- SAE grade 5 bolts are easily identified by three hash marks on the top of the bolt head. Bolts rated at grade 5 are forged with medium carbon heat-tempered steel and have a tensile strength rated at 120,000 pounds per square inch. At this pressure, the bolt will begin to neck, causing its midsection to contract. Torque specifications also rely on the bolt itself and the application method.
- When a bolt is fastened dry, it is clean and without any lubrication. Dry torquing allows the maximum torque to be applied to a grade 5 bolt. The torque specification also depends on the size and number of threads on the bolt. According to the U.S. Bolt Torque Specifications Chart found on the Rask Cycle website, a grade 5 bolt with a 1/4-inch diameter and 20 threads per inch can be dry torqued to 8 foot-pounds, whereas a 5/8-inch-diameter bolt with 18 threads per inch can be dry torqued to 180 foot-pounds.
- When the bolt is oiled before torquing, different specs must be followed, as the torque is lowered considerably. For example, the 1/4-inch-diameter bolt with 20 threads per inch can be torqued to only 6 foot-pounds, while the 5/8-inch-diameter bolt with 18 threads per inch can be torqued to only 130 foot-pounds, according to the Rask Cycle chart.
- Torque specifications are also lowered if the grade 5 bolt is plated. According to Rask Cycle, bolts with a dry film, such as teflon or a dry wax, can be torqued to only 50 percent of the original torque specification. Those with cadmium plating should be reduced 25 percent, while zinc-plated bolts should be reduced 15 percent. There is no change in the torque specifications for grade 5 bolts plated with chrome.
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