Springs · · 2 min read
Why a snapped spring makes the door impossible to lift
The opener never lifted your door — the spring did. Here is the physics behind the one fault that leaves a garage door completely dead, and why forcing it makes things worse.
Most people think the motor lifts the garage door. It doesn’t. The motor — the opener — only pushes and pulls the last few pounds of a door that is already balanced. The thing actually carrying the weight is the wound steel spring above the door.
That is why, the morning the spring snaps, the door will not move at all.
The door was never as heavy as it is now
A typical sectional door weighs around 140 lb. You have never felt that weight, because a torsion spring stores it. Wound tight when the door is down, the spring pushes back with exactly enough torque to balance the panels hanging on the cables. Lift the door and the spring unwinds; as each panel rolls over the top and onto the horizontal track, its weight comes off the cables and the spring has less to hold. The two stay matched the whole way. A balanced door floats.
Break the spring and that balance is gone in an instant. Now the full weight hangs on the cables and the opener, neither of which was built to lift it.
Pull the red release cord and try to lift the door by hand a few inches. If it feels like lifting a fridge and slams back down, the spring is gone. A healthy door lifts with two fingers.
Why forcing it costs more
Running the opener on a dead spring
The opener will strain against 140 lb it was never rated for. You can strip its gears, bend the top panels where the arm pushes, or snap a cable under the sudden load — turning a single spring job into a spring, opener and panel job.
Leave the door closed. Don’t park a car behind it that you’ll need. Call a repairer who carries springs — the fix is usually same-day and the door is the only thing at risk if you wait.
What the repair actually involves
A spring is matched to the door: wire gauge, inside diameter and wound length all have to suit the weight. We measure, fit springs to match, wind them to the door’s own weight, and then balance the door so it floats at half-height before we leave. If your door has two springs, we replace the pair — they have done the same number of cycles and the second is rarely far behind the first.
We carry springs on the van
A dead spring is the job we prioritise. Tell us the make and rough age of the door and we’ll bring the right parts.