Initial Inspection and Diagnostic Overview
DISASSEMBLY1. Raise and support vehicle.
2. Remove wheel and tire assembly from rear hub.
3. Remove retainers and brake drum from rear hub.
4. Use an industrial vacuum cleaner brake washer to remove all dust from rear brake backing plate and interior of the brake drums.
DRUM DIAMETER
NOTE: Best shop practice requires measuring every brake drum with a drum micrometer regardless of visual inspection. The drum micrometer is set to the drum diameter and measures the amount and type of wear.
CAUTION: If the braking surface diameter has worn in excess of the maximum diameter replace the brake drum.
^ Before making an inspection or measurement, remove grease, brake fluid, and other contaminants from the brake drum using denatured alcohol.
^ Check drum a diameter using drum micrometer to determine if brake drum braking surface diameter is less than 204.2mm (8.040 inch). If braking surface diameter exceeds specification, replace drum.
^ Measure the diameter at various points 45 degrees around the circumference, and at the bottom of the deepest groove to determine if the brake drum requires replacement.
Maximum Diameter Location:
^ The maximum drum specification is also cast into the drum.
DRUM OUT-OF-ROUND - A brake drum that is out-of-round can cause vehicle vibration and brake pedal pulsation when braking.
^ Measure the inside diameter of the brake drum using brake drum micrometer. Measure at several points around the inside of the brake drum.
^ Subtract the lowest reading from the highest.
^ To service an out-of-round condition refinish the brake drum.
BRAKE SHOES AND LININGS
^. Inspect brake shoes and linings for excessive lining wear, contamination or shoe damage. If lining is damaged or worn within 0.794 mm (1/32 inch) of the rivet heads on riveted linings or within 3.0 mm (0.125 inch) of the shoe on bonded linings, they must be replaced. Replace any brake shoe and lining that has been contaminated with oil, grease or brake fluid. Replace brake shoes and linings in axle sets.
^ Check condition of brake shoes and linings, brake shoe retracting springs and brake drum for signs of overheating. If brake shoes and linings have a slight blue coloring, indicating overheating, retracting and brake shoe hold-down springs should be replaced. Overheated springs lose their tension and could cause new lining to wear prematurely if they are not replaced. If brake drums are heat-spotted, indicating an overheated condition, they should be replaced.
REASSEMBLY
1. Install wheel and tire assemblies on vehicle. Tighten lug nuts to 85 Nm (62 ft. lbs.).
2. Lower and retest vehicle.