"Warped brakes" are usually uneven pad deposits on the disc surface. Steel discs don't really warp, they'll crack if anything. Pad deposits can be visible, but sometimes not... They can be clear and you can't see it. I've had a lot of brake issues with my cars driving really hard with huge temperature swings with all sorts of pads. The Z has had a nasty vibration under braking so my fix... Use Carbotech race pads to clean the surface, they chew light pad deposits up just fine, and then bed my street pads back in. Beats paying to have your discs resurfaced or buying new ones. Look at that beautiful disc! Good as new.
Have you guys had pad deposit issues with you Z? My buddy with a 350Z mentioned his car was always prone to it as well.
