adding washers will increase belt height and tension. that how you adjust it, by adding or removing washers. measure the distance between the sheaves now and calculate what you need for washers. oem washers are available in 1mm and .5mm thicknesses. the sheaves should be 35-35.8mm apart, depending on sled model. i would not use lock washers! if you want to go cheap, take your calipers to the hardware store and match the washers your buying to make sure all three are the same thickness to maintain some sort of balance on your clutch. or buy oem if they have them in stock.