Lately I have had the steering wheel shake upon braking. I went after the usual suspects, but found a new one: deep corrosion in one of the new Volvo rotors, shaped like the pad. All I can think is that I washed the car, soap and water got trapped between the rotor and pad, and I did not drive the car for days. Maybe next time I wash the car I should drive it and use the brakes enough to dry rotors and pads.