GMW 25

his specification defines the mechanical and material requirements for externally threaded fasteners sized M39 and smaller. This specification is based on ISO 898-1. However, only property class described in this document shall be used.
Material Description. The fasteners applicable to this specification are formed from wire steel and heat treated by quench and tempering, as required by the property class. The chemical composition, internal cleanliness of the steel, mechanical properties, microstructure, and other physical properties are described in this document.
Symbols. Not applicable.
Applicability. This specification applies to bolts, screws, SEMS (bolts with washer assembly), threaded plugs, and studs.
Remarks.
GM does not allow new release of fasteners with property class 9.8. The properties listed are for reference for legacy parts only.
General Motors have restrictions on usage of fasteners above property class 10.9. Fasteners above property class 10.9 shall be released only after approval from GM Fastener and Materials Engineers. Special “underlined grades” (identified as 12.9 and 10.9 for example) per ISO 898-1 are not permitted.