2007-2011 Polaris IQ Snowmobiles Service Manual, Page 315Get this manual
PVT System Back-Shifting
Back-shifting occurs when the track encounters an increased load (demand for more torque)Back-shifting is function of higher shift force within the driven clutch than within the drive clutchSeveral factors, including riding style, snowmobile application, helix angles, and vehicle gearing determine how efficient the drive system back-shiftsThe desired engine operating RPM should never fall below 200 RPM when the drive system backshifts
Driven HelixRamp
The helix cam is the primary torque feedback component within the driven clutch, regardless of driven clutch typeThe beginning angle of the helix must transmit enough torque feedback to the moveable sheave in order to pinch the drive belt while minimizing belt slipThe flatter or lower the helix angle, the more side force will be exerted on the moveable sheave, while the steeper, or higher the helix angle, the less side force will be exerted on the moveable sheave
Final Gearing