Cable trouble
What the lift cables do
Every sectional garage door has two lift cables, one on each side. Each cable is a braided steel wire. One end attaches to a bracket at the bottom corner of the door, and the other end winds onto a drum at the end of the spring shaft on a torsion system, or connects to a pulley arrangement on an extension system.
When the spring system supplies lifting force, the cables carry that force down to the door. As the door goes up, the cables wind onto the drums. As it comes down, they unwind. Because the cables are always in tension when the door is closed, they are among the most highly loaded parts of the entire system.
A cable is simple, but it is a part that is easy to overlook. It sits close to the door edge, partly hidden behind the track, and many people only notice it when something goes wrong. Knowing where it runs makes it easier to describe a problem accurately.
If you want a fuller explanation of how the drum and cable work together, read how cables and drums work.
How fraying starts
Steel cable is made of many thin strands twisted together. Over thousands of door cycles, those strands rub against the drum grooves, bend around the drum, and flex where the cable meets the bottom bracket. Eventually, some strands begin to break, and the broken ends stick out as tiny wires.
Moisture speeds this up. In a humid climate like Greater Houston, a cable can pick up surface rust, and rust makes strands brittle and rough. Garages that take on water during heavy rain, or doors whose bottom seals have failed, can expose the lower cable end and bracket to repeated wetting.
Misalignment adds wear. If the cable does not sit in the drum groove properly, or if the door rides unevenly, the cable can rub against the edge of the drum or the track. A cable that has been pinched, kinked or struck by a vehicle will wear out sooner still.
The result is a cable that looks fuzzy, frayed or thinner in places. It may still hold for a while, but it is weaker than it looks, and it can fail with little warning.
Where to look without touching anything
Start at the bottom of the door on each side. The lower bracket is a metal plate near the floor, and the cable attaches to it. Look at the loop or fitting where the cable connects. Frayed strands, rust staining or a cable that has pulled partly out of its fitting are red flags.
Then follow the cable upward along the edge of the door toward the drum or pulley. On a torsion system, the drum is a grooved wheel at the end of the shaft above the door. The cable should sit neatly in the groove and wind in a clean line. If the cable is bunched, loose, or sitting outside the groove, that is worth reporting.
Compare the left side and the right side. They should look similar. A cable that is slacker, shorter or more worn than its twin tells you something has changed. Also look at the door itself. One corner sitting lower than the other, or a door that looks twisted when open, can point to a cable problem.
Do all of this from a safe distance. Use your phone camera to zoom in rather than reaching toward the bracket. The cable is under load whenever the door is closed, and a snapped cable can whip violently.
- Fuzzy or broken wire strands near the bottom bracket.
- A cable that hangs loose or looks slack on one side.
- Rust staining or flaking on the cable or fittings.
- A cable sitting outside its drum groove.
- A door corner that sits lower than the other.
Why one side of the door may sag
The two cables share the job of lifting, and they are meant to carry equal loads. If one cable frays and stretches, or if it slips on the drum, the load shifts. The side with the weaker cable drops a little, and the door twists slightly out of level.
You may notice the door looking crooked when it is partly open, or the gap under the door being uneven when it is closed. In some cases, the door tilts so much that a roller leaves the track. If that has happened, see garage door off track.
A sagging side can also show up as a door that jams partway, or one that moves with a jerk. The opener may strain unevenly. If you hear a sharp snap or see a cable go limp, the door may have lost support on that side entirely.
Do not attempt to level the door by hand. The remaining cable and the spring system are still loaded, and any shift could cause the door to drop or the weak cable to give way.
Why a loaded cable is dangerous to handle
A cable on a closed door is under a large amount of tension, because the springs are pulling it upward. If you touch a frayed section, broken wire ends can cut skin. If you move the cable or bracket, the stored energy can release in a way you cannot control. Cables have been known to whip, and brackets have pulled away from doors with force.
The bottom bracket in particular is a high risk part. It attaches to the door at a point that carries the full side load. Loosening a bracket bolt on a loaded door can cause the bracket to fly off and the door to jump.
This is why no do it yourself instruction for cable work belongs here. A technician will secure the door, relieve tension in a controlled way, and then inspect or replace the cable, drum and bracket as needed.
What you can do is observe, take photos, and keep the area clear. If you want a general sense of why professional help matters in this situation, see when to call a pro for garage door work.
Frayed, slipped or snapped: three different situations
A frayed cable is still in place but weakened. The door may work normally, with a little extra noise or a slight tilt. It is the earliest warning and the right time to have the cable looked at, since a planned repair is calmer than an emergency.
A slipped cable has come off its drum or out of its track position. The door usually sags on one side and may refuse to move. This often happens after the door has been run with a broken spring or when something has bumped the door. Our page about a cable slipped off the drum gives more detail.
A snapped cable is one that has broken completely. The door on that side loses its support, and the door may hang by a single cable, drop to the floor if open, or twist in the tracks. A snapped cable often goes together with a damaged roller, bent track or cracked panel.
All three need attention, but the urgency rises. If you can see broken strands, plan a call soon. If the door is crooked or not moving, stop using it and call right away.
Cable trouble and the rest of the system
Cables do not live alone. They connect to springs, drums, brackets, rollers and the door itself, so a problem in one place often shows up somewhere else. A frayed cable might be the first visible sign of a drum that has worn grooves, a shaft that has shifted, or a door that has been rubbing on one side.
The center bearing plate and end bearings hold the spring shaft in place. If a bearing plate cracks or a shaft end wobbles, the drum can tilt and the cable can wind unevenly. You can read about one version of that in cracked center bearing plate.
The bottom bracket is another partner. It is bolted into the door edge, and over time the bolts and the metal around them can loosen or crack. A bracket that pulls at an angle strains the cable end. If you see a bracket that looks bent or a gap between it and the door, mention it when you call.
Rollers and tracks matter too. A door that binds because of a worn roller makes the cable work harder and can let it go slack at the wrong moment. That is why a thorough visit looks at the whole path the door travels, not just the wire that has caught your eye.
Thinking of the cable as one link in a chain also helps you decide what to ask. A fair question is whether the drums and brackets were checked at the same time and what condition they were in.
What not to do
Do not run the opener on a door with a visibly frayed or slack cable. The opener adds force and motion, which can finish off a weakened cable. A fraying cable that breaks while the door is moving can drop a corner of the door suddenly.
Do not wrap tape, wire or rope around a damaged cable. It will not restore strength, and it can hide the wear a technician needs to see. Do not try to loosen or remove the cable from the drum or bracket for any reason.
Do not stand beneath a door with a damaged cable, and do not let children play near it. Keep vehicles out of the path if the door is open and cannot be closed safely.
If the door is closed, leave it closed. If it is open and stable, leave it open and secure the area. Neither position is without risk, which is why having the system inspected on site matters.
Describing the problem to the technician
Tell the technician where on the cable you saw the damage, such as near the bottom bracket or on the drum, and which side of the door it is on. Say whether the cable is frayed, loose, rusted or fully broken. If you can send photos, they help a great deal.
Mention how the door behaves. Does it tilt, jam, make noise or refuse to move? Did you hear a snap? Has the door recently been hit, or has the opener been struggling? These clues help point to other parts that may need attention.
Also say whether you have a torsion system with a bar above the door or an extension system with springs along the sides. If you are not sure, describe where the springs are. The cable arrangement differs between the two.
Once you call, the system is inspected on site, the options are discussed before any work begins, and the finished work and normal operation are reviewed with you. You do not have to guess at the repair in advance.
What the repair usually involves
After making the door safe, a technician looks at the cables, the drums, the bottom brackets and the springs together. A cable seldom wears alone. A worn drum groove can chew up a new cable, and a bracket that is bent or cracked can cause misalignment.
Replacing a cable generally means replacing it as part of a matched pair, since the two cables should wear and stretch at similar rates. Putting a fresh cable beside an old one can leave the door uneven. The technician will discuss this with you.
After the new cables are in place, the door is checked for level, balance and smooth travel. The opener limits and force are reviewed. Our overview of broken cable repair explains the service in more detail.
If the cable damage came from a spring failure, the spring side of the system is addressed too. See a broken garage door spring for that picture.
How to keep cables in good shape
The most useful habit is a regular visual check. Once a month, look at both lower brackets and the visible cable length from a safe position. A cable that looks the same as last month is a good sign. A new fray, rust patch or loose loop deserves attention. A short routine is laid out in our monthly visual inspection routine.
Keep water away from the bottom of the door when you can. A torn or missing bottom seal lets rain reach the lower hardware, so a tired seal is worth attention. Humidity and storm season in Houston make this a regular concern.
Avoid slamming or forcing the door, and keep the tracks clear. A door that rides smoothly puts less stress on the cables. Have the system looked at if you notice rubbing, noise or a change in how the door sits.
If you live in a community with rules about garage doors, ask your association whether a repair like this needs any notice. Requirements vary by city and community, and a simple question to the right office keeps surprises away. Also keep an eye out after any storm, since wind and debris can nudge a door and disturb a cable that looked fine the week before.
Finally, think about age. Cables, springs and rollers wear on a similar schedule. If one major part is being replaced, it is sensible to ask the technician about the others.
Questions and answers
How serious is a frayed garage door cable?
It is a real safety issue. The cable carries a large share of the door weight, and broken strands mean it is weaker than it looks. It may hold for a while or fail without warning. Stop using the door when you can, keep people clear and describe what you see when you call.
Can I tape or wrap a frayed cable until help arrives?
No. Tape or wire will not restore strength and can hide the damage a technician needs to see. The cable is under high tension whenever the door is closed. Leave it alone, avoid running the opener, and keep the area clear until the system has been inspected.
Why is one side of my garage door lower than the other?
A lower side often points to a stretched, slipped or weakened cable, though a broken spring or worn roller can also cause it. The two cables should share the load equally. Do not try to level the door by hand. Take photos and describe which side is low.
Do both cables need to be replaced if only one is frayed?
Often both are replaced together, because the two cables wear at similar rates and a new one next to an old one can leave the door uneven. The technician will inspect them and the drums, then explain the options before any work begins.
Is it safe to use the opener with a loose cable?
It is not. The opener adds force and motion that can finish off a weak cable or let it jump the drum. The door may then tilt or drop. Avoid the wall button and remote until the door has been checked, and tell the household not to use them.
Can humid Houston weather damage garage door cables?
Yes. Moisture can cause rust on the braided steel, which makes strands brittle and rough. Garages that take on water during heavy rain expose the lower cable end and bracket to repeated wetting. A monthly look at the cables helps catch early signs of corrosion.