CRITICAL: BUY QUALITY Performance aftermarket fastener manufacturers offer much higher tensile strength fasteners that are specifically designed for racing applications. ARP, for example, offers threaded fasteners that boast 170,000 psi, 190,000 psi and 220,000 psi. In other words, instead of hitting the local hardware store or Internet source for imported who-knows-what-or-where-they-came-from fasteners, stick with reputable [...]
METRIC NUT GRADES The grade system for nuts is a number that represents 1/10 of the specified proof load stress (in kgf/mm2). The proof load stress corresponds to the minimum tensile strength of the highest grade bolt that can be used with that nut. GRADE CAUTION Although it is common for Grade 5 bolts to [...]
THREADED FASTENER GRADES by Mike Mavrigian photos by author Grade 5 steel bolt. Three radial line marks. Theoretically, this bolt will feature a 120,000 psi minimum tensile strength. The grade label specifies the minimum strength properties the fastener is intended to meet. Industrial fasteners are also marked with a label that identifies the maker of [...]
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