# [EVDL] GM-TH400 transmission project



## EVDL List (Jul 27, 2007)

Hello Chris,

I have contacted Gear Venders about there over and under drives. These are 
design to use after the transmission which must be up at least 500 rpm for 
them to work. I wanted something, that I can start to move the EV right 
from the start like a manual transmission.

The TH-400 unit was built by tci.com and does not use a torque converter 
and uses external transmission pump that will pre-pressure the transmission 
oil.

There is no automatic shifting in this transmission. They remove the 
governors and kick down shifting unit and has a full manual valve body in 
it.

It weighs 60 lbs less than the manual I have now, not counting the flywheel 
wheel, pressure plate and clutch weight.

According to the mechanics, it will last over 100 to one over standard auto 
transmission for my type of driving.

It also uses a modulator value that is operated by the accelerator linkage 
which proportion increase and decrease the vacuum signal to the transmission 
modulator. As the hg.in. of vacuum drops which may indicated more load, the 
transmission pressure is increase. As the vacuum rises or at cruising speed 
will the accelerator is at a constant position then the transmission oil 
pressure drops.

Normally when this transmission is use for drag racing, you turn on a 
modulator control switch that shuts off the modulator to O in.hg. which 
gives full oil pressure for the run, which may or may not blow the seals at 
a constant high oil pressure.

B&M has a electrical operated modulator, that I may be looking at and 
testing.

This motor and transmission is a spare or standby unit that will be use to 
replace the existing drive which will be put in maintenance the next or the 
year after.

The first gear overall ratio will be 15.3175:1 which will allow be to go up 
and above 30 mph without shifting. I had to shift the manual transmission 
with 19.496:1 ratio which I had to start to shift to 2nd gear 25 mph which 
than drop the gear ratio to 13.925:1 which cause a 20% increase of motor 
ampere in this gear.

I also contacted Linco Transmission Systems, but also these transmission 
module's need a starting 500 rpm to start working to lock up these 
transmissions and the gear ratios are not deep enough.

Roland






----- Original Message ----- 
From: "Chris Stephens" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Monday, February 09, 2009 5:27 PM
Subject: [EVDL] GM-TH400 transmission project


>
> Roland,
>
> I notice you posts about this once in a while. The manual shift TH-400
> sounds like an awesome idea but complicated. How close are you to actually
> trying it in an EV?
>
> With this much thought and time in this, I'm sure you considered
> alternatives like GearVenders overdrive or other options for rock crawlers
> and such. Why did you rule them out?
>
> I think I'm going back to my original idea before I joined this list. My
> plan was to use a transverse front wheel drive transmission turned 
> sideways
> and an AC motor. The transmissions original left drive shaft will go to a
> front differential, and right driveshaft output to a rear differential
> giving me AWD. Keep the original front wheel drive open diff in place and 
> it
> should act now a center diff for front to rear. I'm also thinking about
> converting it to a straight cut gear crash-box. It will be a little noisy,
> but will shift easier-faster without having to wait on synchronizers to
> catch up.
>
>
> Stub
>
>


> > Roland Wiench wrote:
> > > I have tested this out selecting the P on a TH-400 super heavy duty
> > > automatic that was converted to manual shifting only.
> >
> ...


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## EVDL List (Jul 27, 2007)

> Roland Wiench wrote:
> 
> > Hello Chris,
> >
> ...


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## EVDL List (Jul 27, 2007)

Hello Jon,

The Powerglide has only one speed reduction gear that is a aftermarket gear 
set at 1.76:1. This would only give me a overall ratio of 9.8:1 which would 
be like starting out in third gear with my existing transmission.

I try pulling out from a dead stop in third gear and the ampere would start 
to go over 600 amps. At 25 mph town driving, the motor ampere is at 250 
amps while the battery is at 175 amps.

In 1st gear starting out at 15.3175:1, I can hold the motor ampere at 200 
amps and battery amps at 75 amps while I accelerator from 0 to 25 mph and 
still go up to 35 mph in the first gear for much of my driving.

I was thinking of having the new 4.01:1 first gear put in, but this would be 
way too much overall ratio of 22.33:1 which would be about 20 mph top speed. 
It would work if the differential gear was a 3.90:1 which would give a 
15.639:1 overall ratio.

Roland


----- Original Message ----- 
From: "Jon Bishop" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Tuesday, February 10, 2009 6:51 AM
Subject: Re: [EVDL] GM-TH400 transmission project

> They are also extremely expensive for 2 gears... I feel a powerglide
> would be a better investment, if 2 gears is all you are looking for.
>
> > <snip description of TH400 racing trans>
>
> I would be really interesting in hearing how this works out for you.


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## EVDL List (Jul 27, 2007)

be sure and ask How heavy his car is to understand why he needs so much gear
....a lite car could get away with less.
R



> Roland Wiench <[email protected]> wrote:
> 
> > Hello Jon,
> >
> ...


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