Torsion and Extension Springs, Explained
Springs are the heart of a garage door. They counterbalance its weight so the door can be lifted by an opener or by hand. Knowing which kind you have and how they wear makes it easier to understand a repair estimate.
What springs do
A typical double garage door is heavy, far more than most people could lift easily. Springs store energy as the door closes and release it as the door opens, so the door feels light. When springs are working and adjusted correctly, the door is balanced: it stays put when lifted halfway by hand. The opener only has to guide it.
Torsion springs
Torsion springs sit on a steel shaft mounted above the door opening. As the door closes, cables wound on drums at each end of the shaft twist the springs tighter. As it opens, the springs unwind and turn the drums, lifting the door. Most newer homes around Boise use torsion systems. They tend to give smoother, more controlled movement, and a broken torsion spring usually stays on its shaft.
Single-spring setups are common on lighter single doors; two springs are common on double doors. When one of a pair breaks, the other is the same age, so many repairs replace both.
Extension springs
Extension springs run parallel to the horizontal tracks on each side of the door and stretch as the door closes. They are common on older and lighter doors. Because a broken extension spring can fly, they should always have a safety cable running through the center of each spring, anchored at both ends. If you see extension springs without safety cables, that is worth fixing.
How to tell which you have
- A coiled spring (or two) on a bar above the door: torsion.
- Long springs running along the tracks near the ceiling on both sides, with pulleys: extension.
- Some newer doors have enclosed torsion tubes; the springs are inside.
Cycle ratings
Springs are rated by cycles, where one cycle is one open and one close. A busy household that uses the garage as the main entrance can go through many cycles a day. Higher-cycle springs cost more up front but last longer. Ask what rating an estimate includes.
Signs of wear
- The door feels heavier when lifted by hand or will not stay halfway up.
- Gaps or stretched-looking coils.
- Rust on the coils.
- The opener strains or the door moves unevenly.
Cold weather can be the last straw for a fatigued spring, and Treasure Valley winters regularly bring nights below freezing according to NOAA normals (NOAA NCEI U.S. Climate Normals).
Why spring work is dangerous
Springs hold a lot of stored energy. The U.S. Consumer Product Safety Commission warns about injuries from garage doors and their hardware (U.S. Consumer Product Safety Commission, garage doors and openers). Winding a torsion spring takes proper bars and know-how, and loosening a bottom bracket or cable under tension can release that energy suddenly. See broken spring repair and what shapes spring work.
Related pages: broken garage door spring repair, off-track door & cable repair, garage door repair, and what shapes an estimate.
Sources: U.S. Consumer Product Safety Commission, garage doors and openers; NOAA NCEI U.S. Climate Normals.
Short answers
Which spring type is better?
Torsion systems are common on newer homes and usually run smoother. Extension systems work well on lighter doors when they have safety cables.
Can I convert extension springs to torsion?
Often, yes. It involves new hardware and should be scoped in writing.
Why replace both springs?
They are the same age and have done the same work. The second often fails soon after the first.
Do springs need maintenance?
A light coat of garage door lubricant and an annual balance check help.
Related garage door work
Broken Garage Door Spring Repair
Torsion and extension spring replacement for doors that will not lift, with notes on cycle ratings, matching pairs and safety.
Off-Track Door & Cable Repair
Doors that have come out of their tracks, hang crooked or have a snapped or loose lift cable, put back safely and checked for bent parts.
Garage Door Repair
Noisy, slow, sagging or stuck doors: rollers, hinges, bent sections, seals and balance, fixed before small problems wear out the opener.
More to read
- Garage Door Safety Sensors and Auto-ReverseHow garage door photo-eye sensors and auto-reverse work, the CPSC monthly test, why doors reverse unexpectedly, and how to keep kids and pets safe.
- Heat, Cold and Garage Doors in the Treasure ValleyHow Boise-area summer heat, winter cold, inversions, wind and dust affect garage door springs, seals, lubricant, openers and insulated doors, with…
- Repair or Replace a Garage DoorHow to decide between repairing and replacing a garage door around Boise: age, damage, insulation, parts availability, opener condition, HOA rules…
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