SAE J2316_202111

This SAE Recommended Practice provides a uniform procedure and performance requirements for evaluating fastening systems for normal highway use on aftermarket passenger cars and light trucks (except dual wheels, which are covered by SAE J1965) and multipurpose passenger vehicles. The fastening system includes the wheel, wheel bolts, and wheel nuts, as well as vehicle mating surface. The coefficients of friction for steel and aluminum mating surfaces are provided based on information available. Many factors must be considered in design and validation of wheel attachments for each specific vehicle. Where the procedure is used for original equipment applications the vehicle manufacturers specifications supersede those noted. Original Equipment Manufacturers (OEMs) have control of their wheels, bolts, nuts, and mounting surfaces, and the finishes thereof that are known to affect the wheel fastening system. Their fastening systems can be optimized in the presence of controlling all the components that affect the fastening system. The OEMs all have their own acceptance criteria, so those listed in this document are not applicable. Aftermarket wheel, bolt, and nut manufacturers design their components to be used in multiple applications and they do not control of all the components. The minimum tension values, at the service torques recommended by the OEMs have been found to be serviceable for aftermarket aluminum wheel fastening system applications. See Table 1. The name of the document is changed from “Wheel Nut Seat System” to “Wheel Fastening System” to broaden the scope of the components to include wheel nut seats, bolts, nuts, and finishes. Multiple editorial changes are recommended to clarify the intent of the procedure. The fastener size M14x2.0 is added because it is now relevant and has been tested. In practice, vehicle manufacturers publish recommended torque for specific vehicles so vehicle owners can retighten their lug nuts. These torques grouped reasonably well by approximate bolt size, hence binning them in Table 1. At the high end of the torque tolerance there is a concern of stripping the nut and or stretching or fracturing the bolt. It is recommended that no stripping, of the nut and or stretching or fracturing the bolt to be observed at 120% of the service torque. A formula has been added to determine minimum bolt tensions for specific configurations and applications. Said formula is based on a clutch theory known to be used in the industry rendering the ideal minimum tensions. The formula assumes the ideal friction necessary to disallow relative torsional motion between wheel and hub. The friction in service is not ideal. service friction is reduced by particulates of corrosion, unintended lubricants from tire and axle lube. The service friction factor is found empirically from the frequency distribution of data from measuring tension at torque on copious rundowns using QEM studs, nuts, and wheels of steel and aluminum.