Failed crank hubs have been a common ailment of the N54 / N55 / S55 family for the last 15 years, leading to crankshaft spin, causing skipped timing and potentially catastrophic engine damage.The VAC Motorsports 4 Pin Crank Hub is more exact than OEM due to precise engineering and careful CNC machining. The 4 pin design prevents the valve timing and oil pump chains from spinning independently, and mechanically securing the crank hub to the crank nose. Doing so keeps the entire assembly accurate and secure.Via careful engineering and design, VAC was able to minimize the total assembly from three pieces to two by combining the hub and timing sprocket into a single machined unit. So long as the bolt is properly tightened to the crank, the timing sprocket will always be in sync with the crank.Kit Includes:1-piece crank hub/timing gearKeyed oil pump gearGenuine BMW crankshaft boltDrill bitDrill guideVAC Crank Seal GuardFailed crank hubs have been a common ailment of the N54 / N55 / S55 family for the last 15 years, leading to crankshaft spin, causing skipped timing and potentially catastrophic engine damage.The VAC Motorsports 4 Pin Crank Hub is more exact than OEM due to precise engineering and careful CNC machining. The 4 pin design prevents the valve timing and oil pump chains from spinning independently, and mechanically securing the crank hub to the crank nose. Doing so keeps the entire assembly accurate and secure.Via careful engineering and design, VAC was able to minimize the total assembly from three pieces to two by combining the hub and timing sprocket into a single machined unit. So long as the bolt is properly tightened to the crank, the timing sprocket will always be in sync with the crank.Kit Includes:1-piece crank hub/timing gearKeyed oil pump gearGenuine BMW crankshaft boltDrill bit Drill guideVAC Crank Seal Guard