Checking front brake discs (wear assessment): General

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The condition of the parts can make replacement necessary under two criteria, depending on the wear of perforated brake discs:

Cracking in the holed (perforated) friction plate is in an advanced state.
Brake disc minimum thickness is not attained due to wear (material erosion due to friction).
In practice, both forms of disc erosion occur.

Usually, it is necessary to replace the brake discs when they fall short of the brake disc minimum thickness. Only in rare cases (for long-term race driving brake loads/very high temperature fluctuations in the friction surfaces), the cracking and perforating can proceed so quickly that a premature disc change has to be performed. Both criteria governing acceptable disc condition will be described separately in the following sections.