Ford Aerostar 1986-1997 Repair Guide

Brake Drums


Brake shoes may contain asbestos, which has been determined to be a cancer causing agent. Never clean the brake surfaces with compressed air! Avoid inhaling any dust from any brake surface! When cleaning brake surfaces, use a commercially available brake cleaning fluid.


  1. Block both front wheels so that the vehicle will not roll when raised.
  3. Raise and support the rear of the van safely on jackstands.
  5. Remove the rear wheel(s).
  7. Remove the 3 retaining nuts, then pull the brake drum off of the lug studs. It may be necessary to back off the brake shoe adjustment in order to remove the brake drum. This is may be necessary since the brake drum may be grooved or worn from being in service for an extended period of time.

To install:
  1. Before installing a new brake drum, be sure to remove any protective coating with carburetor degreaser.
  3. Slide the brake drum onto the lug studs, then adjust the brakes as described earlier in this section.
  5. Install the rear wheel(s).
  7. Lower the vehicle.
  9. Remove the wheel blocks.


After the brake drum has been removed from the vehicle, it should be inspected for runout, severe scoring, cracks, and the proper inside diameter.

Minor scores on a brake drum can be removed with fine emery cloth, provided that all grit is removed from the drum before it is installed on the vehicle.

A badly scored, rough, or out-of-round (runout) drum can be ground or turned on a brake drum lathe. Do not remove any more material from the drum than is necessary to provide a smooth surface for the brake shoe to contact. The maximum diameter of the braking surface is shown on the inside of each brake drum. Brake drums that exceed the maximum braking surface diameter shown on the brake drum, either through wear or refinishing, must be replaced, since the drum loses its ability to dissipate heat, created by the friction between the brake drum and brake shoes, when the outside wall of the brake drum reaches a certain thickness (thinner than the original thickness). Also the brake drum will have more tendency to warp and/or crack.

The maximum braking surface diameter specification, which is shown on each drum, allows for a 0.060 in. (1.5mm) machining or cut over the original nominal drum diameter plus 0.030 in. (0.8mm) additional wear before reaching the diameter at which the drum must be discarded. Use a brake drum micrometer to measure the inside diameter of the brake drums.