YBR125 motorcycle gearbox auxiliary shaft assembly, shaft length 160MM, number of gear teeth (37T/23T/25T/32T/21T) and the original car gearbox is completely matched, direct replacement without adjusting gear engagement clearance; Equipped with driven gears of various gears, one-stop replacement of transmission power output shaft, no need to purchase gears separately; The gear tooth surface is quenched, resistant to wear and damage, to ensure smooth meshing and long-term use stability when shifting gears; The size error of the journal is very small, and the bearing/bushing is closely fitted, and the operation is not loose or abnormal. After replacing the old auxiliary shaft, it can be used with the adjustment gear gap of the main shaft, and the adaptability is strong.