleD

Just tried reading a couple thread topics and it doesn't look like the TCM can be tweaked with at all.

@350zdj Thanks for the project thread. Definitely gonna have to read up. And ya trading it in is NOT an option lol

myfirstzcar

I know the tcm can be manipulated, I just can't remember who offers it....I read that on the Titan forum.

Jaxter

iTrader: (3)

I got a Transgo, transmission cooler w/gauge, and Uprev's Trans tuning all done by JTran. It made the car a lot more fun and responsive. I've never tried the high-speed downshifting though. The gauge is very useful. Our transmissions get hot quick.

TOdoubleD

Does anybody have any recommendations for a performance clutch and lightweight flywheel but something for a beginner that will have a little give in it? Haven't driven a stick in years since I was a porter so I'm gonna be a little rusty

RudeG_v2.0

iTrader: (1)

The valvebody upgrade is great for drag racing, but unfortunately doesn't resolve the down shift lag in manual mode for the road race and autocross guys. If you do decide to keep the 5AT, go with the TransGo valvebody upgrade. It's the best and most proven IMO. SGP is out of business and scammed customers (including me) on 5AT builds before they went out of business. iStan referred me to a Nissan master tech in the Las Vegas area who rebuilt my trans the second time. IIRC his name is Chris. I don't know if this is the same guy who terrasmak is referring to.
The JWT clutch and flywheel combo is very popular and streetable.

myfirstzcar

Try googling a company called Level ten, they'll tell you what it takes, if it's possible at all.

RudeG_v2.0

iTrader: (1)

LOL Level 10 is crap. Try Googling their reviews.

IPT is superior to Level 10.

http://www.importperformancetrans.com/nissanre5.shtml

However, shipping out to IPT would be completely unnecessary since there is a good proven Nissan trans builder in the Vegas area local to the OP.

myfirstzcar

Ever had one built by either company?

RudeG_v2.0

iTrader: (1)

No, but I did a lot of research and knew to stay the hell away from Level 10.

https://my350z.com/forum/engine-and-...mendation.html

https://my350z.com/forum/forced-indu...y-level10.html

They have a crap reputation with the Supra guys too.

On the other hand, IPT has a much better reputation.

myfirstzcar

That's funny, I have yet to see Titan member complain about anything that level 10 has done, although they probably have.

Let's keep in mind that the quickest N/A Titan is currently into the 12 second range at 5000+ lbs.

Nobody's perfect, and I'm sure if you look around you'll find just as many horror stories about IPT.....But I don't have all night to dig stuff up either.

TOdoubleD

I appreciate the references guys, but I think I'm just gonna do the manual swap and upgrade to an OS Giken LSD and 4.08 gears while I'm at it. Still have to research on the right clutch/flywheel setup for my beginner skillset before I can get good enough to take her back on the track