James B.

iTrader: (1)

Kyle,
A 28" tall tire rotates rotates at exactly 12.00RPM at 1mph. 88/(28*pi/12)
Top gear in a TH350 is 1:1
TH350 cannot lock the converter, so depending on stall speed there needs to be a slip margin left for the rev limit.
Using 6600RPM and 3.50 gear you could go about 157mph. (6600/12/1/3.50)

The GV gives me double overdrive. The Gear Vendors is an overdrive only, not an underdrive as their own website seems to implicate. In top gear (fourth/over) it gives me a drive line ratio of 0.59. The combination lets me have 4.56 gears in the back with 29.4" tires and still have good highway cruising capabilities. (about 2600RPM at 85mph)

I don't know about the F-Body computer code.

The TCI transmission controller is the same one GM sells through Performance Parts for hundreds more. TCI is now its actual maker, used to be SpeedPro. Price is about $660. Check it out: http://www.tciauto.com/electronics/index.htm The website doesn't make mention of it but that controller has manual mode input too so you could paddle-shift or slap-stick shift it if you want to.

NA$TY-TA

iTrader: (21)

That will be enough MPH for me....... Is there a choice for OD gears with a GV????

Sinc the (US Gear V2OD overdrive unit with a 70% O.D. gear---$1435) will work with a TH-350 it doesnt look like this swap will be so bad after all... anyone know how much HP the US gear unit will take....... since a TH-350 is a non lockup unit it will still be slipping if we add a GV overdrive or a US gear unit correct??
Thanks
Kyle

James B.

iTrader: (1)

The GV is 22% overdrive only. Because it is a planetary gear system it can be engaged or disengaged at any speed over 20mph and at any power level. It has a pump internally that is powered by the driveline which is why the controller prevents engagement below the speeds at which sufficient line pressure can be made.

U.S. Gear has options for gearing but it cannot shift under power. It can be engaged while stopped.

A converter that cannot lock will always slip. It will slip more with low rpm or high power and slip less with high rpm or low power.

taqwache

Quickin, another thing you have to remember is that if you need to finish a race in OD, then your car is not geared right to begin with. you should never use 4th gear for any thing else but just cruzing around. this is true for all OD trannys. i would say that most of those 60s and 80s that end up in the dealer for service are caused by customers towing or 4wheeling in OD. as long as your car is geared correctly and never do a WOT 3-4 shift like your suppost to, the 4L80E will last a long time.

Quickin

I have 3.73's. What would be the better gear for me than?

Maybe 3.42's or go back to stock gears (3.23's)?

taqwache

i would keep the 3.73s at first. it is really hard to tell what a car is really going to need until it is done. you can do all the math and it will sound good but it is hard to calculate other variables like exact stall slipage and tire expansion at the top end of the track. but just from experiance, with the kind of power your going to be makeing and the tranny you what, i would bet that 3.73s and a 28" tire will be perfect. after a couple of runs on that setup you will know exactly what you will need. if your converter is tight, you can probably step up to 4.10s later on. just dont ever go down on the tire diamater to gain more gear because you will need all the traction you can get.

Quickin

I don't know if you read it in my earlier posts, but I'm only interested in running from rolls. Usually from 50 to 150mph, or so. I won't be going to the track.

Mooobunnny

iTrader: (1)

Then I would recommend a T-56....

Quickin

Auto only for me. Plus, that much power will just burn up clutches all the time. The TH400 will last a long time.

2MuchRiceMakesMeSick

Does anyone know the drive terrain loss through a TH400? I know that M6s are more efficient then A4s but where does the TH400 stand?

taqwache

now that changes things. now i would say 3.23s would work real nice and you shouldnt have to go to 4th at that MPH.

ForceFed66

I know this is super dated, but you said you are running just the dimmer and not the brain. Does the Unit just require 12v to engage the OD? I picked up a used unit from the junkyard and the brain was already gone. I only intend on using it for Highway cruising so don't need the gear spilling feature. 12v to engage and disengage and that's it? Tnx

MaroonMonsterLS1

OP's last activity on this forum was 2008...I'm doubting he will be responding to you.

Call gear vendors and ask them for info.
Typically yes, it should just need an On/Off source to engage OD

for the record...I'd recommend a 4l80e long before a th400 with a GV