Originally Posted by Iron Rey
Also, I do not know of ANY manufacturer that reccommends you "scruff" the disk when you change the pads,
Scruffing the disc can be a remedy for brake shudder. I would prefer to call it roughing the disc. Use sandpaper, 220 grit. You're not trying to remove material but change the surface and remove any brake pad compound that is causing the shudder.
Also, my reference was to the scuffing the pads. This breaks the glaze and brings up a new surface on otherwise good pads with mileage remaining. Sandpaper can be used here as well.