GMC C-SERIES 1999 Owners Manual

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6-33 Four-Wheel and Six-Wheel Drum Brakes
(Air Only)
The brake drums should be removed and inspected each
time the tires are removed for rotation or changing.
When you have the front brakes replaced, have the rear
brakes inspected, too.
Brake linings should always be replaced as complete
axle sets.
Brake Pedal Travel
See your dealer if the brake pedal does not return to
normal height, or if there is a rapid increase in pedal
travel. This could be a sign of brake trouble.
Brake Adjustment
Every time you make a brake stop, your brakes adjust
for wear.
Air Brake Systems (If Equipped)
If you have air brakes, it is important to get rid of
moisture in the system. Moisture will damage your
system if it isn't removed daily.There are two ways to do this. One is automatic if your
air
-brake vehicle has the optional moisture ejector. If
your vehicle doesn't have that option, however, you
must drain the air reservoirs every day.
Drain them at full system
pressure. To be sure you're
at full pressure, check
your air pressure gage.
It should read at least
100 psi (692 kPa).
Moisture Ejector (Option)
If you have air brakes with a moisture ejector, the valve
automatically ejects moisture from the reserve tank
when the air compressor cycles.
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6-34 Air Dryer (Option)
If your vehicle has air brakes, it may have an air dryer.
This collects and removes dirt, moisture or other foreign
matter from the air prior to entering the brake system. It
is mounted on the left frame rail.
If your dryer is a
Bendix
-Westinghouse, it
has a filter that you need to
change at intervals. See
your Maintenance Schedule
for more about servicing
this filter.
Alcohol Injector (Option)
If your vehicle has air brakes, it may have an alcohol
injector. It is on the frame or crossmember at the right
front corner of the vehicle.
The alcohol injector helps prevent moisture in the air
brake system from freezing. Use it only in cold weather,
32
F (0
C) or below.
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6-35
To turn it on in cold
weather, turn the valve so
that the word ON is on top.
When the temperature is
above freezing, turn the
valve to OFF.
During the cold weather season, you may find that you
need to check this bottle once a week.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. Your vehicle
was designed and tested with top
-quality GM brake
parts. When you replace parts of your braking
system
-- for example, when your brake linings wear
down and you have to have new ones put in
-- be sure
you get new approved GM replacement parts. If you
don't, your brakes may no longer work properly. For
example, if someone puts in brake linings that are wrong
for your vehicle, the balance between your front and
rear brakes can change
-- for the worse. The braking
performance you've come to expect can change in many
other ways if someone puts in the wrong replacement
brake parts.
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6-36
Electric/Hydraulic Parking
Brake Fluid
If you have an electric/hydraulic parking brake, a good
time to check the fluid level is when you check the fluid
levels under the hood.
If you need to add fluid, use Dexron III automatic
transmission fluid (GM Part Number 12345881).
How to Check and Add Fluid
First, apply the parking brake. To check the fluid level,
look at the MAX and MIN lines on the side of the
reservoir. If the level is below the MAX line, add fluid.
To add fluid, clean away any dirt around the reservoir
cap. Remove the reservoir cap and add enough fluid to
bring it up to the MAX level.
NOTICE:
Always use proper fluid (automatic transmission
fluid), not brake fluid. Failure to use the proper
fluid can cause leaks and damage hoses and seals.
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6-37 Clutch Pedal Free Travel
If you have a manual transmission, your clutch will need
adjustment when pedal free travel gets down to about
1 1/4 inch (32 mm), as measured at the clutch pedal pad.
You should have 1 1/2 to 2 inches (38 to 51 mm) of
clutch pedal free travel. Your Maintenance Schedule has
more on this.
If your clutch ever needs service, be sure to use only
genuine GM clutch replacement parts.
Chassis Lubrication
Your Maintenance Schedule provides all of the required
chassis lubrication intervals and identifies proper
lubricants to use. Be sure to see your Maintenance
Schedule before performing any chassis lubrication
service. To determine location of chassis lubrication
items, use the following charts.
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6-38
Single Axle Models
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6-39
ITEM NO. ITEM REMARKS
1 Brake Camshaft
, Brake Caliper
Rails (If Equipped)$One fitting each (apply sparingly). For caliper rails,
apply Aero Shell #5 Lubricant.
2 Steering Column Slip Joint* One fitting.
3 Steering Drag Link Ends One fitting at each end.
4 Steering Column U
-Joints One fitting each joint.
5 Pivot Points and Hinges Apply chassis lubricant.
6 Slack Adjuster
One fitting.
7 Brake Cam Roller Pins at interface
of pin and shoe
Apply engine oil.
8 Front Steering Knuckles One fitting each side, lower bushing (hand
-operated
grease gun only). Hand
-pack upper bearing.
9 Front Wheel Bearings Hand
-pack or lubricate.
10 Steering Tie Rod Ends One fitting each end.
11 Spring Slip Pads*
(Multi
-Leaf Only)Apply chassis lubricant.
12 Clutch Release Bearing* Cup or fitting.
13 Battery Terminal
(except ªSTº type)Keep coated with petroleum jelly.
14 Parking Brake Bell Crank*$ One fitting.
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6-40
ITEM NO. ITEM REMARKS
15 Transmission Fill to level of filler plug.
16 Transmission
-Auto*
Check fluid level.
17 Propshaft Slip Joint One fitting each joint; lubricate with GM Part
No. 1051344 Wheel Bearing Lubricant.
18 Propshaft U
-Joints One fitting each joint (1480 and 1550 Series); lubricate
with GM Part No. 1051344 Wheel Bearing Lubricant. Two
fittings each joint (1610 Series and larger); lubricate with
GM Part No. 1051344 Wheel Bearing Lubricant.
19 Rear Wheel Bearing Hand
-pack or lubricate.
20 Rear Axle Fill to level of filler plug.
21 Parking Brake Clevis Pin$ Apply chassis lubricant.
22 Master Cylinder $ Fill to 1/4, (6 mm) below opening.
23 Parking Brake Lever Pivot*$ Apply chassis lubricant.
* Applies to some vehicles.
 Applies to air brakes only.

Refer to Allison Transmission Operator's Manual.
$ Applies to hydraulic brakes only.
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6-41
Tandem Axle ModelsITEM
NO.ITEM REMARKS
1 Brake Camshafts One fitting each.
2 Propshaft U
-Joint One fitting each joint
(1480 and 1550 Series).
Lubricate with GM Part
No. 1051344, Wheel
Bearing Lubricant.
4 Brake Shoe
Roller PinsApply engine oil at pin
to shoe joint only.
5 Rear Spring Pin One fitting each side.
6 Wheel Bearings Hand
-pack or lubricate.
7 Rear Axles Fill to level of filler plug.
8 Propshaft Slip
JointTwo fittings each side.
Lubricate with GM Part
No. 1051344 Wheel
Bearing Lubricant.
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6-42
Battery
Your new vehicle comes with one or more ACDelco
Freedom
maintenance free batteries. When it's time
for a new battery, we recommend an ACDelco Freedom
maintenance free battery. Be sure it has the replacement
number shown on the original battery's label.
Vehicle Storage
If you're not going to drive your vehicle for 25 days or
more, remove the black, negative (
-) cable from the
battery. This will help keep your battery from running
down. (If your vehicle has more than one battery, be
sure to remove the negative (
-) battery cable from
each battery.)
CAUTION:
Batteries have acid that can burn you and gas
that can explode. You can be badly hurt if you
aren't careful. See ªJump Startingº in the Index
for tips on working around a battery without
getting hurt.
When you are ready to use the vehicle again, refer to the
engine starting procedure in the Index.
Contact your dealer to learn how to prepare your vehicle
for longer storage periods.
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