I am planning my next Courier-based project, and want essentially a two speed electrically shifted transmission with reverse. For this, I am looking at using a Chrysler A604 since it's completely solenoid controlled. I don't need the torque converter, so there will be much less heat buildup and less fluid flow needed. I plan on eliminating the engine driven pump completely since the motor will be stopped when the vehicle is stopped, and use an electric pump to supply fluid pressure to the trans. The problem I am having is flow rate vs pressure. The trans test pressures are upwards of 140psi, but running less power into it I should be ok with 80-100psi tops. However, the flow rate required is a mystery and really effects the cost of the pump.

Running just the clutches, what kind of flow rate would I need?

 

I don't know that anyone knows. Most of the flow rate in an automatic feeds the torque converter. The clutches need minimal flow except when filling, but they don't take much fluid to fill, either. It's a high flow rate for much less than one second.

I'm guessing, and I stress guessing, that the trans stock used 1-3 gallons per minute. You will not need that much without the converter, but how much less I do not know.

 

I guess you can't get your hands on a 2-speed Lenco with air shifters? That would be kind of cool to have.

 

Well, I'm trying to minimize loss in the drivetrain, and the most efficient hypoid gear setups take 10-15% of the power delivered just to make that 90* turn. The A604 is commonly found in Caravans, and while it has a bad rep for failure most of that is due to people spinning the tires and the diff pin gets launched. I have seen this so bad it jammed the pin into the torque converter and locked it. There is a simple fix for the older transmissions, and the later model ones don't have this issue.
This is going to be an electric drive, with fairly tall gearing so it can cruise at a moderate power level, and a selectable low gear for taking off without having to floor it. By cutting away the upper part of the bellhousing, I can fit this trans under the bed floor on the Courier keeping the bed intact. Then a bunch of lithium-ion batteries up front, some more under the front of the bed, and I'm looking at a 200mile range electric pickup.

I didn't realize the trans used that little fluid, I thought it would be around 10gpm. I want to use an electric diesel pump for the main trans pump, so if it is really only around 1gpm that would save quite a bit. Another option though would be a small hydraulic pump run off the electric drive motor and an accumulator on the trans with automatic fill and a manual release. Pressurize the accumulator by driving, then just before taking off trigger the release so the motor can spin up smoothly instead of spinning up and then the clutches engaging suddenly.