A broken coil spring rarely announces itself. You hear a clunk over speed bumps, notice the car sits crooked in the driveway, and end up reading about how to replace coil springs on a Saturday morning. On paper the job is simple.
The catch is that a compressed spring stores enough energy to take a hand off, and that fact shapes every step.
Manufacturer service data typically puts strut-to-knuckle bolts somewhere in the 100 to 200 Nm range, and a lot of those fasteners are single-use torque-to-yield bolts you cannot reuse. So before we talk about which tool to grab, let's get the actual procedure straight.
How to Replace Coil Springs
Replacing coil springs means removing the strut assembly and compressing the spring. You need a proper spring compressor and new springs in pairs. Never stand in line with the spring axis.
Swap the upper mount and bump stop while it's apart. Then torque every fastener to spec and book an alignment.
Why a Coil Spring Is Never Just Another Bolt-On
The stored energy problem
At ride height, a coil spring is already holding up a quarter of the car. Compress it another few inches and you've loaded a steel coil with real energy. If a hook slips, that energy leaves in a fraction of a second.
Stored-energy guidance from safety bodies like OSHA treats compressed springs as hazardous loads, not spare parts. That reframing changes how you work.
Why "replace the spring" is often the wrong job
Most cars past ten years old don't leave the shop with just a spring. The upper mount bearing is usually dry, the bump stop is crumbling, and the damper has done its miles. You've already paid to get in there.
Reusing those bits means paying twice.
What a broken spring feels like
Usually nothing dramatic. A sharp clunk over broken asphalt. A car that leans slightly to one side.
Sometimes a rattle that sounds like a loose heat shield. By the time you can see the break, the end coil has often snapped clean and dropped onto the perch.
And a spring that failed at 90,000 miles didn't fail alone. Something caused it, usually corrosion at the perch or a damper that stopped controlling motion years ago. Fix only the spring and the new one inherits the same problem.
What You're Actually Dealing With: Struts, Seats, and the Parts That Fail
Two layouts dominate. A MacPherson strut wraps the spring around the damper and bolts to the knuckle as one unit, which covers most front ends on passenger cars. A separate spring-and-shock layout puts the spring in its own perch, common at the rear.
The numbers that decide fit
Spring rate, wire diameter, free length, and the shape of the spring ends all matter. Closed-and-ground ends sit flat against the seat. Open pigtail ends have to index into a step machined into the lower perch.
Get that clocking wrong and the spring sits cocked. You'll hear a clunk, then find a crack.
The parts that quietly die alongside it
- Upper strut mount and bearing
- Bump stop and dust boot
- Coil isolator and spring seat
- Torque-to-yield mounting bolts
Reading the failure
Sag shows up as lost ride height, not as a visible crack. Corrosion pits the bottom coil right where it sits in the perch. Spring ident codes and colour bands tell you which rate the factory fitted.
They're the only reliable way to match a replacement, so photograph them before you order.
If the ball joints and factory-style chassis parts are original too, plan for them now. One tear-down beats two.
Quick Strut or Bare Spring? Choosing Your Route Before You Touch a Tool
The first real decision is whether you compress anything at all. A bare spring swap keeps your existing damper and mount. A complete loaded assembly, often sold as a quick strut, arrives with spring, damper, mount, and boot already bolted together.
| Route | Best for | Watch out for |
|---|---|---|
| Bare spring swap | Healthy dampers, tight budget | Needs a compressor and a new mount |
| Quick strut | Rusty or high-mileage cars | Ride can feel firmer than stock |
| Coilover kit | Height or damping changes | Higher cost, needs proper setup |
Which compressor is safe to rent
Two-hook compressors are the common rental. Clamshell designs grip the whole coil and are harder to get wrong. Wall-mounted units belong in shops.
Skip anything without locking pins or a safety cage, no matter how cheap the deposit.
OEM, aftermarket, or salvage
OEM-spec springs match the original rate and ride height. Reputable aftermarket equivalents are fine when the part number crosses over cleanly. Used springs from a breaker are a gamble, since you can't see the fatigue history.
Matching the job to your car and climate
If the car has lived through salted winters, budget for loaded assemblies rather than bare springs. Compressor rental still runs about $20 to $40 a day at parts chains as of 2026, so the maths often favours buying the complete unit on an older vehicle.
The Step-by-Step: Replacing Coil Springs Without Betting Your Hands
Before the car goes up
Measure ride height at all four corners first. Use hub-to-fender arch, on level ground, with tyre pressures set. That baseline is how you prove the job worked.
Buy springs in pairs and pull the torque table from the service manual before anything moves. If you're lifting the front end at home, use rated stands on hard ground.
Getting the assembly out
Crack the wheel nuts and hub nut while the car still has weight on its tyres. Hand tools first, always. An impact gun has its place on lugs, as our notes on spinning off wheel nuts explain, but it never touches a spring compressor.
Disconnect the ABS sensor wiring and the brake hose bracket. Support the knuckle with a strap or a jack so it doesn't hang on the hose or pull a CV joint apart. Then remove the strut-to-knuckle bolts.
If the tie rod ends are original, decide now whether pricier linkage parts earn their keep.
Compressing and swapping the spring
Mount the compressor squarely. Alternate sides half a turn at a time. Keep the hooks fully seated and the safety pins in.
Compress only enough to unload the top nut. Lift the mount off and note the washer order. Seat the new spring with the pigtail indexed into the lower step.
Get that wrong and you'll hear it for months.
Going back in
New mount, new bearing, new bump stop, new boot. Reassemble and torque the top nut to spec. Fit new torque-to-yield bolts wherever the manual calls for them.
Bounce and roll the car before final torque on rubber-bushed joints, then book the alignment the same week.
Where This Job Turns Dangerous: Corrosion, Compressors, and Stop Signs
Compressor mistakes that hurt people
Three repeat offenders. Using an impact gun on a screw-type compressor. Gripping too few coils, so the spring can't clear the top nut.
And half-seated jaws that walk off the coil under load. Any of those turns a spring into a projectile. Wear eye protection and never stand in line with the spring axis.
When the assembly is scrap, not the spring
If the perch is perforated, deeply pitted, or the strut housing is rotting through, stop. That's no longer a spring job. A fresh spring on a corroded perch will crack the same way within a season.
On salted-road cars, loaded assemblies are often the cheaper answer.
The shortcuts that come back
Cutting coils to drop ride height ruins the rate, wrecks the seating, and fails inspection in most jurisdictions. Fitting one spring instead of a pair leaves the car leaning and the handling unpredictable. Reusing stretched fasteners is another one.
If the wheel hardware is tired, price a fresh set before you start.
Collateral damage to check before you drive
CV joints pulled apart. Stretched brake hoses. Broken ABS wires.
A seized damper shaft that spun out of the mount. All of these happen on the way out, not on the way back in. Check for an open recall by VIN through NHTSA as well, since several manufacturers have run spring corrosion campaigns.
Costs, Torque Specs, and What the Job Really Takes
A pair of OEM-spec springs usually lands between $120 and $400. Loaded quick struts run $150 to $350 each, which is why older cars often get the complete unit instead. Compressor rental adds $20 to $40 a day.
| Item | Typical cost | Notes |
|---|---|---|
| Spring pair (OEM-spec) | $120 to $400 | Buy in pairs, always |
| Quick strut, each | $150 to $350 | Includes mount and damper |
| Compressor rental | $20 to $40 a day | Often a refundable deposit |
| Four-wheel alignment | $100 to $200 | Book it the same week |
| Shop labour, per axle | $300 to $700 | Alignment usually extra |
How long does it take?
Plan one to two hours per corner with hand tools. A rusty car with seized bolts can eat a whole weekend. Add an afternoon for the alignment appointment.
The measurements that prove it worked
Ride height is the scorecard. Measure hub-to-fender arch before and after, on level ground, with tyre pressures set. Side-to-side difference should sit within about 10 mm.
Check spring free length and wire diameter against the old part before anything goes back together.
Torque reality
Strut-to-knuckle bolts often fall between 100 and 200 Nm. Top mount nuts usually sit around 40 to 70 Nm. Angle-torque fasteners are measured in degrees, not Nm, and they get replaced rather than reused.
Pull every number from the service manual for your exact model.
When to Hand the Car to a Shop, and What to Verify Afterwards
Some cars stop being driveway jobs. If the perch is perforated, the strut housing is rotting through, or the top nut has seized onto a spinning damper shaft, a shop with a wall-mounted compressor earns its money. Same answer if the car has no safe jacking points left.
Use a simple if/then rule. If the spring is broken but the housing is sound, a bare spring swap works. If the housing is corroded, replace the whole assembly.
If you can't get a counter-hold on the damper shaft, stop and book it in.
What to check before you drive away
- Four-wheel alignment completed the same week
- Top mount nuts re-torqued after about 50 miles
- Ride height re-measured at all four corners
- Brake hose and ABS wiring routed clear of the spring
- Road test over broken surfaces at low speed
What to say to the shop
Tell them which corner failed and what you've already replaced. Ask for the alignment printout and the torque values they used. If one spring is broken and they quote all four corners, ask them to justify it.
Disposing of the old springs
Old springs are scrap steel, worth a few dollars a pound. Release any remaining tension before they go in the bin. Never leave a compressed spring sitting in a garage corner.
Frequently Asked Questions
Do I have to replace both sides at once?
Yes, replace springs in pairs on the same axle. A new spring next to a sagging one leaves the car leaning and the handling uneven. Matched pairs keep ride height and spring rate consistent from side to side.
Can I drive with a broken spring?
Only to the nearest safe spot, and slowly. A fractured spring can drop onto the tyre or puncture it. If the broken end is touching rubber, don't drive it at all.
Call for recovery instead.
Do I really need an alignment after?
Yes, every time. Unbolting a strut changes camber and toe. Skip the alignment and you'll see uneven tyre wear within a few thousand miles.
It's the cheapest part of the whole job.
Can I rent a spring compressor, or should I buy one?
Rent if you're doing one job. A two-hook rental runs about $20 to $40 a day. Buy a clamshell or wall-mounted unit only if you'll use it repeatedly.
Avoid any compressor without locking pins or a safety cage.
Why is my car sitting higher on one side after the swap?
Usually a spring that isn't clocked into the lower perch, or a mismatched pair. Sometimes the suspension just hasn't settled yet. Recheck ride height after a few miles, then inspect the seating.
