BOMBARDIER 1996 Ski-doo MX Z440 Handbook page 234

Section 05 TRANSMISSION SYSTEM
Driven pulley cams are helices. A helix is measured in " lead" . Lead is the distance a point moves
along the axis of rotation in one revolution of the helix. (Screw threads are a helix. )
The helix angle is computed from the lead and the circumference of the helix.
AOIDIWS
Helix angles for Ski-Doo cams are measured at the mean circumference of the cam. This is at the
midpoint of the ramp surface.
AOIDIXS
L
Tan A = ~ or L = C x Tan A
Where :
L = Lead in inches
C = Circumference on outside diameter
A = Cam angle on outside diameter
o
NOTE : C(mean) for all Formula and Blizzard cams is 247 mm (9.72 in)
D ~~,,n) for all Formula and Blizzard cams is 78.6 mm (3.09 in)
Example :
L = 9.72" TAN 44°
X
L = 9.72 .966
X
L = 9.39 inches of lead
05-30
Tan A =
Lead
Circumference
Circumference (mean) = 2 n R
R
Lead