What the makers say about doing this yourself
Steel-Line's sectional door manual says spring forces are generally equal to the door's weight and are violently released if a spring breaks while wound or stretched, and its instruction is 'DO NOT ATTEMPT REPAIR'. It warns never to loosen any fastener on the spring assembly or bottom cable fixtures, and says lift cables should be changed only by experienced door people. B&D says garage door spring replacement is not a DIY task.
What garage door springs and cables do
The springs do the lifting. Steel-Line says a sectional door's weight can approach or exceed 200kg, yet B&D's Smart Pro manual says a healthy door should need no more than 20kg of force at the bottom rail. The gap between those two figures is the spring's work, and an opener is only steering what the spring holds up.
That is why a broken spring feels so sudden. The door hasn't changed. It has just stopped being held up, and the whole weight lands on the cables, the motor and anyone trying to lift it.
Which springs your door has
| What holds the weight | B&D's spring rating | |
|---|---|---|
| Roller door | Helical coil springs inside the drum above the opening | 30,000 cycles on Roll-A-Door |
| Sectional door | A torsion spring assembly above the door, with lift cables running to cable drums | 10,000 cycles on Panelift, 20,000 on Panelift Icon, with a 30,000 cycle option on Panelift Icon |
| Tilt door | Extension springs, which B&D says its Flex-A-Door tucks above head height and a tilt door doesn't | Not on B&D's list |
How long a garage door spring lasts
A cycle is one opening and closing, so the rating is a count of use, not years. B&D's own sum for a Roll-A-Door is five opens and closes a day for over 15 years. A Panelift spring rated at 10,000 cycles gets used up far sooner at that rate. If the garage is how your family comes and goes, that is closer to the real figure than any general answer.
Springs also fade before they fail. B&D's manual says it is natural for them to lose tension over time, so a door that has got slowly heavier may be telling you early. Near the sea, Steel-Line says rust commonly affects springs as well as hinges and tracks.
Signs a spring or cable is going
- A bang from the garage with nobody near the door
- A door that is suddenly much heavier, or won't lift at all
- The opener hums or labours and the door hardly moves
- A gap in a spring, or coils that look stretched
- One side lifting ahead of the other
- Frayed or broken strands on a lift cable
- A roller door that won't stay up, rolls up loosely or slams shut, which Steel-Line puts down to lost balance
What a garage door spring repair involves
The door specialist makes the door safe, takes out the failed part and fits one that suits the door. That match matters, because a spring is chosen to carry the door's weight. If insulation or anything else has gone onto the door since it was new, say so when they call.
Then comes the part you can't see. The door has to be balanced again, and Steel-Line says a professional rechecks the balance after setting a roller door's tension. If there is an opener, ask for the auto-reverse to be tested before they leave, because the door now moves differently from the way it did the day before.
Changing garage door cables
Cables look simple, and that is the trap. Steel-Line says they carry the full weight of the door and must be free of frayed or broken strands. They run to the bottom corners of a sectional door, where the fixtures hold back spring force, so this is one to look at from a distance and never undo.
B&D builds corrosion resistant stainless steel cables into its Panelift Icon, which is worth asking about near the sea. If a cable has snapped and the door is stuck, send it as stuck open or off its track so the door specialist sees that it is urgent. We can't say how soon they will get there, so read the broken spring guide and stay clear of the door.
What helps the door specialist on the first call
- Roller, sectional or tilt, and single or double
- Open, shut or stuck part way, and whether a car is inside
- Whether the door has had insulation or anything else added
- Roughly how many times a day it runs
- Any brand name you can see from the doorway
What you can do, and what to leave
You can
- Stop using the opener and keep everyone clear
- Take a photo from a safe distance
- Find the warranty and the date the door went in
- Leave the door exactly where it stopped
Leave to a door specialist
- Springs of every kind, on every door type
- Lift cables, cable drums and bottom brackets
- Tensioning and balancing the door
- Resetting the opener and retesting its safety features
What we would do
Ask what cycle rating the new spring has. If the garage is the way in and out of your home, a higher rated spring may suit better than a like-for-like swap, and B&D lists a 30,000 cycle option on its Designer Door and Panelift Icon. Not every door will take one, but the question takes ten seconds.