Sagging or broken coil springs cause uneven ride height, poor bump absorption, and bottoming on trail — replace them in pairs (both fronts or both rears) with either Mopar OE or aftermarket lift springs sized to your build.
Stock JK coil springs are progressive-rate units that settle over time, especially under bumpers, winches, and roof racks. After 100,000 miles, a stock spring can sag 0.5"–1" below its original free length. Mismatched ride height (one side lower than the other) usually points to one tired spring or a cracked coil — and it shows up at the wheel arch height before you feel it in the seat.
You have three replacement paths. First: Mopar OE springs (52126318AC heavy-duty front for Rubicon-spec ride height, 52126314AC for Sport/Sahara front, 77070091 rear) — these put you back to factory geometry. Cost is around $75–$95 per spring. Second: aftermarket lift springs paired with longer shocks for 2"–3" of lift. Old Man Emu, Rough Country, Rubicon Express, and Teraflex all offer matched coil sets. Third: heavy-rate replacement coils to compensate for added weight (bumper, winch, half doors removed for permanent door storage) without adding lift.
Springs always replace in pairs. Mixing a new spring with a tired one will give you a measurable lean. Replace fronts together, rears together — or all four at once if you're upgrading the build.
Front install: support the frame on jack stands, disconnect the track bar at the axle, the sway bar end links, and one front shock per side. Drop the axle slowly with a floor jack — the front spring will lift out by hand once tension releases. Rear install: same approach but the rear sway bar disconnect is built into the geometry, and you'll need to disconnect the rear track bar. Watch the brake hoses and ABS lines as the axle drops.
Reassemble with the spring isolators (rubber pads at top and bottom) in place — missing isolators cause coil clunk over bumps. Torque shock bolts to 56 ft-lb, track bar bracket bolts to 125 ft-lb, sway bar end link to 75 ft-lb. Get an alignment after — caster changes as ride height changes.
| Part | Vendor | Est. price |
|---|---|---|
| Mopar Heavy Duty Front Coil Spring (Rubicon/HD) | Mopar | ~$95 |
| Mopar Front Coil Spring Right (Sport/Sahara) | Mopar | ~$75 |
| Mopar Rear Coil Spring | Mopar | ~$80 |
| Old Man Emu 2.5" Heavy Duty Coil Set (JK) | ARB / OME | ~$480 |
| Rough Country 2.5" Coil Spring Set | Rough Country | ~$210 |
Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.