Trouble: Brake pad wore down to metal-to-metal contact and subsequent rotor damage. No worn-pad audio warning sound generated as owner's manual specified. Observations:
- Warning sound tab is on outer pads only; pad wear was uneven; inner pad lining wore down to metal before signal tab on outer contacted rotor. Recommendation - All pads should have tabs.
- Brake caliper-to-steering knuckle attaching bolts are full- length threaded, coarse thread. Recommendation - Use solid shank fine thread bolts for better shear and tension strength.
- Rotor mounting holes are oversized and share wheel studs with wheels. Recommendation - Rotor should have dedicated fasteners, be located precisely and have zero play. Dito wheel. Noted aluminum transfer to rotor indicating relative rotational movement between the two components.
#3 above deserves additional attention. The assembly is layered such that I believe it can loosen and possibly disassemble itself. I wonder if this has happened in the field. Also the wheel studs are full-length threaded, which places them in shear loading on threads, in both rotational directions, in shock loading when the rotor shifts in their oversized mounting holes when in braking or power modes. I am also concerned about the excessive tension loads on these studs as the 100 lb-ft recommended torque is far beyond that listed in reference tables, even for 150,000 psi steel, FINE THREAD, which these bolts are not. Further complex stress occurs during suspension excursions and in steering. Car makers have been building their cars like this for decades, using cheap fasteners, quick but questionable assemblies and brute force to hold things together, but that doesn't make it right. They should think solid shank, fine thread, self-locking nuts, zero play tapered splines and in general, sound engineering emphasizing the concept of fail-safe, robust design.