The rear brakes on a Buick Park Avenue are drum brakes connected to the parking brake. If the parking brake offers little resistance when you apply it, you need to fix the rear brakes. You might just need to adjust the positioning of the brake shoes to get them working again. In most cases, though, you need to replace the shoes. This will involve working with the many springs and levers within the drum assembly.
Block the front wheels with wheel chocks.
Raise the car's rear end with a jack and support it on jack stands.
Remove the lug nuts on the rear wheels with a tire iron then remove the wheels.
Remove the plug in the top end of the brake drum with a hammer and chisel.
Insert a hooked tool into the hole in the drum and turn the star wheel until the brake shoes drag against the drum when you turn it.
Turn the adjuster screw in the opposite direction to back off of it until the shoes just reach the point where the drum turns freely again.
Pull the brake drum off the brake assembly.
Unhook and remove the top return spring with a pair of needle-nose pliers, then unscrew and remove the hold-down pins for the shoes with a special spring removal tool.
Pull the front brake shoe down and detach it from the lower return spring. Pull out the adjuster rod, then pull down the rear spring, remove the clip for the parking brake lever and press out the lever's pin.
Remove the actuator spring, its connecting link and actuator from the old front shoe and install them on the replacement shoe.
Lubricate the raised spots on the brake backing plate with high-temperature lithium grease.
Connect the replacement rear shoe to the parking brake lever, pushing its pin into the hole, then installing its spring washer and installing the clip with pliers -- the washer's concave side must face the lever.
Lubricate the adjuster's threads, socket face and inside surface with the grease.
Place the new brake shoes onto the backing plate, connect them with the lower return spring and fasten them with the hold-down springs. Lubricate the adjuster screw and install the adjuster rod so it seats against the parking brake lever and the front shoe's actuator.
Install the upper return spring with the pliers, making sure the spring's rear end goes through the rear shoe and parking brake lever and the front hook goes onto the front shoe's actuator connecting link
Slide the brake drum onto the brake assembly and adjust the brakes as described in Section 2.
Remount the wheels and lower the car off the jack stands with the jack. Tighten the lug nuts with the tire tool.
