Front brake disc — inspection and regrinding (Honda Accord 3)

Inspection

1. The brake disc gets circular scratches when braking due to the capture of dust and road sand. Excessive scratching not only creates a squealing brake, but also shortens the service life of the brake pads. However, slight damage to the disc surface, not exceeding 0.38 mm in depth, also occurs during normal operation. It is not dangerous when braking. If the grooves are deep enough to catch a fingernail, then appropriate measures must be taken.

Differences between the left and right surfaces of the disc may result in uneven braking.

2. Disc runout occurs when the disc moves from side to side, warps, or deforms. Excessive runout causes wobble or knocking in the brake pedal. Place a dial indicator on the center of the worn surface of the pad and rotate the disc, watching the readings. If the disc runout exceeds 0.10 mm, replace or regrind the disc.

3. The parallelism of the disc is checked by measuring the thickness of the disc at different positions around the disc's circumference. To check the parallelism of the disc, place a mark on the disc and measure the thickness of the disc with a micrometer. Repeat this measurement eight times, moving around the disc's circumference (each time by approximately 45 degrees). If the measurements change by more than 0.015 mm, replace the disc.

Regrinding

Brake discs can be restored subject to mandatory compliance with the following rules:

Nowhere should the disc be thinner than the minimum thickness. (The limits are specified in Specifications for Brakes in this Chapter). The difference between the thickness of a new disc and the absolute limit is usually very small; if the disc has been used for several years, it is already close to the limit, and regrinding will not be able to eliminate the defects without going beyond the wear limits. It is always better to replace the disc.
If the disc is reground, the procedure must be performed on an automotive lathe.
Always replace the brake pads at the same time as installing new or resurfacing old discs.