Greater care is required when replacing loose or broken U-bolts. These things clamp the axle to the suspension and are therefore subject to huge stresses.
The fasteners need to be torqued properly. Never reuse a U-bolt or the nut. Once they have been properly torqued, they stretch and can’t be retorqued properly again.
Truck Repair Technology
The technology and Maintenance Council’s Recommended Practice 643 recommends using a wax based lubricant on the U-bolt threads to ensure proper clamping force, and using a torque wrench to precisely set the fastener clamping force.
Also, TMC recommends running the truck on a course where maximum articulation of the suspension occurs after installation, then loading the suspension before retorquing the U-bolts. They should be retorqued again between 3,000 and 5,000 miles after replacement.
Bob Borsam, tech support manager, vocation product, at Hendrickson, recommends a suspension torque check on every new vehicle before it goes into service.
Not to speak ill of the OE assemblers, but torque values set at the factory can clip as the suspension settles during delivery.
“It’s a really good idea to torque the suspension fasteners when the truck is new, and again after a couple of thousand miles of regular service,” Borsam says. “We’ve found that makes a big difference a year and a half down the road, especially in severe service applications.”
At Myers Diesel Repair we have all sizes of threaded rod and our VicRoc U-bolt bender to make any U-bolt you may need from 1/4 inch to 1 1/4 inches.