Introduction; Removal; Inspection - Triumph Thunderbird Service Manual

Balancer
1. Tool T3880039
2. Timing hole in crankcase
4. Release the dead shaft screw and washer and slide
out the dead shaft, supporting the balancer shaft as
you do so.
Turn the crankshaft until the timing pin 13880039
can be inserted through the hole in the upper
crankcase and into the idler gear.
3.
The Thunderbird is fitted with two balancer shafts, one
forward of the crankshaft and one behind it. Each
balancer has the effect of a pair of counterbalance
weights, which create an equal amount of energy in the
opposite direction, and at the same time as that produced
by the crankshaft, pistons and connecting rods. Because
the opposing pulses occur at the same point of crankshaft
rotation, and are of an equal magnitude, a state of
equilibrium or balance is reached.
The balancer shaft drive gear is fitted with a backlash gear,
to reduce backlash between the gear teeth and therefore
reduce noise. The backlash gear uses a hunting tooth
design, which means it has one less tooth than the
balancer shaft driven gear. The balancer shaft driven gear
has 55 teeth, the backlash gear has 54 teeth. This design
has the effect of eliminating any backlash between the
two gears. However it also means that the timing marks
located on the backlash gear will only align with the
timing marks on the balancer shaft driven gear once every
55 revolutions of the balancer shaft. Therefore it is
essential to correctly align the backlash gear with the
balancer shaft driven gear as described in the following
instructions.
Removal
Introduction
Before starting work, ensure the motorcycle is stabilised
and adequately supported. This will help prevent it from
falling and causing injury to the operator or damage to
the motorcycle.
Note:
• The removal and installation procedure for
either balancer shaft is the same. This
procedure describes the replacement of the
front balancer shaft.
1. Remove the engine (see page 9-2).
2. Separate the crankcase halves (see page 5-4).
5. Remove the balancer shaft.
6. Discard the dead shaft screw and retain the washer
for re-use.
Inspection
1. Inspect all gears for chipped or missing teeth and for
overheating (blue discolouration).
2. Inspect all bearings for signs of overheating (blue
discolouration), seizure and any other damage.
Check that all bearings rotate smoothly and without
tight spots.
SelVice Manual - Thunderbird
6.3