By Tom Joyce tjoyce@mtairynews.com A sport that involves circling racetracks at 200 mph while measuring success in nanoseconds requires lots of moving parts other than car and driver, and a Surry County resident has had a hand in many of those. “Ever since I was little, that’s all I could think about was race cars,” David Cropps said in discussing his 20-year career in NASCAR, which now involves working at Richard Petty Motorsports — headed by “The King” of stock car racing. “My main job is front-end mechanic,” Cropps, 42, of Mount Airy, said regarding his present position with the Petty organization, where he has been employed for a total of 13 years. It’s one of various racing teams he has served with over the past two decades, encompassing all three top rungs of NASCAR — the Cup, Xfinity (formerly Busch) and truck series.