16Disc Brake Service - Caliper Caution! You can crush your finger when using compressed air to remove a caliper piston during rebuilding.
17Disc Brake Service - Caliper You should use only brake cleaner or brake fluid to clean brake caliper parts! Coating the brake caliper piston with brake fluid before installation helps to make reassembly go easier.
18Disc Brake Service - Caliper You should use a pointed hook tool to remove the caliper piston seal.
19Disc Brake Service – Disc/Rotor The two most important precision measurements that need to be made on a brake disc/rotor are the disc thickness and the disc runout .Measuring disc thicknessMeasuring disc runout
20Disc Brake Service – Disc/Rotor The minimum disc thickness is measured across the two friction surfaces in several different places.The maximum disc runout is the amount of side-to-side movement measured near the outer edge of the brake disc’s friction surface.Measuring disc thicknessMeasuring disc runout
21Disc Brake Service – Disc/Rotor The warpage or brake disc runout typically should not exceed 0.004”
22Disc Brake Service – Disc/Rotor Brake Lathe for machining Disc/Rotors off the vehicle
23Disc Brake Service – Disc/Rotor On-the-Car Brake Lathe for machining Disc/Rotors on the vehicle. (You don’t have to remove the disc to machine it!)
24Disc Brake Service – Disc/Rotor When machining a disc, you must do all the following:1. Measure the disc before machining2. Measure the disc after machining3. Document the measurements on the repair orderBrake discs should be inspected for all of the following defects:1. Hot Spots2. Cracks3. Warpage
25Drum Brake ServiceA typical Drum Brake Service includes these seven operations:Remove parts from the backing plateClean and inspect the partsReplace the brake shoesReplace or rebuild the wheel cylindersTurn the brake drumsLubricate and reassemble the brake partsPre-adjust, bleed, and test the brakes
26Drum Brake Service - Tools Drum Micrometer Brake Cylinder Hone Spring Depressor Pressure BleederMicrometer Bleeder Wrench Brake Spring Pliers Dial Indicator
27Drum Brake ServiceGently hammering on the brake drum can help loosen it.Springs on drum brakes can be different colors.Leaking wheel cylinders will affect brake operation.Working on drum brakes requires many special tools.When honing the wheel cylinder it is never a good idea to pull the hone out of the cylinder while it is spinning or you may cause damage to yourself, the hone, or the wheel cylinder!
29Drum Brake Service - Tips Some good methods of remembering how the rear drum brake parts go together: Taking a digital picture Taking only one side apart at a time Making a drawingIf a brake drum’s inside diameter is too big the drum must be replaced.The preparation of the brake drum’s inner surface is called machining, turning, or resurfacing
30Drum Brake Service - Tips Brake shoe linings are fastened to the brake shoe by rivets, glue, or both.Lubricating of the backing plate should be done with high temp grease, sparingly.Parking brakes should never be adjusted too tight.Parking brakes that are adjusted too tight can overheat, drag, or cause pulling.
31QUESTIONS?Check in the Duffy textbook Chapter 72