Rear Suspension Tuning; Shock Tuning; Rebuildable Shocks - Polaris 2003 Pro X Service Manual

Rear Suspension Tuning

Many factors influence the overall handling characteristics of snowmobile suspensions. Rider weight, riding style,
course conditions, and the condition of suspension components are some of the things that you have to consider
when tuning a suspension.
On new machines, or whenever new suspension parts are installed, the sled should be ridden for at least one
tank of fuel to allow moving parts in the shocks and suspension to wear in.
S
Front Suspension: The front suspension should sag (unloaded) about 1 (measured at the front bumper)
with the weight of the sled. Use stiffer or softer springs as needed to keep from bottoming too hard, and to ensure
the entire range of travel is used. HINT: Sliding the jounce bumper all the way down the shock rod will show how
much travel is being used.
Rear Suspension Tuning
To begin suspension tuning, check the condition of shocks and other suspension parts.
S Inspect and grease all suspension parts, making sure they pivot freely. All suspension components should
be greased prior to adjusting the suspension. Regular maintenance greasing should be done with no weight on
the component to allow grease to reach important contact areas.
S
Loaded Sag: Set the preload on the rear springs for the correct sag. There should be 1 1/2 of sag on the
rear suspension when the rider on the snowmobile, measured at the rear bumper (4 at rear of tunnel edge on
Edge models). Bounce on the suspension a couple of times to overcome any "suction" and settle the sled to an
accurate reference point. The rider should have their weight placed correctly on the machine. Adjust spring pre-
load to achieve the 1 1/2 sag dimension on X--Tra 10 or 4" on all EDGE and PRO X models.
S Unloaded (Free) Sag: When the rider gets off the machine, the suspension should return to 1/2 of sag.
If the sag is less than 1/2 stiffer springs may be needed. If it is greater than 1/2 softer springs may be needed.
This may seem backwards at first, but if the spring is too soft, the preload must be greatly increased to prevent
excess loaded sag. This shows up in the form of less unloaded sag. Therefore, a stiffer spring is required. If
the spring is too stiff, the preload will have to be backed off, and unloaded sag will be excessive. This is a very
important step because the proper spring will also help ensure correct weight transfer.

Shock Tuning

The shocks work in two directions. Compression damping prevents the shock from bottoming hard while rebound
damping keeps the shock from springing back too fast. On Indy Select shocks, the compression damping can
be changed by turning the adjuster screw. Refer to shock section in this chapter for adjustment. NOTE: When
we refer to high and low speed, we are referring to the speed of the shock shaft or valve, not vehicle speed.

Rebuildable Shocks

Begin by taking the shocks apart, inspecting all parts for damage, and changing the oil. Even new shocks should
get an oil change after break in to clean break-in material from the shocks and valve body.
If oil is low, inspect seal cap O-Ring and seals for damage. If air or foam is evident in the oil, the O-Ring in the
floating piston must be replaced. After changing the oil reassemble shocks, making sure oil level, floating piston
depth (IFP), and nitrogen pressure are correct.
The use of nitrogen in Walker Evans Racing Shocks and Ryde FX
treme temperatures. Don't overcharge the shocks. Excess nitrogen pressure may cause seal "suction" and pre-
vent proper shock action. If too much oil is added, or if the IFP depth is set incorrectly (too low) shock travel will
be limited, and shock damage could result.
REAR SUSPENSION/TRACK/TRACTION
shocks provides consistent damping at ex-
7.5