Why Garage Door Cables Come Off the Drum

On many doors a cable winds onto a drum at each end of the bar above the door. When the cable slips off the groove the door can no longer lift evenly. Here is what causes it.

Common causes

• A broken spring. The spring no longer holds tension. The cable goes slack and jumps the groove.
• A door that hit something. An object in the path or a car bump can knock the door and loosen a cable.
• A stuck or jammed door. If one side hangs up the cable on the other side can unwind.
• A worn drum or cable. Worn parts do not hold the cable in place.
• Poor setup. Cables that were fitted with the wrong tension slip more easily.

Signs to look for

• A cable hanging loose or bunched near the drum.
• A door that sits crooked.
• The door lifts on one side only.
• A cable that is wound unevenly or sits outside the groove.

Why you should not reset it yourself

Putting a cable back is not only a matter of dropping it into a groove. The system is under tension. A mistake can release stored force. It can also leave the door out of balance. A technician fits the cable and sets the tension and tests the door.

What about extension spring doors?

Doors with extension springs use pulleys instead of drums. The cable can slip off a pulley for similar reasons. Read torsion vs extension springs to see which type you have.

Next steps

Stop using the door. Read can you use a garage door with one cable broken if a cable has failed. Then call a technician. See our page on garage door spring repair.