Rear Suspension Operation; Weight Transfer - Polaris 2003 Pro X Service Manual

REAR SUSPENSION/TRACK/TRACTION

Rear Suspension Operation

The primary function of the rear suspension is to provide a comfortable ride in all types of riding conditions. It
separates the rider from the ground, while allowing for complete vehicle control. The rear suspension also must
provide weight transfer and maintain track tension.
The rear suspension has many adjustable features for fine tuning to achieve optimum comfort. The suspension
can be adjusted to suit rider preference and deliver excellent performance for a given set of conditions. It should
be noted, however, that suspension adjustments involve a compromise or trade off. A machine set up to perform
well in the moguls would not suit the preference of a groomed trail rider.

Weight Transfer

The shifting of weight from the
skis to the track is called weight
transfer. As engine torque is ap-
plied to the drive axle the torque
is transferred to the track, pulling
it forward. This energy also tries
to pull the suspension forward.
The front torque arm reacts to
this force by pushing down on
the front of the track, in effect ap-
plying more weight to the front of
the track and reducing the
weight on the skis. It is important
to note that energy used to lift
the front of the machine is not
available to push the vehicle for-
ward.
Changing the angle of the front torque arm changes the suspension's reaction to the force. Adjusting the length
of the limiter strap will change the front torque arm angle. Shortening the strap limits the extension of the front
of the suspension; reducing the angle of the torque arm and increasing ski pressure during acceleration. Length-
ening the strap allows the front of the suspension to extend further; increasing the angle of the torque arm and
decreasing ski pressure during acceleration. Limiter strap adjustment has a great affect on weight transfer. Limit-
er straps only affect ski pressure during acceleration.
Front track shock spring preload also affects weight transfer. A stiffer spring and/or more preload on the spring
transfers more weight to the track. A softer spring and/or less preload keeps more weight on the skis. Keep your
riding application in mind when choosing springs and setting spring preload. Soft springs/preload will increase
ski pressure, but may bottom out. Stiff springs/preload will provide more track pressure (reduced ski pressure),
but may result in a less comfortable ride.
During acceleration, the rear of the suspension will compress and the IFS will extend, pivoting the machine about
the front torque arm. Because of this pivoting effect, rear spring and spring preload also have some effect on
weight transfer. Softer rear springs, or less preload, allow more weight transfer to the track and reduce ski pres-
sure. Stiffer rear springs, or increased preload, allow less weight transfer to the track and increase ski pressure.
The main function of the rear torque arm is to support the weight of the vehicle and rider, as well as to provide
enough travel to absorb bumps and jumps.
Shock valving also has an effect on weight transfer. Refer to shock tuning information in this chapter.
Scissor stops also affect weight transfer. See scissor stop information in this chapter.
7.3