Garage Door Cable Came Off the Drum? Why It Happens and What to Do

Question 01

What do garage door lift cables and drums do?

On a sectional door, two steel lift cables run from the bottom corners of the door up to a drum at each end of the spring shaft. As the door rises, the cables wind onto the drums and the springs do the lifting. The cables, drums and springs work as one balanced system.

Garador's glossary of garage door terms describes it plainly. The cables connect the bottom corners of the door to the cable drums, and the drums sit at each end of the torsion spring shaft. The torsion springs wind up as the door closes and unwind to help it open, and the cables carry that lifting force down to the door.

Each drum has grooves cut around it. Patent documents for these drums explain that the grooves guide the lift cables on and off the drum and stop the coils rubbing against each other or piling on top of one another. When the cable sits neatly in those grooves, both sides of the door lift at the same rate.

This guide is about sectional (panel-lift) doors. Roller doors work differently: the whole curtain rolls up around a drum above the opening, with the springs inside. If a roller door has gone heavy or unravelled, see heavy roller doors and spring tension.

Question 02

Why did my garage door cable come off the drum?

Usually because the cable went slack. A patent on cable slack detection notes that even a small amount of slack can let cable windings leave the drum. Slack can come from a broken or weak spring, a door that jams while the drum keeps turning, a drum that has slipped on its shaft, or cables that weren't wound till taut.

The jammed-door cause is the one people miss. A US patent on cable slack detection describes a door stopped by an obstruction while the operator keeps unwinding cable. Once the obstruction is cleared, the door can fall suddenly because the cable has gone slack. That patent is written about commercial door operators, but its general point is that even a small amount of slack can let cable windings leave the drum.

The drum and cable faults come from the troubleshooting table in B&D's Panelift installation manual. The remedies B&D gives for these cable faults all mean loosening the cable drums, rewinding the cables or checking spring tension, which is installer work, not owner work.

Question 03

How can I tell if the cable came off the drum or snapped?

Look from a safe spot without touching anything. A cable off the drum is usually still in one piece but hangs loose or tangled near the top corner. A snapped cable is in two pieces. Either way the door is out of balance and needs a technician.

• Cable off the drum: the cable is whole but slack, looped or wrapped around the shaft beside the drum instead of sitting in its grooves.
• Snapped cable: a cut-off end hanging from the drum or lying on the floor, sometimes with frayed strands near the break.
• Door hanging crooked: one side higher than the other. B&D lists cables that aren't equally taut as a reason a door won't sit level.
• Door jamming or rubbing in its tracks: B&D's Panelift troubleshooting lists slipping lifting cables and a cable drum not lined up correctly among the causes of door panels jamming or rubbing on the tracks.

Take a photo from where you're standing if you can see the drum. It helps Thom know what he's walking into. If the door is also off its tracks, garage door won't open or close covers what else can cause that.

Question 04

What should I do when a garage door cable comes off the drum?

Stop using the opener, leave the door where it is and keep people, pets and cars out from under it. Don't pull the red release cord if the door is open, because a door with a slack cable or weak spring can fall fast. Then call a technician and describe what you can see.

1. 01Stop pressing the remote. Merlin's opener manual says not to let the opener make up for a door that is binding or sticking. B&D adds that running a door with a broken spring can strain the motor, cables and tracks and raises the risk of it slamming shut.
2. 02Leave the door where it is. Shut stays shut. Open or half open stays put, with everyone kept clear.
3. 03Leave the release cord alone on an open door. Merlin's manual release guide warns an open door may fall rapidly when the springs are weak or broken.
4. 04Call 0402 882 653. Booked work runs 7 days, 6am to 6pm, and Thom takes 24/7 emergency callouts across the Sunshine Coast.

The full set of safe steps for a broken spring or cable, including what to do if your car is stuck inside, is in broken garage door spring or cable: what to do right now.

Question 05

Can I put the cable back on the drum myself?

No. It isn't a re-thread job. The cable has to suit the spring tension, and the springs are under heavy load the whole time. B&D's installation manual warns that too much cable on the drum will affect the spring tension, and B&D says spring replacement should be left to a qualified technician.

Online videos make rewinding look quick. What they skip is that the cable and the springs are one system. B&D's Designer Series installation manual says there must be no more than one turn of cable around the drum, and that too much cable will affect the spring tension. Get the wind wrong and the door lifts crooked or out of balance.

A cable often comes off because a spring has failed, so the spring may be the real fault. B&D is blunt in its broken spring safety guide: spring replacement is not a DIY task, because the tension involved makes it dangerous. Spring and cable repairs are booked as a normal callout.

Question 06

What about a garage door cable that has come off a pulley?

Some doors run their lift cables over a pulley wheel rather than straight up to the drum. A cable off a pulley has gone slack in the same way as one off a drum, and it's just as tied to the spring tension. Treat it the same: stop using the door, keep clear and call.

Pulleys turn up in a few layouts. B&D's Panelift installation instructions describe a rear torsion setup for low-headroom garages, where each lifting cable runs around a pulley wheel and back to drums at the rear. Separately, B&D's garage door springs guide says extension springs are found in older or tilt-door systems and carry a higher risk if they snap without safety cables.

Whatever the layout, a cable that's left its pulley or drum means the door is no longer held evenly. Don't lift it by hand to take the weight off, and don't try to lever the cable back into the groove.

Question 07

How is a cable that came off the drum repaired?

The technician finds out why the cable went slack, then replaces or refits the cable and sets the spring tension so both sides lift level. On Deadlock jobs, Thom replaces frayed or snapped cables, checks the drums and bottom brackets they hook onto, then resets the door so it lifts level.

1. 01Find the cause. A slack cable usually has a reason, so the springs, drums and bottom brackets get checked, not just the cable.
2. 02Fix the cause and the cable. A frayed or snapped cable is replaced. While the door is apart, Thom checks the cables and drums that work alongside the spring.
3. 03Set the balance and test. Merlin's opener manual says a properly balanced door will stay at any point of its travel while supported by its springs. Then the door is reset so it lifts level.

Repairs and servicing are booked as a callout valued between $200 and $300, depending on the door size and the labour involved. Thom has 3.5 years of hands-on experience and has trained across multiple garage door brands, systems and businesses. Other faults are covered on garage door repairs, or you can book a callout.

Question 08

Why does my garage door cable keep coming off?

A cable that keeps coming off the drum has a cause that hasn't been fixed. Common ones are a weak spring that no longer keeps the cable tight, a drum that has slipped or sits out of line, or cables that weren't wound till taut. Putting the cable back without fixing that cause means it will come off again.

B&D's Panelift troubleshooting table lists slipped cable drums and cables not wound till taut as causes of loose lifting cables, and a cable drum not lined up correctly among the causes of a door rubbing on its tracks. Each remedy means loosening the cable drums and rewinding or realigning the cables, so it's a garage door repair rather than a quick reset.

Regular servicing gives a slipping drum or tired cable a chance to be caught early. B&D's standard service lubricates the cable drum and tightens cables and connectors, and B&D recommends a service in the first 12 months and every two years after that, according to its support FAQs. A Deadlock garage door service includes a cable and drum inspection, where frayed or rusty strands get picked up before one snaps. Deadlock suggests booking every 6 to 9 months if the door runs many times a day, or sits close to the beach, a river or a canal.