2006-2008 Polaris Snowmobiles FS/FST Service Manual., Page 241Get this manual
Rear Suspension IQ 121 Heavy Torsion Spring Installation
Please reference the following information when installing heavy torsion springs on IQ sledsThe issue that arises when installing the heavy spring on Fusion sled is that the coil stack of the torsion spring is wide enough to interfere with the suspension arm clamp nutTo work around this issue you will need to order two (one for each side) of the following partsRelocate the two washers that are next to the clamp nut to the outside of the link arm