Figure 9. Installing Rear End Plate
The current thrust plate is 0.260 inch thick. The former plate
was 0.180 inch thick.
Position the rotors so that the missing serrations on the gear end of the rotor shafts are 90
apart. This is accomplished by placing the rotors in a "T" shape, with the missing serration in the upper rotor
facing to the left and the missing serration in the lower rotor facing toward the bottom (Fig. 12). Install the
shims and spacers in the counterbore in the rear face of the rotor gears. Then place the gears on the ends of
the shafts with the missing serrations in alignment with the missing serrations on the shafts.
Tap the gears lightly with a soft hammer to seat them on the shafts.
Then rotate the gears until the punch marks on the face of the gears match. If the marks do not match,
reposition the gears.
Wedge a clean cloth between the blower rotors. Use the gear-retaining bolts and plain washers
to press the gears on the rotor shafts (Fig. 10). Turn the bolts uniformly until the gears are tight against the
shoulders on the shafts.
Remove the gear retaining bolts and washers. Place the blower drive cam pilot in the
counterbore of the upper gear and start the gear retaining bolt in the rotor shaft. Place the gear washer on the
face of the lower gear and start the gear-retaining bolt in the rotor shaft. Tighten the bolts to 25-30 lb ft (34-41
Check the backlash between the blower gears, using a suitable dial indicator. The specified
backlash is 0.0005 to 0.0025 inch with new gears or a maximum of 0.0035 inch with used gears.
Time blower rotors.
After the blower rotors and gears have been installed, the blower rotors must
Figure 10. Installing Blower Rotor Gears