WINTER 2025

10THE DISTRIBUTOR’S

10THE DISTRIBUTOR’S LINKGuy AvellonGuy Avellon has been in MRO and Fastener Distribution for over 30 years, in such positions SalesEngineer, Chief Engineer, Manager of Product Marketing, Product Engineering & Quality andDirector of Quality & Engineering. He founded GT Technical Consultants where he performs failureanalysis, lectures on fastener safety, works for law firms and designs/audits Quality systems. He is amember of SAE, is Vice Chairman of the ASTM F16 Fastener Committee, Chairman of the F16.01 TestMethods Committee and received the ASTM Award of Merit in 2005. Guy can be contacted at 847-477-5057, Email: ExpertBoltGuy@gmail.com or visit www.BoltFailure.com.WHAT FASTENER DISTRIBUTORS NEED TO KNOWABOUT REPLACING WHEEL HARDWAREWith the start of the winter season, many will wantto add snow tires or just rotate them to be sure there isproper tread on the drive wheels. However, tires aren’tthe only items that may require replacement. Wheel studsand wheel lug nuts may also need to be replaced on aregular basis.When analyzing a wheel failure, most all failuresare due to metal fatigue of the wheel stud or stud bolt.Fatigue can be exacerbated from normal tractive loadsand bending to prying loads from cornering. All fatiguefailures are a result of losing clamp load. However, theroot cause may come from several sources.When the clamp loads are lost or reduced and theservice loads exceed the remaining clamp load, thethreads of the fasteners must absorb the excess load. Intime, a stress raiser develops in the thread root causing amicrocrack which grows and propagates through the grainboundaries of the wheel stud material until a completefracture occurs.The fractures will have the appearance of many fineparallel lines across a relatively flat and smooth surface,which are the result of the load cycling and repetitivenessof the external loads. Even the staccato braking of a4WD/ABS system can exacerbate a fatigue crack.Stress cracks will begin at the weakest area on thewheel stud; the thread run out of the wheel stud, whichis the last incomplete thread towards the head, or at thefirst thread outside the nut where the wheel contactsCONTRIBUTOR ARTICLEthe joint surface. The action of metal fatigue may becompared to the continual flexing of a coat hanger wireseveral times until it breaks.Wheel lug nuts are also susceptible to failure. Whenthe internal threads of the lug nuts become weakenedfrom continuous use and from assemblies using hightorque impact guns, the threads lose their strength andcause the joint connection to lose clamping force. Theinternal threads may strip at some time under corneringloads but the weakened threads will surely cause stressraisers in the threads of the wheel studs to form metalfatigue.There are five major reasons for how the wheel clampload is lost; road hazards, rust/corrosion, not retorquingthe wheel lug nuts or stud bolt after remounting the wheelafter driving a minimum of 25 miles, reusing the same lugnuts after 100,000 miles and incorrect wheel installation.Road hazards are generally on the right side of the vehiclein the form of frost heaves, road grates, pot holes,etc. but will affect the left side when the wheels arerotated. Impact and shock loads to the wheel will causeembedment of the wheel lug nut into the wheel bosssurface and affect wheel alignment.During tire rotations, the wheel is now rotated toanother location. It is common practice for the mechanicto leave the lug nuts or wheel bolts with the wheel huband move the tire to where different wheel lug nuts/boltsare used that have a different mating seat impressionCONTINUED ON PAGE 90