Table of Contents
Advertisement
Weight
Ch~rt
Part
Weight in Outside
Color
Number
Grams
Diameter
Code
0146-227
1.000
.400"
Aluminum
0146-225
1.500
.463"
Aluminum
0146-226
2.000
.521"
Aluminum
0146-159
2.500
.377"
White
0146-108
3.058
.406"
Yellow
0146-175
3.725
.437"
Red
0146-135
4.479
.471"
Black
0146-379
4.577
.473"
Black
0146-176
4.675
.500"
Green
0146-107
4.958
.491"
White
0146-279
5.457
.511"
Black
0146-106
5.958
.530"
Red
0146-278
6.475
.549"
Black
f"\146-123
6.992
.568"
Yellow
146-105
7.858
.598"
Black
0146-286
8.800
.629"
Red
0146-136
9.279
.644"
Green
0146-104
9.750
.665"
White
0146-166
10.600
.684"
Red
0146-307
11.300
.703"
Yellow
0146-314
12.000
.723"
Green
0146-345
15.000
.798"
White
0146-308
18.000
.873"
Black
Weights
Each arm of the spider assembly has two weights,
a roller and a bushing secured to the arm by a
small bolt and lock nut. The weights provide an
outward centrifugal force which causes the
rollers to move up the ramps. As engine rpm is
increased, outward centrifugal force becomes
strong enough to overcome the force of the
spring and causes the moveable sheave to push
the drive belt against the stationary sheave. By
increasing the weight, the centrifugal force
generated is greater and the drive clutch will
'lift up" at lower rpm. Conversely, by installing
.;Ihter weights, the generated centrifugal force is
less and the clutch takes longer (higher rpm
range) to "shift up".
Arctic weights are available from one gram to
over 18 grams.
Ramps
Drive clutch ramps affect the overall shift pattern
of the drive clutch. Ramps that are properly
matched for a given engine allow smooth
engagement and maintain maximum horsepower
through the rpm range of the shift pattern.
The design of the ramp is dependent on the
torque curve of the engine. A high rpm racing
engine uses a ramp profile that is much different
than that of a low rpm, "family" sled.
The total distance of the rollers on the ramps for
the complete shift from engagement through
"top end", where the drive clutch is in a 1:1
relationship with the driven clutch, is only about 1
inch. Considering this, it is easy to see why a
thorough understanding of the close relationship
between ramp profile and shift characteristics is
necessary before any changes are made.
Fig. 6-2
0725-234
Ramp Profile and Shift Characteristics
As previously stated, the Arctic drive clutch has
three major variables which are closely related
and which greatly affect the overall power
transfer efficiency of the snowmobile. These
variables, the spring, the weights and the ramp
profile, are matched at the factory for each
different snowmobile model and engine size. The
factory set-up provides optimum power transfer
efficiency for average customer usage. However,
by understanding these clutching variables, the
Arctic drive clutch can be customized to suit
almost any individual performance requirement.
From the discussion on the spring, we know that
the engagement speed can be changed by either
increasing or decreasing the spring rate. Also
affecting engagement speed, as well as determin-
ing the characteristics of the overall shift pattern,
is the profile of the ramps. The profile of the
ramps will either increase or decrease the
engagement speed (rpm).
82
Advertisement
Table of Contents
