Transmission Question

[bigdaddycool]

No doubt i'll cop flack on this thread (just because of who I am).

Question:

Does anyone know how fast the 4 speed transmission can shift on a VZ Exec, what the actual time in mili-seconds is possible per gear?

Torque Reductions:

1st Gear - 0.5 seconds
2nd Gear - 0.5 seconds
3rd Gear - 1.2 seconds
4th Gear - 1.2 5seconds

i've reduced them to 0.4, and 1.0 but obviously haven't tuned my gears more in the gearbox to match that reduction time........ so the gears switch and the torque immediately hits alot quicker (creates a quick shift power effect) .......

Has anyone tuned their gearbox to smooth out something like this? I understand shift pressures etc, but i'm after some proper idea's.....

Ever noticed on the highway if u plant it ........ ur gearbox always takes a second or two if you put ur foot to the floor before u get take off..........

tis alot of time lost. things like the quarter mile could benift greatly from shifting faster and keeping the tranny torque reducutions to a minimum amount of time.

-=- If you have VCM Suite, I urge you guys to try this say about from 50'c+ for the transmission temp and see what you think when it shifts........ and come back and come up with idea's.

PS. The main trouble I have surrounding this question is not how to gear the gearbox to shift fast enough, it's "can I" make it shift everywhere fast enough without damaging the gearbox to allow the torque to kick back in faster.

[andyman]

the standard gearbox dosnt handle speed shift real well at all without a shift kit, its just not built that way, reducing torque management resultings in gerbox slip at high revs gear change, there is no real gain in upping the line pressure as its almost maxed out if you want better gearbox shifts youll have to get a shift kit

[bigdaddycool]

I thought you had either option............... you could either get a shift kit or just tune the gearbox......... as both do the same thing from what i've heard.

[Danoz]

Shouldnt this thread be in the tune section?!?!?!

[andyman]

I thought you had either option............... you could either get a shift kit or just tune the gearbox......... as both do the same thing from what i've heard.

no stock internals are built for comfort not for performance, if you put a shift kit in, you might notice a bit of a differance with the shifts

[impulsive]

Shouldnt this thread be in the tune section?!?!?!

does it matter? It's a VZ isnt it? Fairly intersting topic anyway!

[bigdaddycool]

yeh i dunno bout this shift kit, i think i shall investigate now.... cause i got a tuner to tune the gearbox and the shift time was dropped in half and the pressures were all adjusted. Shifts alot quicker then stock.... and i've been adjusting it over time..... but i think it's yes at it's generally as fast as it can go safely in terms of shift speeds.

If I added a shift kit i'd probably have to remove my tuned gearbox stuff....... otherwise i'd wind up with a ****load of pressure and it probably wouldn't work.

***

On a slightly different topic, is there some kind of formula to work out my 'rpm vs speed vs diff ratio'.

eg. under WOT in Performance Shift I want to shift out at say 6200 to 6400 rpm on my 3.45lsd, but I need to match the RPM and speed for it to work properly otherwise u get a bit of a pause when u shift if the RPM and the speed doesn't match.

so I want to find out what speed I can shift out at 6400 in 1st, 2nd & 3rd in terms of km/h. I can measure this with VCM Suite driving but it'd be easier to have a forumula of some sort.

[Torquative]

no stock internals are built for comfort not for performance, if you put a shift kit in, you might notice a bit of a differance with the shifts

PFFT UMM yeh you'll notice a mega difference, if violent shifts and grinding banging noises at low speed (peak hour) is what your after.

Ive learnt my lesson, dont f*ck with the gearbox

[bigdaddycool]

yeh i dont trust the shift kits as it's a rather mechanical thing (changing hardware stuff) ........

tuning the gearbox i think is safer.

[andyman]

yeh i dont trust the shift kits as it's a rather mechanical thing (changing hardware stuff) ........

tuning the gearbox i think is safer.

ill say it again, if you want performance get a shift kit, as matt pointed out if you want comfort and driveability dont shift kit and put up with it

[delcowizzid]

yip add a shiftlit so it has way more fluid flow and more circulation for cooling then tweak the pressures youll gain way more the valvebody and seperator plate can only flow so much and adjusting it in the tune wont do anything when the holes are too small for enough flow

[bigdaddycool]

meh. my car shifts good in my opinion from the changes i've done........... i just thought the shift kit was the same thing as tuning the gearbox, but just a mechanical way of doing it without adjusting things.

but yeh, if it helps the tranny cool more thats always good, i got a tranny cooler...... as everyone knows, heat kills everything so....... yeh