GMC 4000 Series Service Manual page 27

Sec. 1
Page 20
GENERAL MAINTENANCE
IN S T A L L IN G IN SERT IN SEA L
Figure 1 — Installing Insert-Retained Class
REMOVAL (Fig. 1)
If cracks in glass extend to outer edge of
glass, mark cab or cowl with chalk at these points
so that weatherstrip flange in cab opening can be
examined later for possible distortion.
Protect the interior paint finish by placing a
protective covering over steering wheel and dash
panel. Mask around the windshield opening and lay
a suitable cover over hood and fenders.
CAUTION
ALWAYS W EA R HEAVY GLOVES TO
P R E V E N T POSSIBLE
HANDLING GLASS.
1. Pry end of insert out of rubber seal with a
pointed tool; pull insert completely out of seal.
2. With aid of an assistant to hold glass out­
side cab, push glass forward from inside cab.
INSPECTION
Due to the expanse and contour of the wind­
shield, it is imperative in the event of a strain
break that the windshield opening be thoroughly
checked before installing a replacement windshield.
1. Check for the following conditions at the
previous marked point of fracture:
G M C S E R V I C E M A N U A L
INJURY WHEN
C le a ra n c e Blocks;
(J -9 3 1 6 )
Figure 2 — Checking Class Clearances (Tilt Cab)
a. Chipped edges on glass.
b. Irregularities in body opening.
c. Irregularities in rubber channel weather­
strip.
2. Remove all sealer from flange and body
around windshield opening.
3. Check flange area for solder, weld high
spots, or hardened spot-weld sealer. Remove all
high spots.
GLASS-TO-OPENING CLEARANCE
CHECK (TILT CAB)
Before installing new glass, check glass open­
ing for proper clearance, using five special spacer
blocks (J-9316) as shown in figure 2. With the aid
of an assistant, place blocks around perimeter of
new glass, two at bottom and top and one at outer
side of opening. A 5/16to 3/8 inch clearance should
exist between glass and opening flange. Insert
blocks into gap, then rotate blocks perpendicular
to flange surfaces. If all blocks cannot be installed,
rework metal flange or grind off edge of glass at
the side where block or blocks could not be in­
stalled.
C A U T I O N : DO NOT strike glass
against body metal. Chipped edges on the
glass can lead to future breaks.
If glass clearance is too sm all and glass is to
be ground off, place a strip of tape on a line where
glass is to be removed. Grind up to edge of tape.
If glass clearance is found too large, braze a
continuous piece of 1/8 inch diameter wire to edge
of cab windshield glass opening flange. This will
provide a closer glass and seal fit.
NOTE: Add build-up to flange where n eces­
sary. Usually the building up to only one side and
one-half way around one corner will provide proper
glass and seal fit. Taper off ends of build-up to
conform to edge of glass, otherwise glass break­
age may occur, originating at a point adjacent to
the end of flange build-up.