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Replacing Brake System Parts
The braking system on a vehicle is complex. Its many
parts have to be of top quality and work well together if
the vehicle is to have really good braking. The vehicle
was designed and tested with top-quality brake parts.
When parts of the braking system are replaced — for
example, when the brake linings wear down and new
ones are installed — be sure to get new approved
replacement parts. If this is not done, the brakes might
not work properly. For example, if someone puts in brake
linings that are wrong for the vehicle, the balance
between the front and rear brakes can change — for the
worse. The braking performance expected can change in
many other ways if the wrong replacement brake parts
are installed.
Hydraulic Brake Pads
Brake pad lining life will vary depending on
vehicle application, working environment, equipment
maintenance, and style of driving. The brake pad lining
wear rate has to be monitored for individual driving
habits — original equipment linings have mechanical
wear indicators to help with this. When down to the last
10% of the brake lining, the brake lining wear indicator
rubs on the rotor, causing a scratching or chirping
sound. When this sound is heard, service to the brake
pads is needed. SeeScheduled Maintenance on
page 6-5.
Aftermarket brake linings might not meet the same
stringent requirements as the original equipment linings.
Using aftermarket brake linings can affect braking
performance, pedal feel, noise, and lining wear.
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Air Brake Systems
If the vehicle has air brakes, it is important to get rid of
moisture in the system. Moisture will damage the system
if it is not removed daily.
There are two ways to do this. One is automatic through
the air brake vehicle’s air dryer with integral automatic
moisture ejector that purges air from the system through
a self-contained reservoir. The other way to drain
moisture from the air brake system is to manually activate
drain valves at each reservoir. Drain the air reservoirs
occasionally to be sure the air dryer is working properly.
Drain the air brakes at full system pressure. To be sure of
full pressure, check the air pressure gage. It should read
at least 100 psi (692 kPa).
Air Dryer
If the vehicle has air brakes, it has an air dryer mounted
on the passenger side frame rail. This collects and
removes dirt, moisture, or other foreign matter from the
air prior to entering the brake system. The dryer also
acts as a moisture ejector. It automatically ejects
the moisture when the compressor cycles. The purge
tank has a manual drain valve that must be drained
every day. See “Air Brake Systems” for the manual drain
procedure.
The dryer has a filter that needs changing at intervals.
SeeScheduled Maintenance on page 6-5for more about
servicing this filter.
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Electric Air Compressor
The vehicle might have an electric air compressor.
This compressor is used to run options that require
pressurized air, such as an air horn or air seat.
The air compressor is used when vehicles do not have
an air brake system.
The air supply for this
system must be
maintained by releasing
the drain valve to eject any
moisture that could have
built up in the system.
It is recommended that this system be drained on a
weekly basis.
Clutch Pedal Free Travel
If the vehicle has a V8 engine and a manual
transmission, the clutch needs adjustment when pedal
free travel gets down to about 1/4 inch (6 mm), as
measured at the clutch pedal pad. There should be
1 1/2 to 2 inches (38 to 51 mm) of clutch pedal
free travel.
If the clutch ever needs service, be sure to use only
approved clutch replacement parts.
Chassis Lubrication
The Maintenance Schedule provides all of the required
chassis lubrication intervals and identifies proper
lubricants to use. Be sure to see the Maintenance
Schedule before performing any chassis lubrication
service. To determine location of chassis lubrication
items, use the following charts.
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Single Axle Models
Item Number Item Remarks
1 Brake Camshaft** One fitting each (apply sparingly).
2 Steering Column Slip Joint* One fitting.
3 Steering Drag Link Ends One fitting each end.
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Item Number Item Remarks
4 Pivot Points and Hinges Apply chassis lubricant.
5 Pivot Points and Hinges Apply chassis lubricant.
6 Slack Adjuster** One fitting.
7Brake Cam Roller Pins at interface of pin
and shoe**Apply engine oil.
8 Front Steering KnucklesOne fitting each side, lower bushing.
(Hand-operated grease gun only.) Hand-pack upper
bearing.
9 Front Wheel Bearings Hand-pack or lubricate.
10 Steering Tie Rod Ends One fitting each end.
11 Spring Slip Pads* (Multi-Leaf Only) Apply chassis lubricant.
12 Clutch Release Bearing* Cup or fitting.
13 Battery Terminal (except “ST” type) Keep coated with petroleum jelly.
14 Transmission Fill to level of filler plug.
15 Propshaft U-JointsLubricate with GM Part No. 1051344 Wheel Bearing
Lubricant.
16 Parking Brake Clevis Pin$ Apply chassis lubricant.
17 Parking Brake Lever Pivot*, $ Apply chassis lubricant.
18Clutch Release Cross Shaft, Master
Cylinder$Apply chassis lubricant, fill to 1/4 inch (6 mm) below
opening.
19 Release Bearing, Clutch Cross Shaft Two fittings, apply chassis lubricant.
20 Clutch Release Fork Two fittings.
* Applies to some vehicles.
** Applies to air brakes only.
$ Applies to hydraulic brakes only.
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Tandem Axle ModelsItem
Number Item Remarks
1 Brake Camshafts One fitting each.
2 Propshaft U-JointOne fitting
each joint.
Lubricate with GM
Part No. 1051344,
Wheel Bearing
Lubricant.
3 Rear AxlesFill to level of
filler plug.
4Brake Shoe
Roller PinsApply engine oil
at pin to shoe
joint only.
5 Rear Spring PinOne fitting
each side.
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Battery
This vehicle has two or more maintenance free batteries.
When it is time for a new battery, see your dealer/retailer
for one that has the replacement number shown on
the original battery’s label.
Warning:Battery posts, terminals, and related
accessories contain lead and lead compounds,
chemicals known to the State of California to cause
cancer and reproductive harm. Wash hands after
handling.
Vehicle Storage
{CAUTION:
Batteries have acid that can burn you and gas that
can explode. You can be badly hurt if you are not
careful. SeeJump Starting on page 5-62for tips
on working around a battery without getting hurt.
Infrequent Usage: If the vehicleis driven infrequently,
remove the black, negative (−) cable from each battery.
This helps keep the batteries from running down.
Extended Storage: For extended storage of the vehicle,
remove the black, negative (−) cable from each battery or
use a battery trickle charger. This helps maintain the
charge of the batteries over an extended period of time.
When ready to use the vehicle again, refer to the engine
starting procedure in the Index.
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Jump Starting
If the vehicle’s battery (or batteries) has run down, you
may want to use another vehicle and some jumper
cables to start your vehicle. Be sure to use the following
steps to do it safely.
{CAUTION:
Batteries can hurt you. They can be dangerous
because:
•They contain acid that can burn you.
•They contain gas that can explode or ignite.
•They contain enough electricity to burn you.
If you do not follow these steps exactly, some or
all of these things can hurt you.Notice:Ignoring these steps could result in costly
damage to the vehicle that would not be covered
by the warranty.
Trying to start the vehicle by pushing or pulling it
will not work, and it could damage the vehicle.
1. Check the other vehicle. It must have a 12-volt
battery (or batteries) with a negative ground
system.
Notice:If the other vehicle’s system is not a 12-volt
system with a negative ground, both vehicles can
be damaged. Only use vehicles with 12-volt systems
with negative grounds to jump start your vehicle.
If you have a diesel engine vehicle with two batteries
(or more), you should know before you begin that,
especially in cold weather, you may not be able to get
enough power from a single battery in another
vehicle to start your diesel engine.
If your vehicle has more than one battery, use the
one closest to the starter — this will reduce electrical
resistance.
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