Toro 20330 - Low Wheel Walk Power Mower Service Manual page 104

BBC / BOS / BCS
6. Install the BBC fl ywheel onto the crankshaft, making
certain that the slots in the BBC fl ywheel align with
the bumps on the bottom of the self-propel pulley
(Fig. 175).
A. Bumps
Note: If the crankshaft nut is tightened with these
bumps misaligned, the boss at the bottom of
the keyway on the self-propel pulley will break
and the self-propel pulley will be free to slide
up and down on the crankshaft (Fig. 176).
This can result in noisy operation, premature
belt wear, and belt jumping.
A A
A. Boss
6-18
A A
Fig 175 3428-0117
B. Slots
Fig 176 3428-0116
7. Press the bearings into the bearing block, using an
arbor press. Press only on the outer race, otherwise
bearing damage will result (use an appropriately
sized arbor or a 1-1/8" (28mm) socket to press the
bearing into the block).
8. Make sure that the foam rubber anti-vibration pads
are in place on the brake drum and assemble the
brake drum bearing block and BBC screws onto the
crankshaft as shown in Figure 177. Secure with the
crankshaft nut.
Note: Crankshaft nut torque: 45 – 70 ft-lbs. (61 –
B B
95 Nm)
CAUTION! As with disassembly, the fl ywheel can
be wedged to tighten the nut. Make sure the bumps
in the self-propel pulley stay engaged with the
fl ywheel or the pulley will be damaged.
Note: Make sure that the blade bolts are properly
aligned before tightening the crankshaft nut.
9. Install the BBC cover with the four fl anged head self-
tapping screws.
10. Install the BBC screen, the blade spacer, the blade,
and the anti-scalp cup onto the BBC screw and
secure with the two fl anged nylon locknuts. Torque
to 300 in-lbs. (37 Nm).
Note: Blade locknut torque: 300 in-lbs. (37 Nm)
Fig 177 MVC-726
WPM Drive Systems Manual