GMC 4000 Series Service Manual page 29

Sec. 1
Page 22
GENERAL MAINTENANCE
Figure 4 — Blade A n g le Adjustment (Tilt C a b )
3. Arm can be reinstalled in any one of sev­
eral positions due to serrations on pivot shaft and
in arm cap.
TILT CAB MODELS
Wiper Arm Adjustment (Fig. 3)
Wiper arm can be repositioned on pivot shaft
to provide proper sweep as follows:
1. Remove hex crown nut and washer which at­
tach wiper arm to knurled driver and pivot shaft.
2. Relocate arm on driver to desiredposition.
3. Install washer and hex crown nut.
Blade Angle Adjustment (Fig. 4)
To change angle of wiper blade on arm, loosen
cap screw which attaches blade to arm. Rotate
blade to new position against adjustment washer
on arm, then tighten cap screw firm ly. When wiper
motor is in "PARK" position, blade should be ap­
proximately parallel to the horizontal windshield
seal.
G M C S E R V I C E M A N U A L
Figure 5 — W iper M otor a n d Linkage (Conventional Cab)
WIPER A RM TRANSMISSION A N D
LINKAGE REPLACEMENT
(CONV. CAB MODELS)
REMOVAL (Fig. 5)
NOTE: Both right and left wiper transmission
units with connecting link rod and motor link rod
are replaced as an assembly.
1. Remove both right and left wiper arms
from transm issions. Pull arms outward to disen­
gage arm retaining clip.
2. Remove special retaining nut, steel washer,
and seal washer from each transm ission at front
of windshield.
3. Underneath the dash, remove defroster air
outlet tubing if necessary, and any other item s to
allow access to transmission linkage.
4. At motor crank arm under dash, remove
the two nut assem blies which secure link rod to
arm. Disengage end of rod from arm.
NOTE: Alternate methods of obtaining access
to these two nuts are to move the wiper motor
forward from the cowl opening or to remove the
ash tray panel.
5. Using a short cr o ss-rec ess type screw ­
driver, remove two screws and washer assem blies
which attach each transmission unit to underside
of cowl. Remove the transm issions with linkage
as an assembly.
INSTALLATION (Figs. 5 and 7)
Perform the installation procedures in the
reverse of the "Removal" procedures. Make sure
the seal washers located below the transmission
units at front of windshield are new or in good
condition before installing; otherwise leakage may
occur later at these two points.
IMPORTANT: Before locating the wiper arms
on transmission shafts, make sure wiper motor
was stopped in the "PARK" position (fig. 7). Oper­
ate motor, then turn switch off and allow it to stop
in "PARK" position. If motor is not in "PARK"
position and arms are installed, the arm travel