Threaded Fasteners 00.04 General Information Threaded Fastener Types The majority of threaded fasteners used throughout the vehicle have U.S. customary threads (diameter and pitch are measured in inches). See Fig. 1 . How- ever, the engine and some items attached to the cab use metric fasteners (diameter and pitch are mea- sured in millimeters). 2 3 4 Most threaded fasteners used on the vehicle that are 1/2-inch diameter or larger are plain hex-type fasten- ers (non-flanged); all metric fasteners are non- flanged.
Special hardened flatwashers are used under the bolt head, and between the part being at- tached and the hexnut, to distribute the load, and to prevent localized overstressing of the parts. The washers are cadmium- or zinc-plated, and have a hardness rating of 38 to 45 HRC. 1 5 6 7 1/2−13 x 1−1/2 A Some fasteners smaller than 1/2-inch diameter are flanged fasteners, which have integral flanges that fit against the parts being fastened. The flanges elimi- nate the need for washers. 9 10 NOTE: The standard fasteners used to as- semble the vehicle frame and to attach compo- nents to the vehicle frame are threaded lock- bolts (Spin Hucks). These fasteners are covered in Section 31.00 .
8 11 12 13 14 Fastener Grades and Classes Fasteners with U.S. customary threads are divided into grades established by the Society of Automotive Engineers (S.A.E.) or the International Fastener Insti- tute (I.F.I.). The fastener grades indicate the relative strength of the fastener; the higher the number (or letter), the stronger the fastener. Bolt (capscrew) grades can be identified by the number and pattern of radial lines forged on the bolt head. See Fig. 2 . Hexnut (and locknut) grades can be identified by the number and pattern of lines and dots on various sur- faces of the nut. See Fig. 3 . Nearly all of the bolts used on the vehicle are grades 5, 8, and 8.2.
Match- ing grades of hexnuts are always used: grade 5 or grade B hexnuts are used with grade 5 bolts; grade 8, grade C, or grade G (flanged) hexnuts are used with grade 8 or 8.2 bolts. M12−1.5 x 30 f310223a 10/19/93 B A. Bolt with U.S. Customary Threads B. Bolt with Metric Threads 1. S.A.E. Grade Marking 2. Thread Pitch 3. Nominal Diameter 4. Bolt Length 5. Nominal Diameter in Inches 6. Thread Pitch in Threads per Inch 7. Bolt Length in Inches 8. Metric Class Marking 9. Thread Pitch 10. Nominal Diameter 11. Bolt Length 12. Nominal Diameter in Millimeters 13. Thread Pitch (thread width from crest to crest in millimeters) 14.
Bolt Length in Millimeters Fasteners with metric threads are divided into classes adopted by the American National Standards Institute (ANSI). The higher the class number, the stronger the fastener. Bolt classes can be identified Fig. 1, Fastener Size and Thread Identification by the numbers forged on the head of the bolt. See Fig. 4 . Hexnut (and locknut) classes can be identified by the marks or numbers on various surfaces of the Business Class M2 Workshop Manual, Supplement 0, January 2002 050/1