Twin Cam engines make a lot of noise inside the rocker cover. This is due to the way H-D designed the rocker arm installation. The bolt that locks the rocker shaft is not a tight fit at all, when installed it allows the rocker shaft to rotate slightly forward and backwards in the housing. There it hits the rocker shaft bolt, which provides you with the unnecessary clicking sound. This kit comes with 4 precision tapered bushings that fit around the rocker shaft bolts when it is installed, which eliminates rocker shaft movement. It does not interfere with the working of the rocker arm. The kit includes a washer and nut for installation and the required tool for aligning the rocker arm shaft correctly, before the bushing is installed. An experienced mechanic should be able to get the bike back on the road in around 3 hours. Note: Compatible with aftermarket support plates. See 91-0837 for use with OEM style support plates. Note: When the rocker shafts require removal a new Rocker Locker kit will be required.