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For the trucks that keep America moving

1-877-587-9888

Leaf spring guides

Truck sagging on one side?

A truck that leans, squats under load, or hits the bump stops is telling you the springs are done. Here is how to confirm it, and what actually fixes it.

Find springs for your truck

Diagnosis

Check it in five minutes

Park on level ground and measure. No tools beyond a tape.

Rear view of a pickup truck sitting visibly lower on one rear corner, with a vertical measurement line at each rear wheel from hub center to fender lip.
Measure hub center to fender lip on both sides of the same axle. The sagging side comes up short.
  • Measure both sides. Hub center to fender lip, left and right, same axle. A difference of an inch or more points at the springs.
  • Look at the arch. A healthy spring holds a visible curve. Flat leaves, or leaves curving the wrong way, mean the steel is fatigued.
  • Inspect each leaf. Cracks, a snapped leaf end, or leaves that have shifted sideways are replace-now findings, not watch-it findings.
  • Check the bushings and hardware. Dried, cracked, or missing bushings in the spring eyes let the whole pack sit wrong. U-bolts are one-time-use hardware, so plan on new ones with any spring job.
Engineering side view of a leaf spring on an axle with U-bolts, with four numbered markers on the inspection points: 1 the eye bushings, 2 a crack in a leaf, 3 leaves shifted at the clip, and 4 the U-bolt plate.
Work the four numbered points in order. If any of them fails, replace the pair on that axle.

Why it happens

Springs are a wear item

Steel fatigues. That is the whole story, and it happens to every truck that works for a living.

Engineering comparison of the same leaf spring healthy and worn: the healthy spring shows a tall arch measurement between the eye line and the crown, the worn spring below has flattened and its arch measurement is a fraction of the size.
The same spring, measured the same way. Fatigue flattens the arch, and ride height drops with it.

Every load cycle flexes the steel, and over years the spring loses arch and capacity. The truck sits lower, leans toward the harder-working side, and rides the bump stops with weight in the bed. Age plus load does this to original springs on any high-mileage truck. It is not a defect. It is the part reaching the end of its service life.

Two fixes get suggested in every forum thread: add a leaf, or air bags. Both have their place, and neither restores a worn pack. An add-a-leaf props up fatigued steel. Air bags carry load but mask the sag rather than fix it. When the pack is done, the fix is a new pack.

The fix

Replace the pair, match the load

Two decisions: both sides at once, and the right capacity for how the truck actually works.

Replace both sides of the axle together. Springs are sold individually, so that means ordering two. Pairing new steel with tired steel keeps the truck uneven and works the new spring harder than it should.

Then match capacity to your real load. Hauling the same weight every day is a different spec than an empty daily driver that tows a few weekends a year. Our capacity guide walks through leaf counts and ratings. If you are not sure, tell us the truck and what it carries, and we will spec it.

Springs from the factory that makes them

APM has built leaf springs since 1971 and runs its own plants. The springs in our catalog are the same OEM-quality packs we manufacture, listed with leaf counts, measurements, and cross-references so you can match what is on your truck.

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