Garage Door Cables: Warning Signs and Why Not to DIY Them

Cables are easy to overlook. They are thin, they run along the sides of the door, and they rarely make noise until something goes wrong. But they're part of the system that holds the door's weight, and a failing cable can let a door drop or jam at an angle.

Here is what they do, what to watch for, and what to do if something looks off.

What garage door cables do

Most residential doors use one of two spring setups. With torsion springs, which sit on a bar above the door, a lift cable runs from each bottom corner of the door up to a drum on that bar. As the springs turn the bar, the drums wind the cables and lift the door.

With extension springs, which run along the horizontal tracks on each side, the cables run through pulleys and help the springs lift the door. Those springs should also have a safety cable threaded through the middle to contain the spring if it breaks.

Either way, the cables and the springs work together, and they are both under tension.

Warning signs to look for

You can check for most of these just by looking, with the door closed. Don't touch or pull on the cables.

• Fraying or broken strands. Look near the bottom brackets at each corner of the door. That's where cables often wear first.
• Rust. Moisture, especially near the floor, can corrode cables and weaken them.
• Slack. A cable that looks loose, or one side that looks looser than the other, is a red flag.
• Off the drum or pulley. On torsion systems, the cable should wind neatly in the grooves of the drum. A cable jumping out of its groove or hanging off is a problem.
• A crooked door. If one side sits lower than the other, or there's a gap under one side when closed, a cable may have slipped or broken.
• Jerky or uneven travel. The door shudders, tilts or binds as it moves.
• A loud snap. A cable or a spring breaking can make a sharp bang.

What to do right away

• Stop using the door, both the opener and by hand.
• If the door is open, leave it open. Don't try to force it closed.
• Keep people, pets and cars clear of the door.
• Don't pull the manual release on a door that is open and crooked, since the door may be very heavy on one side and could fall.
• Call a professional and describe what you see.

If a car is stuck in the garage, ask the professional how soon they can help. Forcing the door usually makes the damage worse.

Why cables are not a DIY repair

The cables connect to the bottom brackets at the corners of the door, and those brackets are tied to spring tension. Loosening the wrong bolt, or unwinding a cable on a system that is still under tension, can release that energy suddenly. That can mean a spinning bar, a whipping cable or a falling door.

Doing it right takes the correct tools, a way to take tension off the springs safely, and experience with the specific setup. For the same reasons, springs are also a job for a professional. Our guide to spring warning signs covers that side of the system.

What wears cables out

Cables wear with use, like any moving part. A few things speed that up: moisture and rust near the floor, rollers or tracks that are worn or out of line and let the door move unevenly, and a door that's out of balance, which can put uneven load on the cables.

A yearly inspection catches most cable wear before it becomes a failure. A good visit looks at cables, drums, pulleys and bottom brackets, along with the springs and door balance. You can see the full list in what a garage door tune-up actually checks. And for everyday habits that keep your family safe around the door, read garage door safety every family should know.