Remove all rust and contamination from the disc surface, and then measure the disc thickness at 8 positions at least.
Rear brake disc thickness
Standard value : 10.0 mm (0.39 in)
Limit : 8.4 mm ( 0.33 in)
Thickness variation should not exceed 0.01 mm (0.0004in) (circumference) and 0.01 mm(0.0004 in) (radius) at any directions.
If wear exceeds the limit, replace the discs and pad assemblies for left and right of the vehicle.
Check the pad wear. Measure the pad thickness. replace it if it is less than the specified value.
Pad thickness
Standard value : 10.0 mm (0.39 in)
limit : 8.0 mm (3.14 in)
Check that grease is applied, to sliding contact points and the pad and backing metal for damage.