Garage doors
Garage door springs explained, and why you shouldn't DIY them
Springs do the real lifting on a garage door — not the motor. Here's how they work, how long they last, how to spot a failing one, and why replacing them is dangerous without training.
Many people assume the motor lifts the garage door. In fact, a typical sectional door can weigh anywhere from about 70 kg for a single door to well over 150 kg for a wide double door, and the opener couldn't lift that on its own for long. The springs carry the weight. The opener just guides a door that is already balanced.
That's why a broken spring stops everything — and why springs deserve respect.
Two kinds of spring
Torsion springs are mounted on a steel shaft above the door opening. They are wound tight, and as the door closes they twist further, storing energy. When the door opens, they unwind and turn drums at each end of the shaft that wind up the lift cables. Most modern sectional doors use torsion springs.
Extension springs run alongside the horizontal tracks on each side, near the ceiling. They stretch as the door closes and pull as it opens, via pulleys and cables. They're common on older and lighter doors. Extension springs should always have a safety cable running through them, so if a spring breaks it can't fly across the garage.
Roller garage doors use a different system: a spring inside the barrel the curtain coils around, or a motor sized to lift the curtain directly.
How long do springs last?
Spring life is measured in cycles — one opening and one closing. Standard springs are commonly rated for around 10,000 cycles, and high-cycle springs are available for doors that are used a lot.
What that means in practice:
| Daily use | Cycles per year | Approx. life of a 10,000-cycle spring |
|---|---|---|
| 2 cycles | ~730 | 13+ years |
| 4 cycles | ~1,460 | ~7 years |
| 8 cycles | ~2,920 | ~3–4 years |
| 15 cycles | ~5,500 | under 2 years |
Large families with several cars, or a garage used as the main entrance, can easily reach 8–15 cycles a day. In those cases, high-cycle springs are worth the extra cost.
Signs of a broken or weak spring
- A loud bang from the garage, like a gunshot, when nobody was using the door. That is often a torsion spring snapping.
- A visible gap of several centimetres in a torsion spring coil.
- The door is suddenly very heavy or won't lift more than a few centimetres.
- The opener strains, hums or stops, or the door rises a little then reverses.
- The door lifts unevenly or one side is higher than the other.
- Slack or loose cables hanging from the drums.
A weak (not broken) spring is harder to spot. Do this test with the door closed: pull the opener's release cord and lift the door by hand to about half-way. A balanced door stays roughly where you leave it. If it drops down, the springs are losing tension. If it flies up, they're over-wound.
Why spring replacement isn't a DIY job
We say this as technicians who replace springs every week: please don't try this yourself.
- A wound torsion spring stores enough energy to break bones. If a winding bar slips, or the wrong tool is used, the spring unwinds violently.
- Cables and drums are under tension too. Loosening the wrong set screw can release them.
- An extension spring without a safety cable can snap and throw metal fragments across the garage.
- Springs must be matched precisely to the door's weight, height and drum size. The wrong spring leaves the door dangerously unbalanced, which also damages the opener.
Spring injuries are some of the most serious home-repair injuries there are. The cost of a professional replacement is small by comparison.
What a technician does
- Secures the door so it can't move while the springs are released.
- Measures the door and the old springs — wire size, inside diameter, length and wind direction — to select the right replacements.
- Replaces springs in pairs on two-spring doors. If one has broken, the other has done the same number of cycles and will usually fail soon.
- Checks and usually replaces cables if they're frayed or rusted, and inspects drums, bearings and rollers.
- Winds and balances the door, then tests it by hand.
- Resets the opener's limits and force, and tests the auto-reverse safety system.
While you wait for the technician
- Don't use the opener. It isn't designed to lift the full weight of the door and can strip its gears or pull its rail out of the ceiling.
- Leave the door closed if possible.
- Don't pull the release cord with the door open — with a broken spring, the door can drop suddenly.
- Keep people and cars clear of the door.
If you need a spring replaced, we carry common springs in our vans and usually complete the job in a single visit. See our garage door repair service.
