Chevrolet DB90 Series, Руководство по обслуживанию

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SECTION 5
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A ll inform ation in 1970 Heavy Duty Truck S ervice Manual ST 135-70 BRAKES
(SEC. 5) a lso applies to v e h ic le s covered by this supplem ent except a s sp e c ific a lly
stated in the follow ing procedures:
SECTION 5A
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BRAKE SYSTEM MAINTENANCE
R efer to 1970 Heavy Duty Truck S erv ice
Manual ST135-70, page 5-1 under above heading.
The statem en t in Step 1 — “ At le a st once a year,
drain and flush en tire brake sy ste m and r e fill with
new fluid” no longer applies.
Flushing sy ste m and replacing fluid is n e c e s ­
sary only when it is known or su sp ected that s y s ­
tem has becom e contam inated with dirt, w ater,
wrong type fluid, etc .
CLEANING AND FLUSHING
BRAKE PARTS AND SYSTEM
Under the headings of "Bleeding B rak es,"
"M aster Cylinder O verhaul," and "Wheel C ylinder
R epair” in 1970 Heavy Duty Truck S erv ice Manual
ST135-70 in stru ction s are given to wash or clean
p arts with DENATURED ALCOHOL.
L atest in stru ction s sp e c ific a lly state "DO NOT
USE ALCOHOL" fo r flushing hydraulic brake s y s ­
te m s or for w ashing p a rts with internal p a ssa g e s
in which fluid could be trapped. The only approved
fluid for such cleaning or flushing operations is
new brake fluid. P a r ts without internal p a ssa g e s
may be cleaned with alcohol but must be com ­
p letely dried and coated with brake fluid b efore
a ssem b ly .
CAUTIO N : DO NOT use kerosene,
gasoline, or other unapproved solvents
for cleaning o r flushing hydraulic
brake
system s or parts.________________________________
BRAKE PEDAL PUSH ROD
ADJUSTMENT
IMPORTANT: If any doubt e x ists rela tiv e to
push rod adjustm ent, rem em b er it is b etter to
have push rod too short than for it to be too long.
"H" AND "J” MODELS
1. L oosen lock nut on brake pedal push rod
and shorten push rod until brake pedal is com pletely
clea r of brake pedal bumper stop.
2. P la c e a 0.0 4 0 -in ch sh im between brake
pedal and brake pedal bumper stop.
3. With m aster cylinder properly in sta lled on
fir e w all and m aster cylinder p iston in rearm ost
p osition against retaining ring, adjust push rod
length until push rod contacts m aster cylinder
piston.
4. Hold push rod firm ly and tighten lock nut.
5. Check operation of b rak es.
TILT CAB MODELS
1. Set em ergency brake or block w h eels.
2. T ilt cab (se e in stru ction s).
3. To adjust, lo o sen adjusting nut and turn rod
in or out of rod end as n e c e ssa r y . Adjust so that
th ere is 1/8" free play m ovem ent of brake pedal
at pad before end of push rod contacts piston.
4. Tighten adjusting nut.
5. Check operation of b rakes.
MASTER CYLINDER REPLACEMENT
CONVENTIONAL MODELS
R em oval
1. P la ce a suitable container under m aster
cylinder to catch fluid when hydraulic lin e is d is ­
connected. DO NOT RE-USE THIS FLUID.
2. D isconnect hydraulic line from outlet.
3. R em ove two b olts and lock w a sh ers attach­
ing m aster cylinder to fir e w all (nuts a re w elded
to inner side) and rem ove m aster cylinder a s ­
sem b ly.
Installation
1. P la c e m a ster cylinder in p osition on fir e
w a ll. Make certain push rod i s aligned properly and
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL SUPPLEMENT