PLEASE NOTE: Removed U-Bolts should NEVER be reused; they should be discarded.
Suspension U-Bolts are manufactured with a smooth cold-rolled thread, while the mating Hi-Nuts are manufactured with sharp cut threads. When a U-Bolt is tightend to its recommended torque level, the U-Bolt threads stretch as they mate with the Hi-Nuts. Although, not always visible to the naked eye, this damages the threads. Removing the Hi-Buts from the U-Bolt will cause a cross-threading that will not allow the U-Bolt to be adequately re-torqued.
A common practice in most maintenance facilities is to use an impact wrench to tighten U-Bolts. Consistent, accurate torque is next to impossible to obtain with an impact wrench, and in most cases an over-torqued fastener is the result. We recommend using a torque wrench when installing U-Bolts. New U-Bolts should be torqued after 2 weeks of usage.