Balancing Of Pulleys; Truing Pulley Surfaces; Windage Plates - BOMBARDIER 1996 Ski-doo MX Z440 Handbook

BALANCING OF PULLEYS

Each half of Ski-Doo driven pulley is individually balanced. This means that parts can be interchanged
and that no alignment marks are needed for assembling for the complete assembly to be in
balance.
The TRA clutch is similar to our driven pulleys in the sense that each major component is balanced
separately.
However, there are arrows to align when reassembling this clutch. The first one is on the spring
cup or cover to the sliding half. The next is between the governor cup and the sliding half. Once
these have been indexed properly, the fixed half can be inserted into the clutch assembly and no
alignment is needed between the inner pulley and the sliding half on 1994 and older TRA's. 1995
inner pulleys * have an alignment mark.
Some 1995 and 1996 models have the new cushion drive, governor cup as standard equipment.
This governor cup can't be retro-fitted to other non-cushion drive vehicles due to weight imbalance.
Use only complete clutch assemblies on non-cushion drive vehicles.

TRUING PULLEY SURFACES

The surfaces of a die cast pulley sheave are not always perfectly true. The casting cools in the die
at slightly different rates which makes the surface uneven. Trueing the surface in a lathe can
increase efficiency of the transmission. The driven pulley sheaves have a 13.75° angle while TRA
drive pulley sheaves have a 12° angle. Always remove as little material as possible when trueing
these surfaces. Pulley halves need to be rebalanced after any machining.

WINDAGE PLATES

"Windage plates" which cover the reinforcing webs on each sheave simply make the pulley more
aerodynamic and reduce the amount of energy lost from "pumping air". The use of these plates or
covers can make a difference of one to two MPH on top end. The down side of the use of these
plates is the increase in sheave temperature due to the reduction of air cooling.
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