I am running Godot 3.1.dev (windows, built from source on github). It seems that 3d physics hinge joint only support positive values for the motor velocity through the inspector. To reverse motor direction I am having to rotate the joint y: +/- 180 degrees. Not really the way I want to do it.
I will add PD control to the joint which will want to change the sign of the velocity of the motor and so flipping the hinge joint orientation is not really an option for me.
Is this a limitation in the inspector or in bullet itself?