Suspension Upgrades

Keeping the running gear under load

Staying ahead of the running gear is cheaper than a roadside repack in August. The jobs here are the ones that wear out mile by mile, and most come down to matching a part to your axle's rating and torquing it correctly.

The common jobs break down like this:

• Wheel bearings. Repack kits from Lippert are sold by axle capacity — a 5,200 lb kit and a 6,000 lb kit use different components, so match the rating stamped on your axle tag. Fresh grease and new races once a year or every 12,000 miles is the standard interval.
• Lug nuts. Match thread size and seat. The McGard sets here come in 7/16"-20 and 1/2"-20 with a conical (cone) seat — the wrong seat won't clamp the wheel evenly no matter how tight you run it.
• U-bolts. The clamps holding the axle to the springs stretch over time. Replace with a correctly sized kit like the Dexter K71-293-00 and torque to spec — a loose U-bolt lets the axle walk.
• Air springs. On the tow vehicle, a Firestone air-spring kit with an on-board compressor levels a squatting rear end under hitch weight. It supports the truck, not the trailer, but it's the fix for a nose-down tow.

Do the bearing and U-bolt work while you're already under there for a spring or equalizer job. And if the truck squats or the trailer wanders, an air-spring kit paired with a weight distribution and sway setup is what levels the whole combination out.