Answer :
Before measuring lateral runout on a brake rotor, you must perform the important step of cleaning the brake rotor and hub/axle flange mating surface. Therefore, the correct answer to the multiple-choice question is: C. Clean the brake rotor and hub/axle flange mating surface.
Detailed Explanation:
What is Lateral Runout?
Lateral runout refers to the amount of 'wobble' a brake rotor has as it rotates. It is an important measurement because excessive runout can cause vibrations and lead to uneven wear on the brake pads, ultimately affecting the vehicle's braking performance.Why Clean the Surfaces?
Cleaning the rotor and the hub/axle flange mating surface is crucial because dirt, rust, or debris on these surfaces can create an uneven platform for the rotor to sit on. This unevenness alters the rotor's position slightly, leading to inaccurate measurements of lateral runout.How to Clean the Surfaces:
- Ensure the vehicle is safely lifted and supported.
- Remove the wheel to access the brake rotor and hub.
- Use a wire brush or appropriate cleaning tool to scrub away any rust or debris from the rotor and hub/axle flange.
- In some cases, a brake cleaner spray may also be used to remove stubborn dirt.
After Cleaning:
Once the surfaces are clean, you can proceed to measure the lateral runout. Attach a dial indicator to a stable part of the suspension or hub, set the gauge against the rotor surface, and rotate the rotor. The dial indicator will show you any deviations, which indicates the runout.
By following these steps, you ensure that your brake system is functioning safely and effectively.
