BRAKES
5 -4 9
PRELIMINARY CHECKS
External Conditions That Affect Performance
In addition to previously mentioned conditions, the
following external conditions may affect brake perform
ance and should be corrected before work is done on the
brake mechanism.
Tires
Tires having unequal contact and grip on the road could
cause unequal braking. Tires should be equally inflated
and tread pattern of right and left tires should be
approximately equal.
Loading
When the vehicle has unequal loading, the most heavily loaded
wheels require more braking power than others.
Shock Absorbers
Faulty shock absorbers that permit bouncing of the vehicle on
quick stops may give the erroneous impression that brakes are
too severe.
General Checks
NOTE: If a damaged component or malfunc
tion is discovered while making any of the
following brake system checks, repairs must
be made before attempting to continue with
additional diagnosis.
1. Inspect for excessive tire tread wear and indications
of front suspension misalignment. Check tire
pressures and for improperly adjusted or worn
wheel bearings. Any of these conditions can result
in an improper diagnosis.
2. Check master cylinder fluid level. If low, refill to the
proper level, pressurize the system, and make an
inspection of the entire brake system for leakage.
Wheel cylinder leakage can frequently be detected
by the presence of brake fluid on the inboard side
of the wheel and tire.
3. Power Brake:
a. With transmission in Park, stop the engine, and
exhaust all vacuum in the system by depressing
the pedal several times.
b. Depress the brake pedal and hold it in the apply
position for one minute with approximately
20
lbs. pedal force. If the pedal gradually falls
away or the brake warning light comes on, it is
an indication that the hydraulic system is
leaking or that there is a malfunction in the
master cylinder. Check all tubing, hoses, wheel
cylinders, calipers and connections for leakage
before replacing the master cylinder.
c. If the brake pedal feels spongy, it is an
indication of air in the hydraulic system. Bleed
the air from the system and recheck the pedal
feel.
NOTE: Steps (b) and (c) may also be used to
check for leakage or the presence of air in a
non-vacuum powered brake system.
d. Depress the brake pedal and start the engine. If
the vacuum system is operating, the brake pedal
will tend to fall away when the engine starts and
less pedal pressure will be needed to hold it in
the applied position. If no action is felt when
the engine starts, the vacuum system is
inoperative.
ROAD TESTING
CAUTION:
A road test should be made only
when the operator is sure that the brakes will
stop the vehicle.
Road tests are necessary to check brakes for safe, quiet
performance. Preliminary inspection should be made in
the shop as outlined in the preceding paragraphs. The
following tests will aid in the evaluation of brake
performance and the need for service. They should be
conducted on dry, clean, reasonably smooth and level
roadway. Use care not to induce fade unintentionally
with continuous applications during test. Refer to the
Troubleshooting Chart for causes and remedies for
trouble which may be discovered during testing.
WARNING:
Before driving any vehicle, push
the brake pedal to make sure it will not
bottom. Next, make a series of slow speed
stops to determine if the brakes are safe for
driving.
Low Speed Test for Effectiveness, Pulls and
Noise
fk
S .
Make light and medium stops at from 10 to 15 MPH.
Bring the vehicle to a complete stop each time. Observe
the effort required to make each stop. Is it too light
(grabby) satisfactory or too hard? Check for pulls.
Unequal front brakes will cause pulls in the direction of
the brake doing the most work. Unequal rear brakes may
not cause noticeable pulling during low speed stops.
Check for noise. Open the windows and turn off all
accessories and listen to determine the type of noise and
the wheel from which it is coming.
NOTE: Driving along a wall when applying
brakes will make noises more audible.
High Speed Test for Roughness or
Pulsations
Make light stops from 60 MPH or maximum legal speed.
Check for roughness or pulsations by pedal feel and
vehicle vibration.
High Speed Test for Effectiveness, Pulls and
Noise
Make hard stops (just short of skid) from 60 MPH. Bring
LIGHT DUTY TRUCK SERVICE MANUAL
Содержание Light Duty Truck 1973
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Страница 39: ...HEATER AND AIR CONDITIONING 1A 13 Fig 14 Heater Wiring Diagrams LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 53: ...HEATER AND AIR CONDITIONING 1A 27 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 115: ...LIGHT DUTY TRUCK SERVICE M A N U A L HEATER AND AIR CONDITIONING 1A 89...
Страница 123: ...BODY 1B 3 Fig 6 Typical 06 Van LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 149: ...BODY 1B 29 Fig 84 Body Mounting 06 Fig 85 Body Mounting 14 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 171: ...LIGHT DUTY TRUCK SERVICE M A N U A L Fig 2 Frame Horizontal Checking Typical FRAME 2 3...
Страница 173: ...LIGHT DUTY TRUCK SERVICE M A N U A L Fig 4 10 30 Series Truck Frame FRAME 2 5...
Страница 174: ...2 6 FRAME LIGHT DUTY TRUCK SERVICE MANUAL Fig 5 Underbody Reference Points G Van...
Страница 177: ...LIGHT DUTY TRUCK SERVICE MANUAL G 10 20 C 10 P 10 30 Fig 2 Front Suspension C P K Typical FRONT SUSPENSION 3 3...
Страница 185: ...FRONT SUSPENSION 3 11 Fig 16 Toe out on Turns LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 229: ...REAR SUSPENSION AND DRIVELINE 4 5 Fig 13 Rear Spring Installation C K Models LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 310: ...5 44 BRAKES C MODELS G MODELS P MODELS Fig 77 Parking Brake System LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 351: ...ENGINE 6 15 Fig ID Sectional View of Eight Cylinder Engine LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 376: ...6 4 0 ENGINE LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 377: ...ENG IN E 6 41 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 378: ...LIGHT DUTY TRUCK SERVICE MANUAL Fig 37L K Series Engine Front Mount 6 42 ENG INE...
Страница 379: ...E N G IN E 6 43 FRONT MOUNT REAR MOUNT Fig 38L G Series Engine Mounts LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 400: ...6 6 4 ENG INE LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 401: ...ENG IN E 6 65 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 402: ...6 6 6 ENGINE LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 403: ...E NG IN E 6 67 Fig 36V C Series Engine Mounts LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 423: ...EN G IN E C OOLING 6K 13 Fig 16 Overheating Chart LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 424: ...6 K 1 4 ENG INE COOLING Fig 17 Coolant Loss Chart LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 455: ...ENGINE FUEL 6M 31 Fig K13 Accelerator Controls P30 42 454 Engine LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 456: ...6M 32 ENGINE FUEL Fig K15 Accelerator Controls G Van L 6 LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 506: ...CEC PLUNGER IS EXTENDED Fig lid Vacuum Advance Diagram Six Cylinder Engine 6T 14 EMISSION CONTROL SYSTEMS...
Страница 512: ...Fig 18e Vacuum Advance Diagram V8 Engine...
Страница 515: ...EMISSION CONTROL SYSTEMS 6T 23 Fig If Six Cylinder A I R System LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 516: ...6 T 2 4 E M IS S IO N CONTROL SYSTEMS LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 517: ...E M IS S IO N C O N TR O L SYSTEM S 6T 25 Fig 4f Diverter Valve Vent Valve LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 540: ...6 Y 1 2 ENGINE ELECTRICAL Fig 16b Battery Installation C K Series LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 592: ...7M 2 CLUTCHES MANUAL TRANSMISSIONS VIEW B Fig la Clutch Linkage Assy C K Models LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 593: ...CLUTCHES MANUAL TRANSMISSIONS 7M 3 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 594: ...7M 4 CLUTCHES MANUAL TRANSMISSIONS Fig lc Clutch Linkage Assy P Models LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 739: ...FUEL TANKS AND EXHAUST 8 9 Fig 15 Filler Neck and Vent Hose Van LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 740: ...8 10 FUEL TANKS AND EXHAUST Fig 16 Fuel Feed and Return Pipes Front C K LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 744: ...8 14 FUEL TANKS AND EXHAUST LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 746: ...8 16 FUEL TANKS AND EXHAUST Fig 2 5 Fuel Feed Pipe Front P 105 4 2 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 760: ...8 30 FUEL TANKS AND EXHAUST Fig 40 Exhaust Pipe P Models LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 781: ...STEERING 9 15 OIL PRESSURE OIL RETURN PORT VALVE BODY Fig 21 Left Turn Position LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 832: ...LIGHT DUTY TRUCK SERVICE MANUAL Fig 106 Power Steering Pump Mounting Typical 9 66 STEERING...
Страница 833: ...PUMP ASSEMBLY STEERING GEAR TYPICAL SMALL V8 TYPICAL LARGE V8 STEERING 9 67...
Страница 860: ...9 94 STEERING LEAKAGE AREAS Fig 133 Power Steering Gear Leakage LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 861: ...STEERING 9 95 Fig 134 Power Steering Pump Leakage LIGHT DUTY TRUCK SERVICE MANUAL...
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Страница 886: ...11 10 CHASSIS SHEET METAL LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 891: ...ELECTRICAL BODY AND CHASSIS 12 5 LIGHT DUTY TRUCK SERVICE MANUAL...
Страница 897: ...ELECTRICAL BODY AND CHASSIS 12 11 Fig 14 Instrum ent Cluster Assembly C K Models LIGHT DUTY TRUCK SERVICE MANUAL...
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