Clutch / Torque Converter: 200-4R Brake Switch

[345 DeSoto]

For those that have installed a GM 200-4R or 700-R4 automatic transmission in their Studebakers with NON swing pedals...What did you use for a brake switch to unlock the torque converter when applying the brakes? Part numbers, mounting procedure/location, pictures, etc.? I don't want to run the unlock through a manual switch.

[bezhawk]

https://www.bowlertransmissions.com/shop/control-modules/bowler-200-4r-lock-control-module/

I have used this kit and it works very well. It includes the brake switch.

[wittsend]

Been there, done that.

1. Just use a normally closed relay to supply the 12V+ to the lock-up wire. Hence the 12v+ power comes into and then right out of the non-activated relay supplying the current for the lock up.

2. Wire the activation coil into the brake 12V+ wiring (obviously ground the other side of the coil). You can tap the 12V+ anywhere, - at the brake switch, or with a longer wire at the brake light itself. You choose where you want to tap the power in.

When the brakes are applied the coil will energize and pull the 12V+ off the convertor causing it to unlock. The Relay is available at any electronics surplus store for about $3. Most are also dual purpose relay that can be either normally open or normally closed.

Do note that the convertor lock up is decided internal to the transmission by an internal 4th* gear pressure switch that GROUNDS the solenoid. The switch or relay you put on the 12+ side is a secondary interrupt on the positive side of the circuit. I've included a diagram I made up when I did mine. There is also an internal temperature switch in the grounding circuit that eliminates lock up when the car/transmission is cold. Since I live in So. Cal. I bypassed it after reading that it is often a failure point to the convertor NOT locking up.

My diagram also shows an indicator light. Since I went to a floor mounted shifter the column indicator was not used. I opted to use the column indicator light as a confirmation that the lock up had occurred. Because it is activated by the lock up solenoid GROUNDING I had to run a second relay that would only send 12V+ to the light once its coil grounded.

Lastly, (and it is not drawn in the circuit) I would recommend putting switch in the 12V+ line to have a means of shutting off the lock up. While not long term ideal there may be a few short term instances where not having the lock up engage would be advantageous. I have such a switch. And, so I would be aware that it might be turned off I wired in the indicator light mentioned above.

NOTE: I just looked back on the diagram. IF..., you elect to put in the 12V+ overdrive shut-off switch AND the indicator light it needs to be before BOTH relays. As it relates to the drawing it would be right after the 12V+ battery terminal. That way you turn off the overdrive solenoid AND the indicator light relay together.