Check the brake disc
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Check brake disc friction surfaces.
If the brake disc displays signs of out-of-true, check its lateral run out. See Brake disc front, calibrating .
Replace the brake disc if it displays signs of heavy wear, variable thickness or similar. To replace, see Replacing front brake discs .
NOTE:
Minimum recommended disc thickness/replacement limit = 23.0 mm. Minimum recommended disc thickness when installing new brake pads = 23.8 mm. For 16" brake discs the minimum thickness/replacement limit = 25 mm. Minimum recommended disc thickness when installing new brake pads = 25.8 mm.