What tool should be used to check for rotor thickness variation?

To check for rotor thickness variation, the most appropriate tool to use is a dial indicator. A dial indicator is specifically designed to measure small distances and variations with precision. When testing brake rotors, it can detect any unevenness or variations in thickness that may affect braking performance. The dial indicator allows the technician to assess even slight discrepancies in rotor thickness while the rotor is rotating, making it ideal for ensuring that the rotors are within the acceptable tolerance levels for safe operation.

While a micrometer can measure rotor thickness, it is primarily designed for measuring small dimensions rather than detecting variations across the entire surface of the rotor. A caliper gauge and a vernier scale can also provide measurements but are less effective than a dial indicator for capturing the specific variations that could lead to issues such as pulsation or vibration during braking. Therefore, the dial indicator stands out as the best tool for accurately checking rotor thickness variation.