Why you should not reuse U-Bolts

Suspension U-Bolts are manufactured with a smooth rolled thread, while the mating Hi-Nuts are manufactured with sharp cut threads.

When a U-Bolt is tightened 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-Nuts from the U-Bolt will cause a cross - threading that will not allow the U-bolt to be adequately retorqued.

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.

L&H recommends using a torque wrench when installing U-Bolts.