Just rechecked the new brushes after 80 miles. They are slowly wearing in to match the rotor. My on-board voltmeter has not shown any unusual voltage fluctuations so all seems fine with the DIY brush setup.
I don't think it's important for the whole face to contact the rotor. If you were to read ohms from a point on the face vs reading from something in contact with the whole face I don't think there would be a difference. You could test that by measuring with the point of the probe and then lay the probe on it sideways and read again. But the larger the area the slower it would wear for a given spring pressure.Just rechecked the new brushes after 80 miles. They are slowly wearing in to match the rotor.
I thought maybe you'd nail it on, lol.
I don't think it's important for the whole face to contact the rotor...