Polaris 2003 Pro X Service Manual page 242

REAR SUSPENSION/TRACK/TRACTION
Springs
Two types of springs are employed in Polaris suspen-
sions, coil springs and torsion springs. Following is some
of the terminology used when referring to coil springs.
S Free length - the length of a coil spring with no load ap-
plied to the spring
S Installed length - the length of the spring between the
spring retainers. If the installed length of the spring is
less than the free length, it will be pre-loaded.
NOTE: All springs must have preload or damage to the
retainers and shock may occur.
S Spring rate - the amount of force required to compress
a coil spring one inch. For example, if 150 pounds of
force are required to compress a spring 1 inch, the
spring rate would be 150 #/in.
S
Straight rate spring - the spring requires the same amount of force to compress the last one inch of travel as
the first one inch of travel. For example, if a 150 #/in. spring requires 150 pounds of force to compress it one
inch, 300 pounds of force would compress it two inches, 450 pounds of force would compress it three inches,
etc.
S Progressively wound spring - the rate of the spring increases as it is compressed. For example, a 100/200
#/in. rate spring requires 100 pounds of force to compress the first one inch, but requires 200 additional
pounds to compress the last one inch.
S Dual Rate Springs - See page 6.8 for dual spring rate information.
When a bump is encountered by the suspension, the force of the bump compresses the spring. If the force were
450 pounds, a 100 #/in. spring would compress 4.5 inches. A 150 #/in. spring would only compress 3 inches.
If the suspension had 4 inches of spring travel the 100 #/in. spring would bottom out, while the 150 #/in. spring
would have one inch of travel remaining.
Torsion springs are much like coil springs, although
shaped differently. The rate of the torsion spring is con-
trolled by the free opening angle, the installed opening
angle, the wire diameter of the spring, and the number of
coils.
7.4
Coil Spring
Length
Torsion Spring
Load reduces
opening angle
Load
Installed
Length
Wire
Dia.