R10 Overdrive 6 volts solenoid on 12 volts.

[Francois Pelletier]

Hi guys,

 

I have installes a R10 overdrive transmission on my 12v converted 1940 Dodge sedan.

The transmission came with a 6 volts solenoid.

I decided I would not use any of the auto actuation system and use a simple switch and relay.

You can't just put a resistor in series because it actually is a dual coil with a much stronger one pushing the pin in and then a lighter one holding it in.

But you can seperate the 2 coils and feed them separately. The big one through a 0.3 ohm resistor and the small one a 3.0 ohm one.

The wires a easy to access and split. There is a ground switch tab wich is not used when going for manual actuation that can be used for the small coil wire.

 

I have about a 1000 miles done with it and love it !! Only problem is that I used a small wattage resistor for the big coil and when the swtch is left on while the overdrive cannot engage, it overheats and smell... It could easily be corrected with a higher wattage resistor. 

 

Pictures of the modification to the solenoid, required resistors and actuation switch wich is a motorcycle flasher switch. :