Q: How to inspect and maintain Brake Booster and brake system, including disc brakes, drum brakes, and the parking brake on Subaru Legacy?
A: In addition to specified intervals, brakes should be inspected every time the wheels are removed or when a defect is suspected. Symptoms indicating potential brake system defects include the vehicle pulling to one side when the brake pedal is pressed, squealing or dragging noises when brakes are applied, excessive brake pedal travel, pedal pulsations, or brake fluid leaks, usually onto the inside of the tire or wheel. To inspect disc brakes, loosen wheel lug nuts, raise the vehicle on jackstands, remove the wheels, and check pad thickness by inspecting through the caliper's inspection window. Replace pads if lining material is too thin. If uncertain, remove the caliper for further inspection. Clean and re-measure pads with brake cleaner. Measure disc thickness with a micrometer and inspect for damage. Before reinstalling wheels, check brake lines and hoses for damage, wear, leakage, and proper routing. For drum brakes, ensure the parking brake is off, remove the drums, and clean the brake assembly. Note lining thickness on brake shoes, replace if necessary, and check for cracks or glazing. Examine components for fluid leakage, and check the wheel cylinders for signs of leakage. Wipe the inside of the drum, inspect it for imperfections, and repeat the procedure for the other wheel. For the brake booster, perform a series of tests as described while seated in the driver's seat. If the brakes do not operate as described, the brake booster has failed. To check the parking brake, park the vehicle on a steep hill with the parking brake set and the transaxle in Neutral to ensure it can prevent the vehicle from rolling. Adjust the parking brake if necessary.