Garage door spring tension safety in Cranbourne - please, don’t DIY this one.

A garage door spring isn’t a spring in the household sense. It’s an energy-storage device, sized so that when the door is closed it stores enough torque to counterbalance the entire dead weight of the door panels - typically 80-120 kg on a double-car sectional. That energy doesn’t politely dissipate when something goes wrong. If a winding bar slips out of the spring cone during a wind-up, the spring unwinds completely in roughly 70 milliseconds. That’s faster than you can flinch.

The standard a torsion spring is wound to is roughly 7-9 quarter-turns past zero, which puts it in the 200-400 newton-metre band depending on door weight. For comparison, a plumber’s pipe wrench torquing a stuck fitting at full effort tops out around 150 newton-metres. The garage spring above your head right now is storing more than twice that - concentrated on a point you can’t see and can’t hear coming.

Why the lifecycle matters.

Builder-grade torsion springs in new Cranbourne estates (Clyde North, Botanic Ridge, the newer Cranbourne East subdivisions) are rated to roughly 10,000 cycles. One cycle is one full open-and-close. A family doing the school run, sport pickup, after-work shopping and the weekend hardware run is comfortably hitting 5-7 cycles a day, which puts the spring at end-of-life in 5-7 years. We see this constantly: estates that were turned over in 2018-2019 are coming up for first-spring-failure right now, in 2026.

When we replace, we standardise on 25,000-cycle commercial-grade springs. The install time is identical, the parts cost is about $40 higher, and the next failure window moves out to 15-18 years. The maths is so plain that we’ve made it a standard inclusion rather than an upsell - if you proceed with a spring job through us, you’re getting commercial-grade unless you specifically ask for the cheaper part.

• Wrong tooling: using a screwdriver or length of rebar instead of correctly-sized winding bars. The bar slips out of the cone, the spring unwinds, the bar becomes a projectile.
• No safety cables on extension springs: the cable is the difference between a snapped spring whipping along the track and a snapped spring contained by the cable. New construction often has them; older Hampton Park and Cranbourne West homes from the 1980s-90s frequently don’t.
• Door not secured to the track: when you unwind a torsion spring, the door wants to fall. If it’s not C-clamped to the vertical track on both sides, it drops on whoever is underneath.
• Working alone: if something does go wrong, there’s no one to call an ambulance or apply pressure to the wound. We always work in pairs on spring jobs for exactly this reason.

Identify your spring type before we arrive.

Send a photo of the area directly above the closed door to quotes@cranbournegaragedoorco.com.au and we’ll tell you which spring system you have before we leave the depot. Torsion springs are horizontal, mounted on a shaft above the door opening - one spring on a single-car door, two on a double-car. Extension springs run along the horizontal section of the track on each side, stretched when the door is closed. Tilt-door springs are at the rear corners of the garage, usually on older Cranbourne CBD and Hampton Park homes from before sectional doors became standard in the late 1990s.

How long does a professional spring replacement actually take?

30-60 minutes on a standard single-spring residential door, 60-90 minutes on a dual-spring setup or if the cables need replacing at the same time (which is often - cables fray during the period the door was operated with a broken spring). We diagnose, quote and complete on the same visit in 90%-plus of cases.

Should I replace both springs at the same time on a dual-spring door?

Yes. The springs were installed together, have done the same number of cycles, and have aged in the same conditions. Replacing one and leaving the other is a guaranteed return call-out within 12 months. A dual replacement is roughly $400-$800 fitted - less than two separate single jobs.

What if my door is still working but the spring looks rusty or stretched?

Visible rust along the coil isn’t cosmetic - it’s a stress riser, and that’s where the spring will fail. If you can see a gap that wasn’t there before, the spring is already partially failed. Stop using the door and call us. Continuing to operate strips the opener gear and can bend panels, turning a $300 job into a $1,500 job.

Are your spring jobs compliant with AS/NZS 60335.2.95?

Yes. AS/NZS 60335.2.95 is the safety standard for power-operated doors, and it covers the force limits the opener must respect, the obstruction-detection behaviour, and the safety-cable requirement on extension-spring systems. Every spring job we do is left compliant - safety cables fitted (or replaced if missing), opener force re-calibrated against the new spring tension, and obstruction reversal re-tested before we leave.