Polaris 2001 High-Performance Snowmobile Service Manual (PN 9916690), Page 295Get this manual
REAR SUSPENSIONTRACKTRACTION Shock Valving
The valving piston has six large compression holes and three smaller rebound holesThe smallest hole, called the low speed hole, controls low speed rebound dampingIt also has about 25 effect on low speed compressionThis hole is usually between .050 and .100 in diameterYou can drill the piston with numbered drill bits to get any size you wantBlank pistons are also availableThe rest of the valving is controlled by the valving washersThese washers are available in various thicknesses and diameters to achieve the proper amount of stiffnessFollowing is an example of available valving washer sizesWasher Diameters .700 .800 .900 1.000 1.100 1.250 1.300 1.450 1.600 Washer Thicknesses .006 .008 .010 .012 .015 Use thicker, larger diameter washers to make the shock stifferThe rebound stack must start out with washer that is at least 1.250 in diameterThe compression stack must start out with washer that is 1.300 in diameterAt slower shaft speeds, only the washers closest to the piston will bend and allow oil throughAt fast shaft speeds the washers bend further, so the washers further from the piston are helping control the oil flowIn summary, the washers closest to the piston control low speed valving, and the washers furthest away affect high speed valvingIn the rebound stack, the washer next to the piston is more medium speed valve because of the oil flowing through the low speed holeIt takes lot of time and practice to see which valves control the way your suspension feelsSometimes it's good to make big change to see how the shock will react, and then end up somewhere in betweenNOTE: For every of travel limiter spacers added to the shock, decrease the IFP depth by .115NOTE: For every .25 of travel limiter spacers added to the shock, decrease the IFP depth by .029Compression holes Rebound holes Piston