Overdrive won't kick down

[Bill OH]

I would search the Chilton’s Motor Manual on Borg-Warner overdrive. Does the overdrive drop out when the speed drops below 25mph? I know if the circuit for the governor goes to ground without the action of the governor, the overdrive will stay locked in - Starts from a dead stop in overdrive and the car will not go back. I had them in a 53 Ford and 61 Ford - great transmission.