Using Automatic Transmissions

[gone7]

Does anyone have any experience simply bolting a motor to the automatic transmission?

[Frank Lee]

yes.

[oil pan 4]

Why do you want to connect an electric motor (I assume) to an auto transmission if you want the most range possible out of an electric vehicle?

[RiceCake]

Surprisingly, bolting a motor to a transmission has been common for hundreds of years now, both professionally, amateur, and commercial manufacturing do it.

I'd say it could work.

[ksa8907]

Electric motor? I assume you'd want to leave out the torque converter.

[gone7]

Good point about the torque converter. However, it is the thing that makes for a smooth start up.

@Frank Lee, what is your experience?

[MetroMPG]

This thread hereby nominated for the most ambiguous query and vaguest thread title of the month!

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Assuming you're talking about an electric motor, the thing that makes for a smooth start up is the motor controller. Wasting energy in a torque converter is not necessary. Nobody concerned with efficiency does it.

[oil pan 4]

If you want a smooth starting transmission use a clutch and flywheel on a standard transmission.

Automatic transmissions have that pesky torque converter thingy that robs power most of the time, a hydraulic pump that zaps drive power all the time and it requires electrical power all the time to operate valves on the valve body and lock the torque converter.
You can replace the power robbing torque converter with a clutch and fly wheel and replace the parasitic hydraulic pump with muscle power from your left leg. Lastly the standard transmission will only draw power for the reverse lights when in reverse.

With DC systems you can keep the clutch or go with out.

Instead of being hyper vague why dont you pitch us a concept and we can set you on a direction to go with proven systems and designs and go from there instead of starting from nothing?

[Ryland]

A guy in our local EV club has an automatic transmission in his Porsche 911, he's building a control box to make it shift so that it works properly, he said he thought about converting it to a manual but the cost would be in the $1000's and I suspect that in the end he will end up hunting down a manual transmission.

[oil pan 4]

Yeah electric motors like to spin at much higher RPMs than piston engines.

When you are stopped idealy your motor RPMs should be 0. To keep an auto transmission operating "smoothly" you will need to keep the motor around 500 or more RPMs to make transitioning between stop and go nice and smooth.

Why pick the most difficult setup possible?
Transsitioning from 0 RPMs @ 0 MPH to slow speed with an AC motor and auto transmission would be the most difficult combo I could think of.
Where a DC motor on a standard transmission with clutch and fly wheel would be smooth/easy/cheap.

It would be like my camaro many years ago before I knew how to tune the carb. At one point when the tachometer wasn't working the idle speed slowly drifted down to about 300 RPMs over time. When I was stopped and started to press the gas to go again the car would jerk forward as the torque converter hit stall speed.

If you are looking for a easy to build smooth running setup, this ain't it.