Jims Mainshafts

4 products — part of all Mainshafts

Jims mainshafts for Harley-Davidson cover the primary output shafts within the gearbox that transfer power from the transmission to the final drive. The mainshaft is a high-stress precision component — it runs in needle bearings inside the gearbox case and carries the full torque load of the V-twin through every gear ratio. A worn or damaged mainshaft introduces gear engagement problems, excessive bearing noise and output shaft runout that affects belt or chain alignment and longevity. Jims machines their Harley-Davidson mainshafts to the tight diameter tolerances and surface hardness specifications needed for correct bearing fit and long service life, making them the standard choice for both OEM-replacement and performance Big Twin transmission rebuilds. Iron City Motorcycles, your authorised Harley-Davidson dealer in Leeds, stocks Jims mainshafts. Browse the full Jims Mainshafts range below.