On sectional garage doors, extension springs usually run above the horizontal tracks. They stretch as the door closes and contract to help lift it, counterbalancing the weight. One-piece doors can use a different spring-and-hinge arrangement. Both need correctly matched parts and safe containment; replacement is technician work.
How They Work on a Garage Door
As the door closes, cables pull the springs and stretch them along the track. That stored tension pulls back to help lift the door on the way up. Because they extend rather than twist on a shaft, a broken extension spring without a safety cable running through its center can come loose and become a projectile, which is why safety cables matter and why a technician checks for them on every job.
Signs of a Worn or Failing Extension Spring
- The door feels heavy or uneven to lift.
- Rust, a broken spring, or coils that remain distorted when they should have contracted. Normal extension springs have gaps while stretched.
- A loud bang, usually the spring letting go under tension.
- The door drops quickly instead of lowering evenly.
Why Replacement Isn't a DIY Job
Extension springs are under significant tension even before you touch them, and unhooking or rehooking one to change its tension uses the same technique as replacing it outright. A spring or hook that slips can release that tension suddenly. We match the replacement spring's length, wire size and safety cable to your door and confirm the door balances correctly once it's installed.
FAQ
How long do extension springs last?
Most are rated in cycles, one cycle being a full open-and-close, and typically last several years under normal household use. Salt air, humidity and lack of lubrication shorten that.
Can I replace an extension spring myself?
We don't recommend it. The springs are under enough tension to cause a serious injury if a spring, hook or supporting part slips while you're working with them.
Are extension springs or torsion springs better?
Torsion springs are more common on newer doors because they stay on their shaft if they break. Extension springs can serve sectional doors safely when correctly sized, maintained and fitted with the required containment cables. See our torsion spring guide for a comparison.
What does extension spring replacement cost?
It depends on the door's weight and how many springs and cables need replacing. See garage door spring replacement cost for what changes the price.
If your extension springs look stretched, rusted, or the door feels heavy, call (916) 838-8182. We replace extension and torsion springs across the Sacramento area, most often the same day, with a $45 diagnostic trip fee and the price agreed before we start. Spring replacement.
Photo: Tomwsulcer (CC0); resized and converted for this page. The photo shows a missing safety cable as a defect, not a recommended installation.
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