GMC 4000 Series Service Manual page 142

stud nuts, then remove shift unit from axle.
6. Remove wire cable clip from shift unit
cover. Note to which terminal each wire is attach­
ed, then disconnect the two wires from shift unit
term inals.
ELECTRIC SHIFT UNIT OVERHAUL
The following information is provided on the
assumption that shift unit has been tested and re­
moved as previously instructed.
DISASSEMBLY (EATON AND CORP.)
Key numbers in text refer to figure 11.
1. Remove six screw s (28) and lock washers
w hich attach c o v e r (26) to sh ift m otor housing (8).
Drain lubricant from housing. Remove gasket (25).
2. After removing cover (26), the drive screw
(20) nut will be at either top or bottom depending
upon the position in which the control switch was
last left.
3. By turning drive screw, run nut from top
or bottom to the center of the screw (fig. 12).
IMPORTANT: The previous step is essential
to prevent damage to drive nut contact bumper,
and is also necessary in assembly.
4. Remove shift fork actuating lever (22), tor­
sion spring (23), and spring winding lever (24) as
an assembly by pulling shaft (21) up. Swing the
assembly away from the drive nut and lift out of
the housing (fig. 13).
5. Remove three screw s and lockwashers (16)
which attach bearing cover (15). Remove cover and
gasket (14).
6. Push down on drive screw assembly (20)
until bearing assembly (12) is free of housing.
7. Insert screwdriver in drive slot of screw
(fig. 14), then remove bearing lock nut (13) and
bearing with snap ring (12). Drive screw assembly
(20) can then be lifted out of housing.
8. Remove the two lock nuts (19) from switch
term inals (17). Pull off motor wires (fig. 15).
9. Remove three screw s and lock washers (1)
which attach motor cover (4) to housing. Pull out
motor (6) with cover (4) attached to motor with
two cover nuts (2). Remove grommet (7).
10. Remove two jam nuts (9) and fiber washers
(10) from outside of housing. On inside remove
switch center screw (18). Pull out automatic switch
(17) as shown in figure 17.
11. Do not disassem ble the shift fork actuating
lever (22), torsion spring (23), and spring winding
lever (24) unless necessary to replace one of the
parts. If necessary to disassem ble, mount assem ­
bly in vise as shown in figure 18. Turn spring
winding lever (24) clockwise and pull to separate.
DISASSEMBLY (ROCKWELL) (Refer to Fig. 18)
1. Remove three screw s and lockwashers (16)
which attach bearing cover (15) to bottom of shift
G M C S E R V I C E M A N U A L
unit housing. Remove cover and gasket (14).
until bearing assembly (12) is free of housing.
(fig. 14); then remove bearing lock nut (13) and
bearing with snap ring (12). Drive screw assembly
(20) can then be lifted out housing.
terminals (17). Pull off motor wires (fig. 15).
which attach motor cover (4) to housing. Pull out
motor (6) with cover (4) attached to motor, with
two cover nuts (2). Grommet (7) can then be re­
moved.
(10) from outside of housing. On inside remove
switch to housing screw s (18). Remove automatic
switch.
spring winding lever (22) unless necessary to re­
place one of the parts. If necessary to disassem ble,
REAR AXLE A N D CONTROLS
Figure 16— Shift Unit Cover Removed(Rockwell Axles)
2. Push down on drive screw assembly (20)
3. Insert screwdriver in drive slot of screw
4. Remove the two lock nuts (19) from switch
5. Remove three screw s and lock washers (1)
6. Remove two jam nuts (9) and fiber washers
7. Do not disassem ble torsion spring (23), and
Figure 1 7 — D isa sse m b lin g Torsion Sp rin g from Lever
Sec. 4A
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