During a disc brake break-in, inspect all components except shoe thickness. A thorough brake inspection begins with a visual check of all parts. This includes hard lines, their connections to hoses (ensuring they’re pliable, not soft), calipers, and pads (for initial wear). Check for caliper damage, rotor scores, and intact ABS lines and sensors.
Next, consult manufacturer specifications for discard thickness on the rotor (replace if below minimum), refinishing thickness, DTV, and runout. Inspect pads; new Bosch pads are thick, while worn pads are thin. Use a pad measurement tool to confirm if pads are below minimum specifications (green for good, yellow for marginal, red for replacement).
When removing the caliper, always hang it with an S-hook or bungee cord to prevent damage to the brake hose. Use a proper tool to retract the piston, following manufacturer specifications (especially for electric calipers or built-in e-brakes). C-clamps can work, but always adhere to specifications.
For a professional brake job, lube all slides and ensure everything is clean. Follow manufacturer specifications for disassembling and reassembling components, as every car is different. Once caliper bolts are out, remove the caliper and suspend it. Push the piston back if needed. Perform another visual inspection, even checking suspension for torn boots.
Inspect pads for glazing, fluid, or grease; replace if present. Use a caliper retracting tool with a pad to protect the pistons. After retracting, visually inspect again. Install pads, reverse the procedure, and use correct torque specifications, especially for caliper brackets which may require Loctite.
While most rotors are replaced, they can be machined using a brake lathe. Follow manufacturer instructions for your specific rotor, ensuring a clean surface. On-car brake lathes are beneficial as they machine the wheel, hub, and bearing, reducing lateral runout or DTV.
Finally, follow the burn-in process for disc or drum brakes (e.g., 20 slowdowns from 50 mph to 20 mph with light to moderate pressure, 30 seconds between applications for cooling). This prevents damage and ensures proper material transfer to the rotor, avoiding DTV.
The initial question asks what not to inspect during a disc brake inspection: shoe thickness. Shoes are for drum brakes, not disc brakes. Understanding this helps pass the A-5 brake exam.
Brake Inspection and Service
