Proform 66753 3/8 x 1" Wedge Locking Header Bolt, Pack of 12

Each PROFORM® Grade 8 Header Bolt is permanently assembled with a pair of special washers. When the bolt is torqued to 28+ Foot-Pounds, the washers’ super hardened external teeth bite into and grip the bottom of the bolt head and the top surface of the header. After being self-locked in this manner, any bolt loosening rotation is blocked by a wedge locking action created by the washers’ interfacing, matching cams. It’s an uphill climb - vibration that might ordinarily loosen the bolt actually increases the wedge-locking tension, securing the bolt even more. Because this simple wedge locking method uses tension instead of friction, contact with oil actually facilitates the wedge effect. When changing headers, PROFORM Header Bolts can be untightened with a normal wrench, lubricated, and reused.