Chevrolet 70 Series 1970, Service Manual

Page: 52 / 841

CAB AND BODY MOUNTINGS 1-21
2. Follow Steps 1 through 3 under "Piston
Packings R eplacem ent" m entioned p re v io u sly .
3. Move rack to center of cylinder and p lace
a little g r e a se in the teeth of the gear rack.
4. Install shaft and gear a ssem b ly (View A),
making su re that the teeth match in the rack. (The
la s t tooth in s e c to r should m esh with the la s t tooth
of rack at either end.)
5. A ssem b le top co v er, making su r e it is m
the sam e position a s when rem oved. Tighten sc r e w s
se c u r e ly .
V alve Stop Unit A ssem b ly R eplacem ent
1. R em ove valve head a ssem b ly a s outlined
p rev io u sly .
2. Move gear rack a ssem b ly as c lo s e to open­
ing a s p o ssib le .
3. Rem ove sc r e w fro m end of p iston a ssem b ly
View B.
4. R eplace valve stop unit a ssem b ly and tighten
sc r e w se c u r e ly .
B roken Gear Segm ent R eplacem ent
R em ove top p la te, shaft, and gear a ssem b ly
a s outlined under "Piston P ackings Replacem ent"
and rep la ce a s outlined p rev io u sly under "Shaft
R ep lacem en t.”
Stop S crew s' Adjustm ent
IMPORTANT: The follow ing in stru ction s must
be carefully follow ed, o th erw ise sc r e w s w ill be
im properly set:
1. Turn w iper on and allow to operate at slo w ­
e st p o ssib le speed.
2. R em ove top cap by prying up with s c r e w ­
d riv er, forcin g out riv e ts.
3. L oosen lock nut, V iew A, figu re 24, and run
down stop s c r e w , View A, figure 24, until w iper is
stopped by sc rew .
4. B ack out sc r e w just enough to p erm it w iper
to operate. With stop sc r e w in th is position , run
down and tighten lock nut.
5. R epeat the p rev io u s operations on the r e ­
m aining stop scr ew .
AIR-OPERATED WINDSHIELD WIPERS
(SERIES 90 ALUM. TILT CAB)
GENERAL INFORMATION
Two a ir -o p e ra ted p isto n -ty p e m otors (fig. 25)
a re mounted in sid e cab beneath dash panel and are
read ily a c c e s s ib le for s e r v ic e . Both m otors r e c e iv e
air p r e s s u r e through a sin g le a ir control v a lv e (fig.
30) that is located on c en ter co n so le below h eater
control panel.
W indshield w ip ers a r e designed to require no
sp e c ia l m aintenance and should rem ain undisturbed
u n le ss m otors fa il to function. B efo re rem oving
m otors, check control v a lv e, tubing, and connec­
tion s fo r plugging o r leak age. Make su r e that ade­
quate a ir p r e ssu r e is d elivered to m otors.
W IP E R A R M A D JU S T M E N T (F ig . 26)
O peration of w indshield w ip ers can be o b se r v ­
ed without wetting w indshield g la s s by in sertin g a
IX" x 1 /1 6 ” cotter pin o r nail into hole at b ase of
each w iper arm , adjacent to hinge a rea , after p u ll­
ing arm s forw ard slig h tly . T his w ill prevent blades
from contacting dry w indshield when w ip ers are
operated.
To adjust w iper blades to p rovide m axim um
v isib ility , turn on w ip ers and o b ser v e sw eep of
a r m s. P ark w ip ers and m easu re perpendicular
d istan ce from horizontal w indshield w eatherstrip
to ou ter tip of w iper blade. D im ension should m ea­
su r e four in ch es. If arm adjustm ent i s required,
p ro ceed a s follow s:
1. While holding arm to prevent dam age to
linkage, rem ove crown nut (and w ash er if used)
which reta in s w iper arm to ser r a te d pivot shaft.
2. U sing a h ex-w rench, lo o sen bolt which
clam ps arm head to pivot shaft.
3. With w iper m otor in "PARK” p osition , r e ­
m ove and rep osition w iper arm on pivot shaft so
that dim ension from outer tip of w iper blade to
h orizontal w indshield w eath erstrip is four in ch es.
4 . In stall crown nut (and flat w asher) on pivot
shaft. Hold w iper arm and tighten crown nut to 20-
25 foot-pounds torque.
5. Tighten hex-head clam p bolt firm ly .
6
. O perate w ip ers on w etted w indshield and
o b serv e blade sw eep . P ark blades and rech eck
dim ension from tip of blade to w eatherstrip in sert.
IMPORTANT: DO NOT attem pt to manually
m ove parked w iper a rm s a s dam age to linkage or
m otor may occu r.
WIPER MOTOR AND LINKAGE
REPLACEMENT
MOTOR REPLACEMENT (F ig. 25)
1. Exhaust p r e ssu r e from a ir supply sy ste m
and then disconnect a ir supply lin e s at w iper m otor
in let p o rts.
2. D iscon n ect retain er clip attaching m otor
driver arm to w iper pivot a ssem b ly link.
3. R em ove four attaching b o lts secu rin g motor
bracket to front body inner panel. R em ove motor
and b racket a ssem b ly from under dash.
4. R e v erse rem oval procedure to in sta ll.
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL