One spring broke. The other one is exactly as old.
A two-spring Katy door does not have a strong spring and a weak spring. It has two springs that went up on the same morning, were wound to the same tension by the same installer, took an identical share of the load every single time the door moved, and sat through the same summers in the same garage. When one lets go, the other has done the same work and is somewhere inside the same narrow window of remaining life. The break is not evidence that one spring was defective. It is evidence that a matched pair reached the end of its service together, and one of them got there a few weeks first.
That is why the honest answer to can you just replace the one that broke is almost always no, and the reasoning is worth seeing rather than being asked to take on trust. Three things are true at once. The survivor is due, so a single replacement usually buys a second service call in the same season rather than a repair. The bill on a spring job is mostly the trip and the labor, not the steel, so the second spring costs far less inside a visit that is already happening than it does as its own visit later. And a new spring paired with a worn one does not share the load evenly — the fresh spring is stiffer, so it carries more than half the door and wears toward the same failure faster than it should, while the door itself sits slightly out of balance the whole time.
A single-spring door is a different conversation and we will say so on the phone. Some lighter single-car doors in older Katy sections were built that way from the factory, and on those there is nothing to pair.
What the spring took with it on the way down
A torsion spring stores a serious amount of energy, and it does not release that energy politely. The bang people describe as a gunshot is the spring unwinding in a fraction of a second, and the parts nearest to it absorb what is left. That is why a spring call is rarely only a spring call, and why a quote that lists other items is not automatically an upsell — though you are entitled to see the part and have the reason explained. Four things commonly come along with the break.
The cables. When tension vanishes the door drops and the lift cables go slack. Slack cable jumps off the drum, and once it is off it re-spools crossed or wedges between the drum and the bearing plate. A cable that has been pinched or kinked has lost strength at that point even if it looks intact, and cables are replaced in pairs for the same load-sharing reason the springs are.
The drums and the shaft. If the door fell far or fast, one drum can spin against the shaft or shift on its set screws, which leaves the two sides out of sync. A door that afterwards travels crooked, or that hits the floor on one corner first, is usually telling you the drums need to be re-seated and re-timed, not that the new spring is wrong.
The rollers and the top section. A dead-weight drop loads the rollers sideways and can flatten or seize the stems. If the opener was pulling when the spring let go, the force lands on the top section, because that is the only place the opener arm is bolted. A dimpled or bowed top section is worth catching during the spring visit rather than discovering later as a door that will not seal.
The opener. This one deserves its own explanation, because of how it usually gets damaged.
The opener is the part most often damaged after the spring — and it is damaged by a person
In most Katy households the garage is the door the family actually uses. Nobody walks around to the front. So the sequence after a spring breaks is nearly always the same: the door will not move, and somebody presses the button again to see whether it will move this time. Sometimes several times.
A residential opener is not a lift. It is designed to nudge a door that its own springs have already balanced to within a few pounds of neutral, which is why the manufacturers publish operator force limits rather than door weights, and why the industry hardware standards written by DASMA treat the counterbalance system and the operator as two separate systems doing two separate jobs. With the spring gone, that opener is being asked to drag the entire dead weight of the door. On a chain drive the nylon drive gear is the designed weak point and it strips, usually with a grinding noise and a motor that runs while nothing moves. On a belt unit the belt slips at the sprocket or frays. On a newer DC operator the force sensing usually saves the machine and it simply faults out and refuses — the best outcome of the three.
So if the door will not move, stop pressing. Pulling the red emergency release is the correct next step only when you understand that on a broken-spring door it hands you the full uncounterweighted weight of the door with nothing holding it up. Leave it down, leave it disconnected if it is already disconnected, and keep people and cars out from under it until it is repaired. If the door is stuck part-way open, that is not a wait-and-see situation.
None of this is unique to Katy in principle. What is Katy-specific is the frequency: a subdivision where the garage entry is the primary entry gets the extra button presses more reliably than a neighborhood where it does not, and we see the stripped-gear-plus-broken-spring pair on Katy calls often enough that we ask about it before the truck is loaded, so the right opener parts are on it.
How to read the quote, line by line
A spring quote should be legible to you without a trade background. A few things are worth knowing so that you can tell a complete job from a thin one, and a fair line item from a padded one.
Springs are quoted in pairs on a two-spring door for the reasons above, and the specification of what is being installed should be written on your invoice. Ask for that in writing. It is the single most useful thing on the paperwork, because it means the next person who touches the door — in ten years, possibly not us — does not have to take the door apart to work out what belongs on it.
Cables, bearings and the center bearing plate are parts, not symptoms. They wear on the same clock as the springs and they are cheap inside a visit that already has the shaft apart. If they are on the quote, they should be shown to you.
Balance and travel adjustment are labor, not a part. They should be included in a spring job rather than billed separately, because a spring that has not been balanced to the door has not been finished.
A new door is not a line item on a spring quote. If somebody arrives for a broken spring and leads with a replacement door, that is a sales call wearing a repair truck. There is a real case for a new door, described below, but it is a conversation to have with numbers in front of you and a night to think about it — not a decision to make standing in a hot Katy garage with the car trapped inside.
When replacing the spring is the wrong purchase
We will tell you when it is, because a repair that we know will not hold is worse for us than a job we did not take. Three situations come up.
The first is a door whose bottom section has rusted or delaminated from the inside out. The spring can be perfect and the door will still fail at the bottom, and the bottom section is the one that carries the cable brackets.
The second is a door whose sections are no longer made. That is a common ending for Katy doors of a certain vintage, and it is not really a spring question at all — we cover how to identify your door and what to do about it on our Katy panel replacement page.
The third is a door that has been repaired repeatedly around a problem that is not the spring: a track or opening that has moved, so the door binds and every counterbalance fitted to it wears out early. Our Katy off-track repair page covers how that presents and how to tell it apart from a spring problem.
Outside those three, a spring replacement on a structurally sound Katy door is one of the better repairs in the home — it restores the door to how it was built to work, it is done in one visit, and it costs a fraction of replacing a door that has nothing else wrong with it. That is the usual outcome, and we would rather do that job well than sell you out of it.
What we do not do on a Katy spring call
Stated plainly, so you can hold us to it. We do not fit a single new spring alongside a worn one and call the door repaired. We do not bill a paid visit to add a quarter-turn of tension to a spring that is at the end of its life, because that buys weeks, not years, and you will pay again. We do not quote a new door in place of a repair we are capable of doing. We do not charge separately for balancing a door we have just re-sprung. And if we open the door up and find that the real fault is somewhere else, we say so before we start — including when that means the job is smaller than the one you called about, or belongs to a different trade entirely.
