WINTER 2025

90THE DISTRIBUTOR’S

90THE DISTRIBUTOR’S LINKGUY AVELLON WHAT FASTENER DISTRIBUTORS NEED TO KNOW ABOUT REPLACING WHEEL HARDWARE from page 10Most vehicles have a conical seated wheel nut andcan deform the concave wheel boss mating surfacefrom how the lug nut/bolts are installed. This is why tiremounting technique and retorquing the wheels allows forthe reseating of the conical or the ball seat of the mountinghardware into the concave wheel boss.Rust is formed from iron or the ferrous materials ofthe wheel hub and brake hat. Corrosion is a white productof metal reduction from non-ferrous materials, such as thealloy wheels. Both by-products will inhibit the proper seatingand tightening of any fastener joint.The corrosion products form a cushion layer which willcompress under loads, thereby relaxing the clamping forceof the connection as the loads settle in. Rust or debrisin the wheel boss area from repetitive damage of thewheel mounting hardware during reinstallations will alsoinhibit having a solid joint connection. Even if the corrosionparticles are cleaned by wire brushing, the term “rust neversleeps” is true. Wire brushing will help in most instancesto remove surface rust, but it will never completely removeimbedded chlorides.Salt and chloride compounds are significantlyaggressive to the point where their reaction becomesautocatalytic. This means that the reaction will continueto grow upon itself if the embedded chlorides are notcompletely removed, which is next to impossible withoutsand blasting or chemical treatment.Rust can cause joint separation from continual growthand expansion of the corrosion products, which willweaken the threads of the wheel nut from the pressure ofthis growth, causing damage to the threads of the wheelmounting hardware and loss of clamp load, or eventualthread stripping of the fastener’s threads. If the jointrelaxes 0.001” from contaminants and corrosion, thepreload loss produced is 30,000 psi.Thread deformation of the wheel nut is exacerbated byhow the wheel is installed. Most tire and repair shops useunregulated air impact wrenches to remove and remountthe wheels. What this means is these air wrenches operateoff an air supply regulator operating between 90-110 psiair pressure. This is not torque. Therefore, if one air tool isbeing operated at the same time as another is in use, theair pressure drops and the output of the wrench is reduced;no two lug nuts are ever tightened the same.The initial impact torque of a standard ½” or 12 mmpneumatic impact gun is 425 lb-ft. Passenger vehiclesrange between 80 to 115 lb-ft. The use of these hightorque, unregulated air impacting guns will destroy theinternal threads of a wheel nut with accumulated use, notto mention destroying the conical wheel boss surface ofthe wheel itself. Again, this is because the wheel lug nutsalmost never go back onto the same wheel stud and matewith the same wheel boss depression. Improper tighteningtechniques, such as not using a criss-cross pattern, willalso apply uneven loads to the wheel assembly.An impact wrench looks for friction to cause it to stall.If the operator senses a slight hesitation, he will impactthe nut harder and faster to ‘overcome’ any obstacleslike thread nicks or burrs. It is this type of impacting thatweakens the threads of the nut and initiates stresses inthe thread roots of the wheel studs. Damaged wheel lugnuts will have rounded hex corners or other visible signs ofexcessive torque. This is a sign that the lug nuts should bereplaced immediately.Full torque should never be placed on one wheel nut.Many times, the lug nut or stud bolt are threaded on for thefirst few threads, then run full-on into the wheel with theimpact gun. The lug nuts and stud bolts should always betightened by hand or at a low torque to position and set thewheel, then in a criss-cross manner, tighten the wheel nutsto the final torque.All auto and truck manufacturers specify using atorque stick or torque wrench to avoid warping damageto the brake rotors. They also specify that the wheel nutsshould be retightened within 100 miles of driving to be sureresidual joint relaxation is reset.CONTINUED ON PAGE 126

THE DISTRIBUTOR’S LINK 91