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I have garage door with two springs. One of them has snapped and the door has been operating on only one spring for past month or so.

Do I need to replace the broken one or just carry one since it’s operating on one spring?

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  • There are two main types of garage door springs: extension and torsion. Extension springs are pretty straight forward and not to hard to do. I've done mine twice. Torsion springs can be dangerous if you are not careful, hence some of the comments and answers below. You have not identified your type, nor shown any pictures, so some of the given answers are irrelevant to your situation.
    – DaveM
    Mar 24 at 20:20
  • That depends. Do you like being alive?
    – Ian Kemp
    Mar 27 at 8:40

7 Answers 7

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You must replace both springs.

Avoid using the door until you do. You must replace them with the correct springs which are color coded according to door weight. You must weigh your door and not rely on the old ones being correct.

If your springs are the kind hanging over the rails and stretch out straight when opened you must thread the retaining cables correctly, whether or not they are currently installed. Lots of YouTube tutorials on all this. Watch several. There are a lot of dangers to be aware of.

If your springs are coiled over the door frame they are even more dangerous and you should get a pro to do the work. It's not worth learning this once in 15 years skill given the dangers.

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    "It's not worth learning this once in 15 years skill given the dangers." This. I have an over-door spring system. When a support cable snapped I got as far as reading "Warning: these springs can take your fingers off" before deciding to get a pro in. And in 30 years of living in this house I've had this done twice. A popular modification with my neighbours is to replace their up-and-over doors with electrically operated roller shutter doors.
    – Graham Nye
    Mar 24 at 16:57
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Close the door, then unhook the power garage door opener immediately! Start operating the door manually.

That will answer your question right away about whether the door is seriously broken. "Yes!"

Garage doors are dangerous. The door and the spring store a lot of energy and they can kill you. This is not for DIYing unless you learn the risks and take proper precautions.

The spring is really a counterweight. The door is supposed to feel weightless to the operator (you only have its mass to contend with). With half the spring gone, the door will "weigh" 50% of its actual weight. That means it will drop like a guillotine, with half the force it would drop with no spring at all. The only reason you don't know this is the power opener is hiding reality from you :)

There isn't extra spring there, it's not redundant or a backup. The spring must be balanced or the door would fly upwards. I had a door do that once when I set the spring too tight :)

Use the numbers on the old springs to order 2 new springs. The 2nd spring doesn't owe you anything. Replacing them is a bit of a job, the main thing is know what you're doing when winding and unwinding them.

Set the spring tension evenly so one spring isn't doing most of the work. The spring is correct when the door is happy in any position up or down. If near the bottom it creeps upward or downward, it's not set right yet.

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    "power garage door opener immediately" - he doesn't say he has a power door opener. As a DIYer, I've replaced springs on a garage door. It wasn't easy, but I don't want to do it again. My issue was the 2 springs had to go in a certain way, one way, the springs were silent, but the other way, they rubbed against each other and created a racket every time you opened the door. It was too much faff to take the springs off again, so it stayed like that for 5 years until we sold the house.
    – Neil
    Mar 24 at 9:39
  • "winding and unwinding them" Not all garage door springs are torsion. Some are standard compression/extension springs. My original garage door (self-installed) had compression springs. The replacement door had torsion springs. I was MUCH more comfortable installing the first set of springs - that was, frankly quite easy. Installing and adjusting the torsion springs was a bit nerve wracking. I called in a pro to do an adjustment a few years later when I had other issues to resolve, too. +1 anyway.
    – FreeMan
    Mar 24 at 13:40
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    @Neil it's a pretty safe bet that the OP has an opener. If he was operating the door by hand, the answer would be pretty obvious. ;)
    – FreeMan
    Mar 24 at 13:44
  • Well this part about the door feeling weightless feels weird to me. When I was a kid, the house I lived in from around age 3 to age 14 had two (pretty beefy) extension springs. No motor, so it required manual (hand) lifting and lowering. It was a heavy door and it was hard to lift it even with the springs. I could do it, my mother could not.
    – Michael
    Mar 26 at 20:58
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    @Michael think of it like this. On the railroad, they have these little "larry carts" maybe 5' x 6' with railroad wheels on roller bearings. Imagine you have a bundle of railroad ties on one on flat track, so 5000 lbs for all of it. It's easy to push it around, it's essentially frictionless, but the mass makes it resist changes in velocity. A well-tuned garage door is exactly like that. Placed at any height it should just stay put, being no harder to move upward than downward. Gravity is fully counterbalanced.
    – Harper - Reinstate Monica
    Mar 26 at 22:23
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Garage door sprigs are dangerous.
They have enough force to keep the door up, and garage doors are heavy, otherwise they would not need springs in the first place. You do not want a tensioned spring flying in your face when you do something wrong.

For your own safety, consider calling local shop that installs garage gates, they will be happy to install new springs for you. They are trained to do this, have access to parts, have proper tools, and know how to tune the tension so door opens flawlessly.

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The door was designed to work with two springs to balance the lifting and lowering force. With just one spring, those forces are increased. If you have a garage door opener and it's still working, it will burn up faster. If the door is manually operated, it will be much harder to open and the weight when closing it could be dangerous. You need to have the springs replaced for safety reasons.

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    The force involved isn't just "doubled". Strings would typically relieve about 80-95% of the force required to operate the door; one spring would relieve about 40-47% of the force. Thus, the amount of force required to operating the door would go from 5-20% of the door's weight to 53-60% of the door's weight.
    – supercat
    Mar 25 at 19:28
  • @supercat What are the strings you're referring to?
    – JACK
    Mar 25 at 21:06
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I'm mildly surprised that your door doesn't jam, since one side will tend to be lower than the other, due to some "play" in the joints... Also, if one broke, the other is soon to follow, so you might as well just have replacement episode, instead of two.

And, given my own experience, as in some other answers, doing it yourself is, first, dangerous, and, second, easy to mess up. :)

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The purpose of the springs is to take the weight off the garage door motor. Disconnect the chain drive by pulling on the rope while holding the door from slamming down. Now try to lift/or lower the door with one hand. If you can not do it, your motor is suffering. If you are lucky and have strong motor like 3/4 HP (normal is 1/2 HP) it will handle it for a while.

Replacing the spring is not DIY work even if it looks simple. First you will need special tools for the tension adjustment. There is a lot of energy stored in the spring and it can kill you.

How it works (images from Amazon)

tension

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You should replace the broken one.

They are designed to operate as a pair, meaning the remaining spring is double-stressed at lifting the whole door by itself, or the one good spring is pulling on one side of the door, making the door lopsided as it goes up and down, leading to extra wear and further damage to the mechanism.

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  • reason for downvote?
    – Triplefault
    Mar 24 at 12:13
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    Probably for the last paragraph. They're not designed as a fail safe. The door is designed to have both springs there. It's currently only "working" because the door opener has enough oomph to lift the door with only 1 working spring. (I presume there's an opener because the OP wouldn't be asking the question if he was opening it by hand.)
    – FreeMan
    Mar 24 at 13:42
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    It's actually highly likely since both springs are probably the same age, and subject to the same force and wear, that if one of them just broke, the other isn't far behind, especially if it continues to be used because it's now doing twice the work with the other one broken.
    – Darrel Hoffman
    Mar 24 at 16:04
  • Thanks! The second paragraph was part of a liability concept I took out, and forgot to take the rest out. Will edit.
    – Triplefault
    Mar 24 at 17:43
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    @DarrelHoffman: I don't think the amount of force on either spring would be affected by the presence or absence of the other, unless one attempted to adjust the surviving spring to re-balance the system, which would dangerous even if that spring was in perfect new condition.
    – supercat
    Mar 25 at 19:31

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