- Is it safe to use? No. A door with a broken extension spring is unbalanced and can slam down hard on one side.
- Can I keep using the door? No. Do not cycle the opener, and do not lift the door by hand – one side now weighs far more than the other.
- Should I stop immediately? Yes – and if the broken spring has no safety cable running through it, keep everyone away from that side of the door entirely.
- Most likely cause: Metal fatigue at the spring’s end loops – the standard way extension springs die, accelerated near the coast by corrosion.
- How urgent is the repair? Same-day. The door is unbalanced now, and the second spring is the same age as the one that failed.
- Check for safety cables: look through the center of each extension spring for a steel cable running its full length. If the broken spring has no cable, treat the area as hazardous and keep clear – broken halves can still shift.
- Leave the door in its current position – closed if possible – and stop using the opener.
- Book a same-day repair and mention “extension springs, both sides” – it tells the technician exactly what to bring.
Extension springs are the long, slender springs mounted above the horizontal track on each side of the door – they stretch as the door closes and contract to help lift it, unlike torsion springs, which twist on a shaft above the door opening. When an extension spring breaks, the two halves recoil violently; the safety cable running through the spring is the only thing that contains them. A door with one broken extension spring is out of balance – one side heavy, one side light – which is why it slams, sits crooked, or refuses to lift evenly. Replacement is professional work, always in matched pairs, and always with safety cables installed.
Symptoms — You’ll Notice
- A loud crack or snap from the garage, often while the door was moving.
- The door sits or moves crooked – one corner lower than the other.
- A spring visibly hanging, drooping, or in two pieces above the horizontal track.
- The door slams the last foot or two when closing, harder on one side.
- The opener strains or reverses trying to lift the heavy side.
If the broken spring has no safety cable through it, do not touch the spring, the track, or the door on that side. Uncontained spring halves store real energy and can shift when the door moves. This is the single most important check on this page – and if your intact spring also has no cable, have cables installed during the repair; they are cheap and they are what stands between a future break and flying steel.
How Extension Springs Fail, Ranked
Most LikelyFatigue at the end loops. The open loop at each end of the spring flexes with every cycle and is the thinnest cross-section of the spring – it is where nearly every break we see lets go. Age and cycle count do the damage; the loop just picks the day.
PossibleCoastal corrosion. Extension springs are usually uncoated and mounted near vented, humid garage ceilings. Within a couple of miles of the water, rust pitting concentrates stress and shortens spring life by years.
Less CommonWrong spring for the door. A previous repair with an off-weight spring overworks both sides. The tell is a door that always slammed or always felt heavy since the last “fix.”
Do I Have Extension or Torsion Springs?
Look above the door opening: a single steel shaft with one or two tightly-wound springs around it means torsion – go to the broken spring guide. Long springs stretched alongside the horizontal tracks, one per side, mean extension – this page. Extension systems are typical of older Orange County homes and lighter single-car doors; many were never upgraded when the house was.
Can I Fix It Myself?
No – and with extension springs the reason is concrete: the springs must be matched as a pair to the door’s exact weight, stretched under load, and rigged with safety cables at the correct anchor points. Get the weight wrong and the door slams or flies; skip the cables and the next break is uncontained. The safe DIY contribution is exactly what the Next Step box says: identify, secure the area, and keep the opener off.
When to Stop Troubleshooting
Immediately – this page is diagnosis only. A visibly broken spring is a confirmed diagnosis, and everything after that point is professional work.
What a Professional Repair Involves
Both extension springs are replaced – the survivor has the same mileage as the one that broke – matched to the measured weight of the door. New safety cables are installed or replaced on both sides, pulleys and their bearings are inspected (worn pulleys are the hidden accomplice in most extension failures), and the door is balance-tested through its full travel. On older doors we will tell you honestly whether a torsion conversion makes sense: torsion systems last longer and fail less dramatically, but a healthy extension setup with safety cables is a perfectly good system. The visit typically runs about an hour – see spring replacement costs.
A Costa Mesa homeowner with a 1970s single-car door heard a bang and found a spring wrapped around the horizontal track – no safety cables anywhere on the door. We replaced both springs matched to the door’s weight, installed cables on both sides, and swapped two chewed-up pulleys while the tension was off. The homeowner had owned the house twenty years and never knew safety cables existed.
Frequently Asked Questions
What is the difference between extension and torsion springs?
Torsion springs mount on a shaft above the door opening and twist to lift the door; extension springs run beside the horizontal tracks and stretch. Extension systems are common on older and lighter doors, always work in pairs, and rely on safety cables to contain a break.
Can I replace just the broken extension spring?
You can, but you should not – springs are replaced in matched pairs. The surviving spring has identical age and fatigue, and a fresh spring paired with a tired one leaves the door unbalanced and brings you a second service call within months.
Are extension springs dangerous?
Under tension, yes – and a break without safety cables sends the spring halves wherever physics decides. With cables installed, the energy is contained. If your door has extension springs and no cables, that is worth a call this week even with nothing broken.
Related Problems
- Broken garage door spring – the torsion-system flagship guide, including cycle life and costs.
- Spring safety guide – why all spring work is professional-only, in depth.
- Is spring repair a DIY job? – the short answer with the reasoning.
- Cable came off the drum – the failure that often rides along with spring trouble.
This diagnostic guide was written and reviewed by our licensed garage door technicians (CSLB #994802), serving Orange County since 2013. The safety boundaries and repair guidance reflect what our crews diagnose and fix across more than 15,000 completed repairs and installations, rated 4.8★ by 1,000+ Orange County homeowners.
Broken extension spring? Same-day replacement in matched pairs, safety cables included – across all of Orange County.