GMC 2010 T-Series Owner's Manual page 183

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 the front brakes are replaced, have the
rear brakes inspected, too.
Brake linings should always be replaced as complete
axle sets.
Brake Pedal Travel
See your dealer/retailer 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 that brake service
might be required.
Brake Adjustment
Every brake stop, the brakes adjust for wear.
Brake Adjustment on Air Braked Vehicles
The vehicle has automatic slack adjusters. Every brake
stop, the brakes automatically adjust for wear. Slack
adjusters should never be manually adjusted to correct
excessive brake chamber pushrod stroke. Excessive
brake chamber pushrod stroke means that the brake
system needs to be serviced by a qualified service
technician.
Notice: Do not manually adjust automatic slack
adjusters. Manual adjustment of the automatic slack
adjusters can result in a degradation of the slack
adjuster performance over time. If the brake
chamber pushrod stroke is out of adjustment, the
brake system needs to be serviced by a qualified
service technician.
Four-Wheel Disc Brakes
(Hydraulic Only)
The vehicle has four-wheel disc brakes.
Some driving conditions or climates can cause a brake
squeal when the brakes are first applied or lightly
applied. This does not mean something is wrong with
the brakes.
Brake linings should always be replaced as complete
axle sets.
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