Ducati Diavel Workshop Manual page 85

Maintenance operations
Top-up with specified fluid (Sect. 3 - 2, Fuel, lubricants and other fluids) until reaching the MAX notch.
Hold the lever pulled towards the handgrip and simultaneously tighten the calliper screws (1) to a torque of 43 Nm
±10%(Sect. 3 - 3, Frame torque settings).
Checking rear brake pad wear
Remove the rear brake calliper (1) by loosening the screws (2).
Check brake pads wear through the inspection hole in the callipers.
Change both pads if friction material thickness of even just one pad is about 1 mm.
Warning
Friction material wear beyond this limit would lead to metal support contact with the brake disc thus compromising
braking efficiency, disc integrity and rider safety.
Change the brake pads as follows.
Remove the safety cotter pin (3) from the pad sealing pin (4).
Withdraw the brake pad retaining pin (4) and pull it out.