Thunder Products TRA Belt Adjuster Kit: This kit allows you to space the sheaves of the Ski-doo TRA Primary sheaves closer together for optimum belt to sheave clearance. An ideal number is .010" to .015" and that keeps the Clutch system working efficiently and starting out in a good ratio. The more belt side clearance the more the sheaves have to close to squeeze the belt and the higher the belt must ride in the sheaves before they grab. Most factory Ski-doo clutches are .080-.090" clearance and the more your belt wears the worse this gets. This kit installs easily with TRA service tools and multiple thickness spacers and washers allow you to set the clearance to multiple positions. The engagement will be smoother and more direct with lower rpm and results in cooler more efficient belt and sheave temperatures. This kit should be in every Ski-doo TRA clutch.