The short version: a residential garage door weighs 150 to 250 pounds. Torsion springs mounted above the door store mechanical energy when they are wound, and release it gradually to counterbalance that weight as the door rises. Standard residential springs are rated for 10,000 cycles. Heavy-duty replacements run 25,000 to 30,000 cycles. They almost always fail with a loud bang, usually when the door is closed and the spring is under maximum tension. On the Georgia coast, salt air can shorten spring life by 20 to 30 percent. Replacement should always be done by a tech with a winding bar. Here is why.
How a Torsion Spring Actually Works
A torsion spring is a tightly coiled steel spring mounted on a steel shaft above your garage door. When the door closes, the spring is wound tighter, storing energy. When the door opens, the spring unwinds, transferring energy through cable drums and lift cables to the bottom of the door. The opener motor does not actually lift the door. The spring does. The opener motor provides the small additional force needed to overcome friction and get the door moving. This is why a door with a broken spring feels like 200 pounds when you try to lift it, and why a broken-spring door will burn out an opener in a few cycles if you keep trying.
Cycle Ratings: 10K, 25K, and Why It Matters
A spring's life is measured in cycles. One cycle is one full open plus one full close. Standard residential springs (the kind that came with most builder-grade doors) are rated for 10,000 cycles. At four cycles a day, that is just under seven years. Heavy-duty replacement springs run 25,000 to 30,000 cycles. At the same four cycles a day, that is 17 to 20 years.
The difference in cost between standard and heavy-duty springs at install is roughly $40 to $60. The difference in service life is more than a decade. We default to heavy-duty springs on every replacement because the math is not close.
Why We Replace in Pairs
Doors wider than 9 feet (most modern two-car doors) have two torsion springs working together. When one spring breaks, the other one is the same age, has the same wear, and is days or weeks from breaking too. Replacing just the broken spring is like replacing one bald tire and leaving the other three. The labor cost is the same whether we replace one or both, because the door has to be unwound either way. Replacing the pair adds about $90 in parts and zero in labor.
Why Springs Break
Three things kill springs:
- Cycles. Every wind-unwind cycle adds microscopic stress. After enough cycles, the steel fatigues and snaps. This is the most common cause.
- Corrosion. On the Georgia coast, salt air pits the spring steel and accelerates fatigue. We see springs fail at 6,000 cycles in coastal homes that would have lasted 10,000 inland. Galvanized springs help. Stainless springs are overkill for residential but used on commercial doors near the water.
- Cold snaps. Steel under tension is more brittle when cold. The first really cold morning of the year, our phones ring all day with broken-spring calls. Coastal Georgia is mild, but a January morning at 28°F with a door under load is when the existing fatigue cracks finally let go.
The DIY Safety Warning
We hate to be the people who say "do not try this at home," but on torsion springs we mean it. A wound residential spring stores about 400 to 600 foot-pounds of energy. If a winding bar slips or you use the wrong tool, the spring will release that energy in a fraction of a second, into your face, hand, or shoulder. Emergency room records for garage door spring DIY are not pretty. Broken jaws, lost teeth, and broken hands are the common injuries. Permanent eye injuries happen. Even YouTube tutorials by experienced installers carry warnings.
The right tools for spring work are two correctly sized winding bars (not screwdrivers, not rebar), a vice-grip clamp on the shaft to prevent unintended rotation, and a torque wrench to set tension. Most homeowners have none of these. The total replacement cost for a pair of heavy-duty springs is usually $260 to $360 installed, parts and labor. Set against the medical risk, it is the easiest "call a pro" decision in home repair. Read our companion post on why hiring a professional matters for the rest of the safety picture.
When To Call
If you hear a loud bang from the garage and the door now feels heavy, the spring broke. Do not run the opener. Call (912) 209-4079. We carry standard and heavy-duty springs in every truck and most repairs are done in an hour. We cover Brunswick, St. Simons, Jekyll Island, Savannah, and the rest of the corridor. Full pricing and warranty details on our garage door spring repair in Brunswick page.