Originally Posted by Char_n_Kath
That, for certain, was the topic of much discussion and speculation between me and the mechanic, Rob.
Rob indicated that since there was no wear marks on the brake drum, it was his opinion that the sheer wasn't due to loose lug nuts. This made sense to me as I'm very careful about the lug nuts. Before the trip (planned as 4,000 miles), I properly torqued the lug nuts on all four wheels. This incident happened at about 1,500 miles into the trip. When the lug nuts on the other three wheels were checked, they were all still the same.
The other ideas were that the brake locked up and/or faulty lugs. If it were either of these, I can't think of any preventative measure that could be taken.
A couple things happened in just the right sequence to cause your failure. Five lug wheel hubs are designed to function with at least four lugs properly torgued to spec. for redundant safty reasons (does not apply to four lug design).
A few assumptions here to try and explain the failure. Initial wheel install was not proper. Your checking (by torque wrench) before the trip must be done with wheel up. Proper procedure is to loosen lugs, then re-torque the wheel to spec. Improper install prior to your re-torgue had already set the failure on its path. The wheel was not seated to the hub properly causing whats called http://www.knowswhy.com/why-do-lug-nuts-loosen/this
That condition continued until studs failed and wheel seperation occured. Heres the good news, no trailer damage.