Garage door springs, explained — and why yours broke in January

Here is the thing almost everyone gets wrong about a garage door, and it is the most expensive misunderstanding in the trade: your opener does not lift the door. The springs lift the door. The opener is a positioning motor that nudges an already-balanced weight along a track. Once that clicks, everything else in this article follows.

The opener does not lift your door

A double garage door weighs somewhere between about 130 and 350 pounds depending on construction. A residential opener produces a small fraction of the pull needed to hoist that off the floor.

It never has to, because the springs are wound to counterbalance the door's weight almost exactly. A correctly balanced door is, in engineering terms, weightless in the middle of its travel. You can lift it with two fingers. The opener's actual job is to move a balanced object, hold it up there, and stop when something is in the way.

Which is why, when a spring breaks, the door does not simply become "a bit heavier." It becomes its full dead weight, all at once, with a motor attached that was never designed to lift it. Run the opener at that point and you will usually buy an opener as well as a spring — a stripped drive gear, a bent rail, a torn-out header bracket, or a top section pulled apart where the opener arm attaches.

Torsion springs and extension springs

Two systems. You have one or the other, and you can tell in three seconds.

Torsion springs sit on a steel shaft mounted horizontally above the door opening. As the door comes down, cables running from the bottom brackets wind onto cable drums at each end of that shaft, twisting the spring and storing energy. As the door goes up, the spring unwinds and returns it. Torsion is the modern standard. It is better balanced, quieter, kinder to the door, and it fails in a more controlled way.

Extension springs run horizontally along the inside of each horizontal track, above the door when it is open, and stretch as the door comes down. You still see plenty of them on older single-car garages across west Evanston and Rogers Park, and they work fine when they are set up correctly.

There is one non-negotiable point about extension springs: they must have safety containment cables running through them, anchored at each end. Without one, a broken extension spring becomes a length of steel travelling across the garage at speed. If you look up and see extension springs with nothing threaded through the middle, get containment cables fitted. It is a small job. It is also the single cheapest safety improvement available on an old door.

How a spring is specified — and why guessing fails

A torsion spring is defined by four things:

• Wire gauge — the diameter of the steel wire itself, which sets how much torque a given twist produces
• Inside diameter — the bore of the coil, which must match the shaft and the fittings
• Length — the overall wound length, which sets how many turns are available
• Wind direction — left-hand or right-hand. On a pair, one of each. Fitting two the same way round is a real mistake people make.

Those four numbers together produce a specific amount of lift. That lift has to match the weight of your door, not the weight of a door of that size in a catalog.

This is where most bad spring jobs go wrong. Two sixteen-by-seven doors can differ by eighty pounds depending on whether they are single-skin steel, insulated sandwich construction, or wood. Add a couple of struts, a set of windows, or a heavy overlay and the number moves again. A door that has had two sections replaced is not the weight it was when it left the factory.

So the honest method is to weigh the door — disconnect the opener, release the springs safely, and put the door on scales — or, where the paperwork survives, to work from documented construction. The dishonest method is to look at the size and fit whatever is on the van. That produces a door that either drifts down on its own or floats up when you let go, and either way the opener spends the rest of its life fighting.

Cycle ratings, and the arithmetic nobody does

Springs are rated in cycles. One cycle is one full open and one full close. Not one press of the button — one round trip.

A standard residential spring is rated around 10,000 cycles. Higher-cycle springs, made from heavier wire in a longer coil, are commonly available at roughly 20,000 to 50,000 cycles.

Now do the sum for an ordinary household:

Seven years is the number most Evanston families land on. That is why a door installed when you moved in fails at about the time you have stopped thinking about it — and why, if your garage is the family's main way in and out, paying once for a higher-cycle spring is usually the cheaper decision over the life of the door.

It also explains something people find suspicious: a spring that "only lasted six years" has very often done exactly what it was sold to do.

Why it broke in January

Three things stack up, and only one of them is the cold itself.

One: steel gets less forgiving as it cools. A spring near the end of its fatigue life has microscopic cracks propagating from stress concentrations in the wire surface. Lower temperatures make that final propagation more likely, so the spring picks the coldest morning. It was going to go regardless. Cold decided the date.

Two: freeze–thaw sticks the door to the slab. NOAA's 1991–2020 normals put the official Chicago station at 121 days a year with a low at or below freezing and 6.5 days at or below 0°F, with January averaging a high of 31.6°F against a low of 18.8°F. The daily swing crosses the freezing point through most of midwinter. Water melts at the threshold in the afternoon and refreezes overnight, and a hardened bottom seal bonds to the concrete. The opener then loads the whole system against a door that will not move.

Three: corrosion got there first. Road salt tracked into an unheated garage pits the spring wire, and every pit is a place a fatigue crack can start. We wrote that up separately in the road salt guide, because it is the part of the story most people have backwards.

Stack those and you get the pattern we see every year: a quiet December, then a week in January when half the town's springs go at once.

Why both springs get replaced, even though one broke

This is the recommendation that sounds like an upsell, so here is the reasoning laid out.

On a two-spring door, both springs were fitted on the same day, carry the same share of the load, and have turned exactly the same number of cycles. They are the same age and the same wear. When one fails, the other is not fine — it is the same distance through its life, and it simply has not got there yet.

• The second one follows quickly. In practice, usually within months.
• A new spring beside an old one is not balanced. The new spring is at full rated torque, the old one has relaxed with age. The door lifts unevenly, twists slightly in the tracks, and wears the rollers and the cables on one side faster.
• You pay the labour twice. Winding and setting a spring is most of the work, and it is the same work whether you fit one or two.
• The uneven load reaches the cables. An unbalanced door is one of the more common causes of a cable failing at the drum, which is a second call-out and a worse one.

If a technician offers to replace only the broken one, ask what the other one's remaining cycle count is. Nobody can answer that, which is the point.

Why this is genuinely not a DIY job

We are not going to be preachy about this, and we are deliberately not going to describe the procedure.

A torsion spring on an ordinary double door holds enough stored energy to kill someone. It is not "enough to hurt." When a wound spring is released without control, that energy leaves through whatever is nearest — usually the tool, and usually towards the person holding it.

The specific failure mode is worth naming, because it is the one that puts people in hospital. Winding a torsion spring requires properly sized steel winding bars that fit the winding cone correctly. Screwdrivers, rebar, drill bits and lengths of pipe are not winding bars. When an improvised tool slips or bends inside the cone, the bar does not fall out — it is ejected, at the speed of the spring unwinding, from about head height.

That is the whole argument. Not "call a professional." Just: the tool leaves your hands, fast, and you are standing in front of it.

The Consumer Product Safety Commission publishes safety information on garage doors and openers, and DASMA's technical guidance covers how door systems are meant to be set up and tested. Both are worth ten minutes of your time and neither will teach you to wind a spring, because that is not something you learn from reading.

How to tell in ten seconds whether the spring is broken

Stand inside the garage with the door closed and look up.

Torsion springs: look along the shaft above the opening. A working spring is a continuous, tightly wound coil. A broken one has an obvious gap of one to three inches in the middle of it, with the two halves separated. That gap is unmistakable once you know to look for it. Often the two ends have also rotated slightly out of line.

Extension springs: look along the horizontal tracks. A broken extension spring will be hanging visibly slack, or in two pieces, or one side of the door will sit obviously lower than the other.

What to do the moment you see it:

1. Stop using the opener. Not one more attempt.
2. Do not try to lift the door by hand. It now weighs its full dead weight with no counterbalance, and there is nothing holding it up if it gets away from you.
3. If the door is open, leave it open and keep everything out from under it. Do not "just close it quickly."
4. Move people, pets and the car clear of the door's path, and unplug the opener so nobody presses a remote out of habit.
5. Call. Broken spring replacement is a same-visit job with the right parts on the van, and it is the single most common call we get in this town.

Tired, not broken: the balance test

Springs give warning before they fail, and the warning is a change in balance. This test takes a minute and tells you more than any noise the door makes.

Other warnings worth acting on: a loud bang from the garage with no visible damage (that is usually the spring letting go, even if the door still moved that time), a door that has become noticeably heavier over a season, a visible gap opening in a coil, or one side of the door lifting ahead of the other.

Any of those means a service visit now rather than a call-out on the coldest morning of the year. And if the opener has already been strained against a stuck or unbalanced door, get the opener checked at the same time — a stripped gear and a frayed lift cable are the two things that most often turn one job into three.

If you are looking at a gap in a coil right now, call (224) 505-2236 and leave the door alone until someone arrives.

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