Steering & Suspension Inspection

Suspension SAG Measurement – How Much Is Too Much on Old Springs

Posted by author-avatar

Old springs sag over time, which lowers the car, changes alignment angles and wears out struts. A 10-year-old sedan or SUV that sits lower than it did new may have sagging springs. This guide shows how to measure suspension sag at home and know when the springs need replacement.

What the driver feels

  1. The car sits lower than it used to, especially in the rear
  2. The headlights point too low after a few years
  3. The rear sits lower when loaded with passengers
  4. Uneven tire wear from changed camber angles
  5. The car bottoms out over railroad tracks or big bumps
  6. The struts or shocks look fully extended (no travel)
  7. The car leans more than it used to in corners
  8. Fenders sit closer to the tires than when new

On a 2014 Honda Accord or Toyota Camry, the coil springs sag about half an inch over 10 years. The sag is normal, but if the car sits more than an inch lower than new, the springs are fatigued. Sagging rear springs on older sedans cause the rear to tuck under when loaded, which wears the rear tires on the inside edges.

On SUVs and trucks like a 2015 Ford Explorer or Toyota Highlander, the rear springs sag from carrying kids, cargo and occasional towing. The sag changes the alignment geometry, which causes rapid tire wear. On older trucks, the front coil springs can also sag, especially on V8 models with heavier engines.

How to inspect it

Safety note: Always set the parking brake and chock the wheels before getting under the vehicle. Use rated jack stands, never rely on a jack alone.

  • Park the car on a flat surface with a full tank of gas and nobody inside.
  • Measure from the ground to the center of the front fender lip on both sides.
  • Do the same for the rear fender lips.
  • Compare left to right – more than half an inch difference means a weak spring on the low side.
  • Look up the factory ride height specification for your car (online or in the service manual).
  • If the car sits more than one inch lower than the factory spec, the springs are sagging.
  • Bounce each corner of the car. If it bounces more than once after you push down, the shocks are also worn.

Repair and replacement advice

  • Replace sagging springs in pairs, even if only one side looks low.
  • While the springs are out, replace the struts and strut mounts too – you are already there.
  • Sagging rear springs on a truck or SUV can be corrected with helper air bags or overload springs.
  • After spring replacement, get a four-wheel alignment because the geometry has changed.
  • Do not just crank the torsion bars on a 4×4 to fix sag; it wears out the bushings and shocks faster.

Need Steering & Suspension Parts?

Send us your VIN or OE number to get a fast wholesale quote. We stock quality steering racks, pumps, tie rods, control arms and suspension components for domestic and import vehicles.