What is the difference between torsion and extension springs?

The difference is how and where they store the energy that lifts the door. A torsion spring is mounted on a metal shaft directly above the closed door and twists as the door moves, turning cable drums at each end of the shaft. Extension springs run alongside the horizontal tracks on each side and stretch as the door closes, then pull the door up through cables and pulleys when it opens.

How to tell which one you have

• Torsion: one or two large coiled springs on a bar above the door opening, with a drum at each end.
• Extension: long springs running parallel to the ceiling tracks on both sides, usually with a safety cable threaded through the middle.

Most garages built in the last few decades use torsion springs, and most two-car doors in our area have one or a pair. Older one-car doors more often use extension springs.

How they behave differently

• When one breaks: a torsion spring stays on its shaft. An extension spring relies on its containment cable to keep it from whipping loose, so that cable must be present and intact.
• Space: torsion systems need room above the door and have their own mounting and clearance requirements. Extension springs need room beside the tracks.
• Lift: because both sides of a torsion system are tied to one shaft, the door tends to lift more evenly.
• Lifespan: neither type automatically lasts longer. Life depends on each spring's cycle rating, sizing and condition.

Both need the right size

Either system works safely when the springs match the door's weight, height and hardware, and both are high-tension parts that only a technician should adjust or replace. If you are weighing a change, see whether to convert extension springs to torsion.

Read more

• Torsion springs guide
• Extension springs guide
• Garage door spring replacement

Related questions

• Can I adjust garage door spring tension myself?
• Should I convert my old extension springs to torsion springs?
• Can I replace a garage door spring myself?
• How long do garage door springs last?
• Why did my garage door spring break so soon?

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