GMNA GM255M PDF

This standard covers the mechanical and quality requirements for nine grades of steel bolts, screws, studs, sems, and U-bolts with hardness of HRC 39 maximum. Tapping screws, thread rolling screws and self drilling tapping screws are not included.

The term ‘stud' as referred to herein applies to a cylindrical rod of moderate length, threaded on either one or both ends or throughout its entire length. It does not apply to headed, collared or similar products which are closely characterized by requirements shown herein for bolts.

For Specification purposes this standard treats ‘U-bolts' as studs. Thus, whenever the word ‘studs' appears ‘U-bolts' are also implied. U-bolts covered by this standard are those used primarily in the suspension and related area of vehicles. (Designers should recognized the ‘U' configuration may not sustain a load equivalent to two bolts or studs of the same size and grade; thus actual load carrying capacity of U-bolts should be determined by saddle load tests.