The drum brake system in the 1984 Grand Marquis is a self-energizing servo design common in many Ford rear-wheel drive vehicles. This design allows the front brake shoe (also called the primary shoe) to follow the rotation of the drum and force the rear brake shoe (also called the secondary shoe) against the friction surface of the drum to slow the vehicle. A self-adjuster mechanism and parking brake function are integral to this system as well.
Tools Used: Wheel chocks, Floor jack, Jack stands, Lug wrench, Hammer, Brake tool set, Screw driver, Wire cutters
Assemble Drum Brake
Block the front wheels using wheel chocks. Raise and support the rear of the vehicle using a floor jack and jack stands positioned under the rear axles. Remove the rear wheels using a lug wrench and lay them aside.
Remove the brake drum from the brake assembly. The drums in the Grand Marquis slide off the hub and brake shoes. Use a hammer to apply a few sharp blows to the drum near the outer edge if the drum is stuck to the hub. This should unstick the drum so it can be slid off the shoes and hub.
Remove the brake shoe return springs front the anchor pin located above the wheel cylinder using a return spring tool to roll the springs off the anchor pin. Slip the parking brake bar located below the wheel cylinder from between the brake shoes.
Pull the lower edges of the brake shoes away from each other and allow the brake adjuster to drop out from between the two shoes. Push the lower edges of the shoes towards each other and unhook the lower spring from the adjuster lever. Remove the spring, adjuster lever and adjuster cable.
Remove the two hold down springs that attach the shoes to the brake backing plate using the hold down spring tool to rotate the retaining clips until they unlatch from the guide pin. Lay the primary shoe aside. Remove the u-clip that attaches the parking brake lever to the secondary shoe and slide the shoe off the lever. Lay the secondary shoe aside.
Clean the backing plate using a shop towel and lube the six raised contact points on the backing plate with a small dab of silicon grease. Install the secondary shoe (the larger of the two shoes) on the parking brake lever and secure it with the u-clip. Attach the secondary shoe to the backing plate using the hold down spring and hold down spring tool. Attach the primary shoe to the backing plate in the same manner.
Install the parking brake bar between the two shoes. Slip the adjuster cable onto the anchor pin and reinstall the return springs using the return spring tool to pry the springs onto the anchor pin.
Push the lower edges of the shoes towards each other. Slip the adjuster lever onto the primary shoe and clip latch the adjuster cable to it. Install the self adjuster spring on the secondary shoe and latch it to the adjuster lever. Pull out on the shoes and slip the adjuster into place between the them so that the star wheel of the adjuster is behind the adjuster lever.
Adjust the shoes to fit the drum by rolling the star wheel of the adjuster until the drum will just slide on. Remove the rubber plug from the back of the backing plate and use a bake spoon to turn the star wheel until a slight drag is felt from the shoes contacting the drum. Reinstall the rubber plug and the wheel. Repeat the process for the other side of the vehicle's brakes.
Tips & Warnings
Failure to support the vehicle weight with jack stands while working under it can result in vehicle damage and severe injury.
Wear safety glasses and work gloves to prevent serious injuries.
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