Locking an automatic in a single gear?

[bennelson]

I was browsing through Craigslist and found a Geo Metro for sale, cheap, with a title and a pretty good body.

The engine is bad, its a four cylinder with an automatic transmission.

Made me think, too bad it's an auto, otherwise it would be a perfect EV conversion.

But then, why couldn't it be? And why use it as an automatically-shifting transmission?

Is there some way to lock an automatic transmission in one particular gear? I know gear selectors usually have a Low,2nd, drive sort of a selection.

A couple summers ago, I got to drive a Solectria Force Geo Metro conversion. The body was that of an automatic transmission. I don't recall exactly what it had for a transmission in it.

What is required for an automatic transmission to run? What if it doesn't have to shift automatically? Could this be a decent EV conversion?

If not, what would be required to swap it over from automatic to a manual transmission? Do manuals and automatics have the same flywheel in them?

Just throwing some ideas out there.

-Ben

[MetroMPG]

Originally Posted by bennelson

A couple summers ago, I got to drive a Solectria Force Geo Metro conversion. The body was that of an automatic transmission. I don't recall exactly what it had for a transmission in it.

What do you mean the body was that of an automatic? You mean it was a sedan?

As far as I know, the Solectrias had a single speed custom transaxle. Don't need gears with a 12 or 14k RPM AC motor.

What is required for an automatic transmission to run?

Assuming it's old school, you just have to turn the input shaft to build up fluid pressure. More modern computerized transmissions need all kinds of sensor & ECU input to work well. (Not an issue with the Metro).

Could this be a decent EV conversion?

Auto EV's have been done. There's an automatic Metro sedan conversion under way on YouTube:

http://www.youtube.com/watch?v=OtUJW9dHW-w

Personally I don't like the idea of a conventional automatic in an EV. Even if it only costs you a 5% efficiency loss, that's too much. :P

[Coyote X]

Unplug all the connectors on the trans and I think it turns into a manual valvebody where you have to manually select a gear to drive in. I am not sure about that since the most I have done with an automatic metro is just yank the trans and toss it but I am pretty sure I read that on teamswift somewhere.

You can drive it directly without a torque converter so that gets rid of a big loss right there. The only other issue I can think of is you need the pump to be pumping all the time while rolling to keep it working so it would need a second motor to drive the pump. Not really sure how all of that could be rigged up but I am sure it is possible.

One nice thing is the way an automatic shifts gears means you can probably change gears without stopping like you would have to most of the time with a clutchless manual setup.

[Duffman]

Maybe it can be done but I think you are barking up the wrong tree.

[MetroMPG]

Originally Posted by Coyote X

One nice thing is the way an automatic shifts gears means you can probably change gears without stopping like you would have to most of the time with a clutchless manual setup.

Not really a problem, with practice. I'm up & downshifting a lot (without stopping) in the clutchless manual ForkenSwift. No bad noises either! Rev match on the downshift, use the right pressure on the shifter, and you're good to go.

[MazdaMatt]

I would think that an auto trans (old style) would be hella easier than any other option.

Just a side note - why don't you EV freaks ever talk about CSV? WAAAAY better on paper, and you're not putting down heavy torque (which is the excuse for no mass production in typical vehicles)

[bennelson]

Originally Posted by MazdaMatt

Just a side note - why don't you EV freaks ever talk about CSV?

HEY! NO ACRONYMS! EYA! (Explain your abbreviations!)

[dremd]

Typically there are 2 solenoids in a 4 speed Auto. Opening + closing the 2 solenoids select the 4 gears. Applying 12 volts to the proper solenoids will give you 1 gear. However you will have to turn the pump to make fluid pressure to hold the clutches . . . . . Wasteful . . .

Here's a link to the Gear Vs Solenoid position for the AE340
MK3 TSRM On-Line

[MazdaMatt]

Originally Posted by bennelson

HEY! NO ACRONYMS! EYA! (Explain your abbreviations!)

Haha... i'm so sorry... total brain fart on my part... i meant CVT... not CSV... ie... constantly variable transmission, as opposed to manual or auto.

[IndyIan]

Matt,
Electric motors make more torque that gas ones of similar hp and I believe most electric motors have the same efficiency almost anywhere in their rpm band. So a CVT isn't really needed for them and they are few % less efficient than a manual trans. Probably the best EV solution is not to have any transmission at all with a motor than can produce enough torque to start and enough rpm to do 60mph.
Ian