Snowmobile Polaris (2006 year). Manual - part 38

7.6

CLUTCHING

DRIVE BELT REMOVAL WITH POLARIS 

DRIVEN CLUTCH

To ensure belt life, install belts so they operate in the same 
direction of rotation. Position the identification numbers so 
that you can read them standing on left side of machine. This 
will keep the belt rotating in the same direction. If belt has 
been operated with numbers readable from right side of 
machine, re-install belt in this direction.

Before attempting to remove the drive belt, make certain that 
the snowmobile was in forward motion. Turn the key off so 
that the engine has come to a complete stop.

1.

Remove the clutch guard retaining pin and open the clutch
guard.

2.

Apply and lock the parking brake.

3.

Grasp belt firmly midway between clutches and pull
upward and rearward to open the driven clutch sheaves
(A). Remove the belt from the driven clutch and then from
the drive clutch (B, C).

4.

Release the parking brake.

BELT INSTALLATION (POLARIS DRIVEN 
CLUTCH)

1.

Drop the drive belt over the drive clutch and pull back the
slack (C).

2.

Turn the driven clutch moveable sheave clockwise while
at the same time pushing inward and forcing the belt down
between the sheaves.

3.

Hold the belt down between the sheaves and roll the
bottom portion over the outer clutch sheave. Once
installed, be sure to work the belt to the outer edge of the
sheave. 

4.

Be sure to release parking brake if applied.

5.

Close the clutch guard and reinstall the retaining pin.

WARNING

 Inspect the condition of the drive belt and clutch 
sheaves for damage wear, or belt residue during pre-
ride inspections. Clean with a non-oil base cleaner 
such as isopropyl alcohol

7.7

CLUTCHING

DRIVE SYSTEM TERMINOLOGY

SYSTEM OVERVIEW

The Polaris drive system is a centrifugally actuated variable 
speed belt drive unit. The drive clutch, driven clutch, and belt 
make up the torque converter system. Each clutch comes from 
the factory with the proper internal components installed for 
its specific engine model. Therefore, modifications or 
variations of components at random are never recommended. 
Proper clutch setup and adjustments of existing components 
must be the primary objective in clutch operation diagnosis.

DRIVE SPRING

The drive spring opposes the shift force generated by the 
clutch weights, and determines the neutral RPM, engagement 
RPM, and wether the engine RPM remains flat, rises, or falls 
during shift out. When changing only the drive spring, 
installing a spring with a lower pre-load rate will result in a 
lower engagement RPM speed, while installing a spring with a 
higher pre-load rate will result in a higher engagement RPM. 

CLUTCH WEIGHT

The clutch weights generate centrifugal force as the drive 
clutch rotates. The force generated changes in relation to the 
engine RPM and with specified weight of each clutch weight. 
When changing only the clutch weights, a lighter weight will 
result in a higher engagement RPM, lower shifting force, and 
higher shift out RPM. Installing heavier weights has the 
opposite effect

NEUTRAL SPEED

Engine RPM when the force generated by the clutch weights is 
less than the pre-load force generated by the drive spring. In 
this mode, the drive clutch is disengaged.

ENGAGEMENT RPM

Engine RPM when the force generated by the clutch weights 
overcomes the drive spring pre-load force and the moveable 
sheave begins to close or “pinch" the drive belt. The 
engagement mode continues until no more belt slippage occurs 
in the drive clutch. Once 100% belt engagement is achieved, 
the sled will accelerate along the low ratio line until the drive 
clutch up shift force overcomes the opposing shift force 
generated by the driven clutch.

SHIFT OUT OVERREV

Engine RPM that spikes above the desired operating RPM 
speed. The shift out RPM should come down to the desired 
operating RPM, but never below, after the driven clutch begins 
to open.

SHIFT OUT RPM

Engine RPM at which the up shift force generated by the drive 
clutch overcomes the shift force within the driven clutch. In 
this mode, the drive clutch will move the belt outwards, and 
the driven clutch will allow the drive belt to be pulled down 
into the sheaves.

During WOT operation, the shift out RPM can be seen as the 
maximum, sustained RPM displayed on the tachometer. The 
shift out RPM should be the same RPM as the recommended 
engine operating RPM. If the shift out RPM is above the 
recommended engine operating RPM, install heavier drive 
clutch weights. If the shift out RPM is below the 
recommended engine operating RPM, install lighter drive 
clutch weights.

The shift out RPM should remain constant during both the 
upshift and back shift modes.

DRIVEN SPRING

A compression spring (Team driven clutch) or torsional spring 
(Polaris P-85 driven clutch) works in conjunction with the 
helix, and controls the shift rate of the driven clutch. The 
spring must provide enough side pressure to grip the belt and 
prevent slippage during initial acceleration. A higher spring 
rate will provide more side pressure and quicker back shifting 
but decreases drive system efficiency. If too much spring 
tension exists, the driven clutch will exert too much force on 
the belt and can cause premature belt failure.

CAUTION

All clutch maintenance repairs must be performed only 

by an authorized Polaris service technician who has at-

tended a Polaris sponsored service training seminar 

and understands the proper procedures as outlined in 

this manual. Because of the critical nature and preci-

sion balance incorporated into the drive clutch, it is ab-

solutely essential that no attempt at clutch disassembly 

and/or repair be made without factory authorized spe-

cial tools and service procedures. Any unauthorized 

modifications to clutches, such as adding or removing 

weights, will void the warranty

.

7.8

CLUTCHING

BACK-SHIFTING

Back-shifting occurs when the track encounters an increased 
load (demand for more torque). Back-shifting is a function of 
a higher shift force within the driven clutch then within the 
drive clutch. Several factors, including riding style, 
snowmobile application, helix angles, and vehicle gearing 
determine how efficient the drive system back-shifts. The 
desired engine operating RPM should never fall below 200 
RPM when the drive system back-shifts.

FINAL GEARING

The final drive gear ratio plays an important role in how much 
vehicle load is transmitted back to the helix. A tall gear ratio 
(lower numerical number) typically results in lower initial 
vehicle acceleration, but a higher top-end vehicle speed. A 
lower gear ratio (higher numerical number) typically results in 
a higher initial vehicle acceleration, but a lower top-end 
vehicle speed.

Choosing the proper gear ratio is important to overall drive 
system performance. Lowering the final drive gear ratio will 
compress the MPH scale between the low and high ratio lines, 
while raising the final drive gear ratio will expand the MPH 
scale between the low and high ratio lines.

When deciding on which gear ratio to use, the operator must 
factor in the decision where the snowmobile will be ridden, 
what type of riding will be encountered, and the level of 
performance the operator hopes to achieve.

Gearing a snowmobile too low for extended high-speed runs 
may cause damage to the drive belt and drive system, while 
gearing a snowmobile too high for deep-snow, mountain use 
may cause premature belt and clutch wear.

Typically, it is recommended to gear the snowmobile with a 
slightly higher ratio than the actual top speed the snowmobile 
will ever achieve.

1:1 Shift Ratio

A 1:1 shift ratio occurs when the drive clutch and the driven 
clutch are rotating at the same RPM. In this mode, the drive 
system is at its highest efficiency. Drive system efficiency 
falls off past the 1:1 shift ratio.

The mathematical vehicle speed for a given gear ratio at a 1:1 
shift ratio is represented in the chaincase gearing charts 
located in the Final Drive Chapter.

LOW / HIGH RATIO LINES

The low ratio line is the mechanical position when the drive 
belt is all the way down into the drive clutch, and all the way 
out on the driven clutch. The high ratio line represents when 
the drive belt is all the way out on the drive clutch, and all the 
way in on the driven clutch.

Note that the high ratio line is past the ideal 1:1 shift ratio.

DRIVEN HELIX / RAMP

The helix cam is the primary torque feedback component 
within the driven clutch, regardless of driven clutch type. The 
beginning angle of the helix must transmit enough torque 
feedback to the moveable sheave in order to pinch the drive 
belt while minimizing belt slip. The 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.

7.9

CLUTCHING

CENTRIFUGAL DRIVE SYSTEM

THEORY OF OPERATION

The graph illustrates what occurs in a properly tuned 
snowmobile drive system during an idle speed to WOT (wide 
open throttle) pull. Note that the shift out overrev occurs for a 
brief amount of time and drops back to the desired engine 

operating RPM. The low and high ratio lines are a function of 
component design.

NOTE:  Shift out overrev is not detrimental to overall 
efficiency of the drive system as long as the RPM 
drop does not fall below the desired operating RPM. 
The use of the new drive system technologies, 
tighter tolerance components and refined drive 
system calibration in Polaris snowmobiles has 
virtually eliminated shift out overreving.

DRIVE CLUTCH

OPERATION

The drive, or primary, clutch is an RPM sensing device. The 
main functions of the drive clutch is to control the neutral 
RPM speed, initial engagement RPM, and desired engine 
operating RPM. The drive clutch works by using the principle 
of centrifugal force to react to engine RPM. At idle speed, the 
moveable sheave is held open by the drive spring pre-load 
force. As engine speed increases, the centrifugal force 
generated by the clutch weights will overcome the drive spring 

pre-load force, and begin to close the moveable sheave. This 
action engages, or “pinches" the drive belt.

In a properly tuned clutch, the desired operating RPM should 
be reached immediately after clutch engagement under full 
throttle (WOT) conditions. The desired engine operating RPM 
is the recommended operating RPM listed for each model. 
This information can be found in each models' general 
specification table. To ensure optimum power, the 
recommended operating RPM must be maintained throughout 
the upshift and backshift modes.