Why Replacing Only One Garage Door Spring Is a Big Mistake

We got a call from a house in the Chomedey area of Laval. The garage door, a big insulated 16-footer, was hanging crooked and jammed halfway up the tracks. The homeowner told us he’d had a spring replaced just six months ago. Now the other one snapped with a bang that shook the house. This isn't a surprise to us; it's a predictable outcome we see every week.

How a Paired Torsion Spring System Actually Works A garage door feels light enough to lift with one hand because of the torsion spring system, not the electric opener. The opener just replaces your muscle. The springs do all the real lifting. For a standard two-car garage door in Laval, which can weigh anywhere from 250 to 400 pounds depending on insulation and windows, a pair of springs is used. These springs are mounted on a steel tube above the door. As the door closes, the cables attached to the bottom corners rotate the drums at the ends of the tube, which twists—or “loads”—the springs. This stored energy, called torque, is what perfectly counterbalances the door's dead weight. When you open the door, the springs unwind and release this energy, lifting the door. The key is that both springs share this massive load equally. They are calculated as a team, designed to work in perfect unison. If one is doing more work than the other, the entire system is compromised from the start. That balance is everything, and it's the first thing to go when you replace only one spring.

The Predictable Lifespan of a Torsion Spring Garage door springs don't break randomly. They fail from metal fatigue, which is a direct result of use. The industry standard for a residential torsion spring is 10,000 cycles. One cycle is one full open and one full close. If you use your garage door four times a day, that’s about 1,460 cycles a year. At that rate, a standard spring will last roughly seven years. If two springs are installed on the same day, they experience the exact same number of cycles under the exact same load. They will therefore wear out and reach their failure point at almost the exact same time. When one spring snaps, the other one has maybe a few dozen, or at best a few hundred, cycles left in it. It has endured the same stress for the same duration. Leaving that old, fatigued spring in place next to a brand-new one is like putting one new tire on your car and expecting it to handle properly. The failure of the second spring isn't a matter of 'if,' but 'when'—and it's usually soon.

The Imbalance Problem: Mixing an Old Spring with a New One Here's the mechanical problem in plain terms. A brand-new torsion spring, let's say a common .250 gauge wire spring for a 16x7 door, is engineered to provide a specific amount of lift (measured in IPPT, or Inch Pounds Per Turn) when fully wound. The old spring on the other side, having gone through 9,900+ cycles, has lost some of its tensile strength. It's fatigued. It might look fine, but it's providing maybe 10-15% less lift than the new one. This creates a critical imbalance. The new spring is now trying to do more of the work, lifting its side of the door with more force. The old spring is a weak partner, dragging behind. The door no longer travels up the tracks smoothly. Instead, it twists. You can often see the top of the door lifting on the new spring's side a fraction of a second before the old spring's side starts to move. This twisting action puts enormous stress on every other component of your garage door system, from the rollers and hinges to the opener itself. It's a quiet problem at first, but it quickly leads to a cascade of other, more expensive failures.

On-Site Diagnosis: How We Spot a Mismatched Spring Job When we arrive at a home for our $29 service call, diagnosing a mismatched spring system is straightforward. First, for safety, we unplug the opener and pull the red emergency release cord to disconnect the door. We then try to lift the door by hand. A properly balanced door should feel relatively light (under 10 lbs of force) and should stay in place if you let go of it three to four feet off the ground. A door with one new and one old spring will often feel heavy and will drift down, or it might be “hot” and fly up on its own. It will almost never stay put. Next, we do a visual inspection of the springs. The new spring will be glossy black or have a clean galvanized finish. The old one will often have a duller finish, maybe some light surface corrosion, and a visible difference in the tightness of its coils compared to the new one. Finally, we get out our spring gauge and calipers. We measure the wire diameter, inside diameter, and length of both springs. It's not uncommon to find that a previous installer not only replaced one spring but used the wrong size, like pairing a .243 wire spring with a .250. This is a guaranteed recipe for failure.

The Damage Cascade from an Unbalanced Door Running a door with mismatched springs is like driving a car with the alignment way off. It's going to wear out other parts fast. The strain caused by the imbalance will systematically destroy your system. Here are the most common failures we see stemming from this single mistake:

• The main drive gear inside your opener, which is often a nylon composite part in many LiftMaster and Chamberlain models, will be chewed up and stripped by the excessive force needed to open a crooked, binding door.
• The steel lift cables fray and unravel because the door's twisting motion causes them to wrap unevenly on the cable drums (like a D400-8 drum common on 7-foot doors). A frayed cable will eventually snap, causing the door to fall.
• The door's rollers, particularly the standard 10-ball-bearing steel or nylon type, get ground down on one side of the door as they are forced sideways into the track, creating horrible grinding and scraping noises.
• The door panels themselves can be permanently damaged. The twisting force can pop the steel stiles off the inside of the sections or even cause the panels to crease or crack under the torsional load.
• The hinges connecting the door sections can bend or break because they are being pulled in directions they were not designed to tolerate.
• The end bearing plates, which support the torsion tube, wear out prematurely as the tube shifts and wobbles due to the uneven forces from the springs.
• The top fixture on the door, where the lifting cable attaches, can be pulled loose from the door section, especially on older doors where the steel may be weaker.

Montreal Winters and Salt: An Enemy to Springs In the Montreal area, our climate accelerates spring failure, making the single-spring replacement even more foolish. The extreme cold we get in January and February, with temperatures dropping below -25°C, makes the high-tensile steel of a spring more brittle and susceptible to fracture, especially when it's already near the end of its cycle life. Then there's the salt. All winter long, your car brings road salt and de-icing brine into your garage. This corrosive mixture gets kicked up onto the door components. For standard oil-tempered springs that only have a black coating, this salt spray dramatically speeds up rust formation. A rusty spring is a weaker spring, and it will fail sooner. Even galvanized springs aren't immune over the long term. This is why when we see one spring snapped due to a combination of fatigue and corrosion, we know its partner is in the same degraded condition. Replacing both with new, properly coated or galvanized springs is the only way to prepare the door for the next harsh winter cycle.

The Correct Fix: A Professional Dual Spring Replacement Doing the job right means replacing both springs and re-balancing the entire system. It’s a process that has to be done with precision. Here's what our technicians do on-site:

1. With the door in the down position, we clamp locking pliers onto the vertical track just above one of the rollers. This is a critical safety step to prevent the door from flying up unexpectedly once the broken spring is removed. 2. We carefully unwind any remaining tension from the old, non-broken spring using two proper steel winding bars. These are not screwdrivers or tire irons; using the wrong tool is how people get seriously injured. 3. Once all tension is gone, we unbolt the springs from the center anchor bracket. We then loosen the set screws on the cable drums, disconnect the lift cables, and slide the entire assembly of drums and old springs off the torsion tube. 4. We clean the torsion tube and inspect the center and end bearings for wear, replacing them if necessary. A worn bearing can impede the smooth rotation of the system. 5. We slide the two new, perfectly matched springs onto the tube. The red-cone spring goes on the left side, and the black-cone spring goes on the right. We re-install the cable drums. 6. We lock the tube in place and wind both springs to the correct tension, which for a standard 7-foot high door is usually between 7.75 and 8.25 full turns. We then tighten the set screws on the winding cones to 1/2-3/4 turn past finger-tight to lock them to the shaft. 7. Finally, we re-attach the lift cables, making sure they have equal tension. We remove the locking pliers and test the door's balance by hand. It must stay put at any point of travel. If not, we make fine adjustments to the spring tension until it's perfect.

High-Cycle Springs: A Smart Upgrade for Active Garages When we replace springs, we always give homeowners the option to upgrade from the standard 10,000-cycle springs. For a relatively small premium, we can install 20,000, 25,000, or even higher-cycle springs. This is one of the smartest investments you can make in your garage door. If your garage is the main entry to your home, like in many newer subdivisions in Sainte-Rose or Brossard, you could be using your door 8-10 times a day. At that rate, standard springs might not even last five years. High-cycle springs are not magical; the physics is simple. They are typically made from a slightly thicker wire gauge (for example, stepping up from a .250 to a .2625 wire) and are longer. The increased length means the steel doesn't have to twist as tightly to store the same amount of energy, reducing the stress on the metal with every cycle. This doubles or triples the lifespan of the part, saving you from another replacement job for 15-20 years instead of 5-7.

### Understanding Spring Specifications When you look at a spring, it's not just a random coil of wire. It has precise specifications that we use to match it to your door's exact weight, height, and track configuration. A typical spring might be described as `.250 x 2 x 32`. Here's what that means: `.250` is the wire diameter in inches. `2` is the inside diameter of the coil in inches. `32` is the overall length of the spring in inches. These three variables, along with the track radius (12" or 15") and drum size (e.g., D400-8), determine the spring's IPPT (Inch Pounds Per Turn) and its total lifting power. Using the wrong spring is just as bad as using a mismatched pair. A spring that's too weak will force your opener to do the lifting, burning out the motor. A spring that's too strong, or “hot,” will make the door hard to close and can cause it to fly open uncontrollably. Our trucks are stocked with dozens of sizes, and for custom or odd-sized doors, we use a digital scale and software to calculate the exact spring required.

Common Mistakes We Are Called to Fix We spend a lot of time fixing jobs done incorrectly by homeowners or unqualified handymen. When it comes to torsion springs, these mistakes are not just inefficient; they are extremely dangerous. The stored energy in a wound spring can cause serious injury or death if released improperly. Here are some of the most frequent blunders we encounter:

• Installing springs with the wrong wind direction, such as putting a left-wound (red cone) spring on the right side of the door. This spring will provide no lift at all.
• Using the wrong tools, like screwdrivers or pieces of rebar, to wind the springs. These can't handle the torque, and they will slip or break, turning into high-speed projectiles.
• Forgetting to properly tighten the set screws on the winding cones after winding the spring. The spring will spin loose on the shaft the first time the door is operated.
• Mismatched cable tension, which causes the door to close crookedly and can make a cable jump off the drum and get tangled.
• Replacing a two-spring system with a single, massive spring that wasn't designed for the door's hardware, putting immense stress on the center bracket and the torsion tube.
• Neglecting to check the door's balance after the installation. They replace the parts but leave the system dangerously out of tune, which puts the homeowner right back where they started with a strained opener.
• Guessing the spring size based on the old broken one, without accounting for its fatigue or the possibility that it was the wrong size to begin with.

Repair the Pair or Replace the Whole Door? The decision to repair springs or replace the entire door comes down to the condition of the rest of the system. If you have a 25-year-old uninsulated, non-gusseted steel door in an old Plateau laneway garage, and the bottom section is rusted through from salt and moisture, the panels are dented, and the rollers are shot, replacing the springs is a waste of money. The new springs will just be attached to a failing structure. In that case, we will be honest and tell you that your money is better invested in a new, modern insulated door, like a Garaga Standard+ (R-12) or a Clopay Gallery (up to R-18.4). However, if your door is a quality 10-year-old model that is in good structural shape, a dual spring replacement is a routine, cost-effective repair. For a fraction of the price of a new door, you are essentially restoring its core mechanical system for another decade of reliable service.

A balanced garage door is a safe, quiet, and efficient machine. That balance comes almost entirely from a correctly specified and installed pair of torsion springs working in unison. When one breaks, the system is broken, not just a single component. Changing both springs is the only professional way to do the job because it restores the system's integrity, protects your opener from strain, and ensures the door will function correctly for its next 10,000 to 25,000 cycles. It's the only way we do it, because it's the only way that works long-term.