Inspection

Rear Wheel Cylinders

Wheel cylinders should not be disassembled unless they are leaking. Carefully pull lower edges of wheel cylinder boots away from cylinders to see if the interior of the cylinder is wet with brake fluid. Excessive fluid at this point indicates leakage past piston cups and a need for wheel cylinder overhaul.

NOTE: A slight amount of fluid is nearly always present and acts as a lubricant for the piston. It is not necessary to remove the brake cylinder from the backing plate to disassemble, inspect, hone and overhaul the cylinder. Removal is necessary only if the cylinder is damaged or scored beyond service.

Brake Drums

Minor scores on a brake drum (1126) can be removed with sandpaper. Do not refinish brake drums to remove score marks. A drum surface which is highly polished can cause the brake to lock up. This polished condition should be removed either with sandpaper or by refinishing the drum. A brake drum that is out of round sufficiently enough to cause vehicle vibration or noise when braking should be refinished. Remove only enough stock to true-up the brake drum. Brake drum maximum inside diameter is shown on each brake drum. If the maximum inside diameter shown on the brake drum is exceeded either through wear or refinishing, the brake drum must be replaced.

Check the inside diameter of the brake drum with Brake Adjustment Gauge D81L-1103-A or Rotunda Brake Drum Micrometer 104-00046 or equivalent.

After a brake drum is refinished, wipe the refinished surface with a cloth soaked in clean denatured alcohol. If one brake drum is refinished, the opposite brake drum on the same axle should also be refinished to the same diameter.

Adjuster

Check the action of brake adjuster screw (2041) by pulling brake shoe adjusting lever cable (2A178) toward secondary rear brake shoe and lining (2200), activating brake shoe adjusting lever (2A176). Brake shoe adjusting lever should snap in behind the next tooth of brake adjuster screw. Release brake shoe adjusting lever cable to return brake shoe adjusting lever to original position and the brake adjuster screw should turn one notch.

If pulling the brake shoe adjusting lever cable does not produce the action described, or if lever action is sluggish instead of positive and sharp, check the position of the lever on the adjusting screw toothed wheel. With the brake in a vertical position (anchor at the top), the lever should contact the adjusting wheel one tooth above the centerline of the adjusting screw. If the contact point is below this centerline, the lever will not lock on the teeth in the adjusting screw wheel, and the screw will not be turned as the lever is actuated by the cable.

Brake Lining

Brake linings that are worn to within 0.8mm (1/32 inch) of a rivet head or 1.5mm (1/16 inch) of the shoe on bonded linings or have been contaminated with brake fluid, grease or oil must be replaced. Failure to replace worn linings will result in a scored drum. When it is necessary to replace linings, they must also be replaced on the wheel on the opposite side of the vehicle.

NOTE: Whenever rear brake linings are removed, the parking brake cable tension should be checked.

Springs

Check condition of brake shoes, brake shoe retracting spring (2296) brake shoe hold-down springs (2068) and drum for signs of overheating. If shoes have a slight blue coloring indicating overheating, brake shoe retracting spring andbrake shoe hold-down springs should be replaced. Overheated springs lose their tension and could allow new lining to drag and wear prematurely, if not replaced.

Brake Backing Plate

Clean the ledge pads on the brake backing plate (2211). Sand lightly to bare metal.

Apply Silicone Dielectric Compound D7AZ-19A331-A or equivalent meeting Ford Specification ESE-M1C171-A at the points where the rear brake shoe and lining touch the brake backing plate.