2209 Stewards Proposal #22: Lug bolt length

Standard height nuts are designed so that when fully engaged on a stud or bolt (1 thread showing to ensure full engagement) and the assembly placed in tension (threads in shear), the bolt or stud will fail in tension before the threads strip out. A wheel nut that is longer than a standard nut, as long as it is engaged on a stud for a length equal to the height of a standard nut and built to the same standards of strength and fit as a standard nut, will not hold any additional load. The length of thread engagement to ensure full strength is approximately 75% of the nominal stud/bolt diameter. Standard nut height is approximately 85% of the nominal stud/bolt diameter. The applicable standards for fasteners made of carbon or alloy steel are in BS EN ISO 989-1.
 
I'd support a rule like what Toby and Steve are describing. If tech sees that there appears to be less than 80% thread engagement (due to thick spacers with stock studs or whatever) you could check it quickly with a cheap digital caliper.

Is it too late to change the proposal?
 
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