Wind turbine gearboxes are subjected to fluctuating torque conditions, which may generate vibration problems. This paper analyzes the mesh displacement of a helical gear pair, inspired by the challenges posed in simulating the high-speed stage of the wind turbine gearbox. The detailed mesh model, considering static transmission error, time-varying mesh stiffness, and backlash, associated with a 12-degree-of-freedom gear pair model better represents this system. The model also takes into account a load torque factor to prevent over-speed conditions. Results show a comparison between the system’s response in the absence of backlash and when backlash is introduced. When there is no backlash, both the driving and driven gears exhibit quasi-periodic behavior. When there is a backlash, single-sided impacts occur along the permanent response of the gear system, a severe vibration condition that may cause damage to the system.