GMC 1997 Safari Owner's Manual page 291

Properly torqued wheel nuts are necessary to help
prevent brake pulsation. When tires are rotated, inspect
brake pads for wear and evenly torque wheel nuts in the
proper sequence to GM specifications.
Your rear drum brakes don't have wear indicators, but if
you ever hear a rear brake rubbing noise, have the rear
brake linings inspected. Also, the rear 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.
See "Brake System Inspection'' in Section 7 of this
manual under Part C "Periodic Maintenance
Inspections."
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 disc brakes
adjust for wear.
If your brake pedal goes down farther than normal, your
rear drum brakes may need adjustment. Adjust them by
backing up and firmly applying the brakes a few times.
Replacing Brake System Parts
The braking system on a modern 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.