An injection molding apparatus having a valve pin plate coupling at least one valve pin to an actuator which, in operation, axially moves the valve pin plate between a closed position and an open position. The valve pin is coupled to the valve pin plate via a valve pin coupler. A biasing member is compressed against a support surface by the valve pin holder when the valve pin plate is in the closed position to create a supplementary coupling force coupling the valve pin to the valve pin holder.