Hey guys i'm possibly about to get serious into upgrading my 5AT tranny. I've done some searching and reading but don't have a solid understanding...

What i'd really like is if some of you guys with these upgrades can take some video of it from inside the car during WOT acceleration, particularly the rev counter.

I know what the VB upgrade does, but does it work well for downshifts too? Is there still a delay from when you push the shifter forward and it actually starts to upshift. Right now it seems to take about 500 milliseconds before it actually does anything if your WOT.

Also i'm not sure exactly what the TC upgrade will do... Can someone explain in detail?

Two things I think are probably the fault of the ECU, so maybe thats what is required to stop this annoyance... but fact you cant do a burnout and it holds your power to ~2500 RPM is a real problem for warming your tires at the drags. Also when it comes to street/track racing, particularly autocross when you need to downshift into 1st gear, you cant do it unless you are below 32 MPH, even though 1st is capable of almost 40 MPH. Downshifting to other gears will let you do it when that gear will be near redline so thats fine...

I'm hoping to get the paddle shifters James is working on here and some way to remove the shifter in the middle to clean things up, make it more Ferrari-eqsue... if thats possible, lol.

 

The burn out issue is a stock ECU thing that can be disabled with shutting down the VDC system.

The VB makes shifts crisp with greater line pressure. There is still a small delay before the shift initiates. Works Bell has a paddle shifter kit now that works with the OEM wheel. The GroundingGear grounding wire set from Gord helps alleviate this delay but doesn't work for everyone apparently. Helped me noticeably.

Picking the right TC is tough and depends on what you want to do. Maximum performance from a high stall converter may drop your ET but results in "less responsive" daily driving behavior and increased heat and lower peak power to the wheels.

If I were to do it again, I'd have stuck with the stock converter as I've never heard of one failing. I went with a high stall converter and it generates too much heat. The car is a rocket though - jumps to 3500 rpms instantly at WOT - great for getting immediate turbo spool.

 

subcribing

 

Thanks for the reply, i'm still confused about a few things though...

As for burnouts you say disabling the VDC is the trick... but I don't have VDC, just TCS and its always turned off at the track or when I want to do that. From what i've researched here the ECU would need to be reprogrammed or some system setup to trick the ECU into not knowing the brakes are being applied.

I'm still not really sure what the stall converter / torque converter does. I've even looked up info on the internet and still don't completely understand. Can you give me a practical example of what it does and what an upgraded one would do?

But your saying with an upgraded one you jump to 3500 RPM instantly when WOT? Is this at a complete stop? With brake pedal applied and WOT or just WOT off the line?

Anyway thanks for the response...

 

Me too!

 

As for doing the burnouts, I have never had any issues doing the burnouts all the way up to 6-7k(in the water box),of course with the TCS off.I have a 2003 and IIRC it has to do with the year car you have and the ECU cutting fuel so the car can't be over revved while on the brakes.Once again IIRC the fuel cutting ECU thing started at 2004.5 models,but don't quote me on that.Guys that were having the burnout issue just pulled the brake fuse and that cured the problem.Torque converters really only help drag racers so if you don't plan on drag racing don't bother.The TC does have other benefits for example when you're WOT and the car shifts the rpms won't drop as far down as they would with the OEM one.The 3500rpm example is when you WOT off the line.Remember its the heat from the TC that causes trannys to get real hot!!
My suggestion is definitely do a VB upgrade but not the TC upgrade.

 

+1 to what coach said. I have a G35 coupe with VDC so I'm not sure about the programming for TCS only Z's. I do know that there are posts on how to disable the system more definitively (as in pulling fuses, cutting wires and/or splicing in switches).

The torque converter is a fluid coupling device. It transfers power from engine to the transmission. You can change characteristics of this power transfer by changing the TC internals. I would also recommend trying the stock TC and determine if you want to change something before jumping right in for maximum performance (as there are some drawbacks as mentioned above).

I actually have my 2nd TC ready for install. This time I went for maximum efficiency rather than maximum performance. The stall was raised over stock, but not to the extent of the first one I got as part of the GTM stage 3 trans upgrade. My GTM modified TC locks close to 5k rpms on Sharif's dyno in 4th gear. THAT is a high stall converter! I have a reasonably sized transmission cooler and i had to keep letting off on the car every 20 mins at ZdayZ to keep the temps under 240. Of course those were steep inclines and declines...

 

So upgrading the TC is essentially helping you get what is similar to a launch in a manual? So say in a manual, with the type of tires and surface I wanted to launch at 4500 RPM or so I'd need a stall converter that locks up to 5000 RPM's?

So the drawbacks are overheating your trans during hard driving with lots of up/down shifting? How about for daily driving how will it affect that?

rcdash, now you say your new GTM modded TC locks near 5K RPM's in 4th on a dyno? What does this mean exactly? I'm a bit lost here...

Thanks again for the help guys

 

The first question the answer is no...there are different types of stalls,i.e. brake stall,true stall etc. Got to edgeracingconverters.com and it explains the different stalls
Upgraded TC definitely causes more heat..I have a tranny cooler w/fan and the fan kicks on quite often even during daily driving.
My upgraded TC locks up at IIRC 4800rpms

 

Well my main concern is faster shifts so the upgraded VB is probably all I need.

Does anyone know if the speed of downshifts change with the VB upgrade or does that stay the same since your not WOT when downshifting?

 

My experiences have only been with faster upshifts.

 

Cool well thats the main thing... I wonder if the shifting variables can be changed with the ECU.

Anyway thanks for the info, I gotta check around some trans shops to see if I can get someone to install the a kit.

 

Well i drove my friends Z (A.H here on the forums) and he recently got his valve body upgraded at GTM. I must say...that hting shifts very quick and hard. Its not as hard as a manual, but its still pretty firm. It chirps the 1-2 and 2-3 shifts. Downshifts seem alot crisper too. The revmatching is very quick. And of course, the upshifts are noticably quicker than stock. The response time from pulling the shifter is also improved. Its somthing id definately want..

The best part about it is that it feels like stock when youre just cruising. It is not uncomfortable in any way.

 

if youre worried about the burnout/brake thing and not about a switch, why not just wire a switch into the sensor on the brake pedal assembly, everytime you need to do a burnout with the brakes on just flip the switch so the ecu doesnt know you are making such an attempt? then you can switch it back when youre done and it will be like normal

 

how is the stillen unit.....about the same?

 

the revmatching in the 07 is much better than his 04.5. not that it was bad before, but the newer auto's have a better revmatching feature

 

Thanks for the info Aloh... what year is your friend Z with the GTM VB upgrade? As Hooper said the 07's + have improved shifting with the 5AT. I wonder if its something with the ECU or something internal to the transmission.

As for using a switch... thats probably what i'll have to do. But upgrading the ECU to a programmable one has other benefits too.

 

The stillen unit sucks.It is just a tad better then stock so i would go with sgp or gtm's v/b.I have a forged performance unit and mine is awesome(thanks Matt).

 

I have the Transgo kit installed and i can't seem to make it chirp...

 

Yes, its an 07.

How much power are you making? My friend's Z (07 HR) is making an estimated around 265-275 maybe 280? whp. (he has my stock exhaust/cats on right now, so we dont really know the exact number. He was making nearly 300whp when he had his fast intentions exhaust and test pipes on)

I think the extra power from the HR is what makes his car able to chirp.