Effects Of The Driven Pulley Spring - BOMBARDIER 1996 Ski-doo MX Z440 Handbook

Section 05 TRANSMISSION SYSTEM

EFFECTS OF THE DRIVEN PULLEY SPRING

The driven pulley spring is needed to keep the plastic slider buttons in contact with the cam and to
provide enough side force on the belt in the low gear position to allow initial acceleration while the
torque rises to a point where the torque sensing cam begins to take over. At full load, the driven
pulley spring has much less effect on the driven pulley shifting sequence than does the cam,
especially at low shift ratios. At the part throttle loads at low ratios, the spring has the main effect
on the shift characteristics of driven pulley.
Increases in the driven pulley spring preload will bring the engine speed up before the pulley starts
shifting and will help backshift the clutch quicker. Decreasing the preload will allow a faster upshift
but a slower backshift thus lowering the engine RPM.
o
NOTE : Control of the engine speed is done by calibrating the engine pulley not by
adjusting the driven pulley spring preload. An attempt to lower the engine RPM by decreasing
the spring preload in the driven pulley will result in belt slippage on acceleration. An attempt to
increase engine RPM by increasing the preload will result in excessive drive belt wear and
decreased efficiency in the transmission.
The driven pulley spring preload is listed in the basic specifications for all our machines. This
The preload figure given in our specifications is quoted in kg (lb) of force for each machine, not in
inch-pounds or foot-pounds of torque. A figure given in units of torque would require multiplying
the radius of the pulley by the pull recorded on the scale. Our figures are quoted for each pulley
size and it is only necessary to record the pull of the spring by attaching a scale to the rim of the
pulley. The scale must be positioned at 90° to the radius of the pulley. Holding the fixed half of the
pulley still, pull until the sliding half just begins to rotate. At this point, read the scale.
A01B18S
I
TYPICAL
Spring scale hook(P/N 529 006500)
05-26