An overspeed system for a vehicle is disclosed. The overspeed system may have a power source, a transmission unit, and a torque converter assembly operatively coupling the power source to the transmission unit. The overspeed system may also have a travel speed sensor configured to generate a signal indicative of a vehicle speed, and a controller in communication with the torque converter assembly and the travel speed sensor. The controller may be configured to prevent a decoupling of the torque converter assembly in response to the signal.