A vibration-preventing tail wheel conversion system prevents an aircraft tail wheel from shimmying during the takeoffs and landings. The system retrofits to the original equipment tail wheel fork. A rigid insert in the form of an inverted T comprises a cylindrical base that is pressed down into the upper end of the factory fork assembly and welded therewtihin. A rigid, reduced diameter and coaxially-centered stein projects integrally upwardly from the insert base, with an annular shoulder defined therebetween. An elongated, threaded bolt rigidly penetrates the insert and extends upwardly outwardly for threadable connection to a suitable nut. A hollow, sleeve-like hub is coaxially coupled to the end of the fork assembly, externally surrounding the insert. The hub's lower, internal shoulder contacts and rests against the fork tube and the insert's annular shoulder. An upper shoulder concentrically defined by the hub receives a bearing assembly. The race portion is press-fitted within the shoulder, and the bearing is coaxially pressed against the race for rotation. A castellated nut attached to the upwardly projecting bolt compresses the bearing assembly with suitable washers to maintain the desired degree of firmness.