Tension is applied through torsion springs to the cables, which roll onto circular spools called drums. If you have every looked at your garage door and noticed cables not under tension you may have garage door cables off drums. Why do garage door cables come off drums? Most of the time cables slip due to natural causes like wear while other times it is the result of improper garage door operation or maintenance. Garage door cables are under an extreme amount of tension. Never attempt to fix cables that have come off the drums unless you are a certified repair technician. Here are a few possible reasons why your cables may have slipped off the drums.
Broken Torsion Spring
On single car garage doors with only one torsion spring, a broken spring removes tension on the cables. This will usually cause the door to slam to the ground unwinding the cables in the process. Since torsion springs break at around 10,000 cycles, this is one of the most frequent causes of cables coming of the drums. Always try to have two torsion springs installed on every garage door. If one spring breaks, the other spring can support the door until it can be repaired. This eliminates the possibility of the door being damaged from violently slamming to the ground.
Door Set On Object
The most common user error reason for cables to slip off the drums is setting your garage door down on something. Often times the bumper of a vehicle or chair may stick out over the garage door opening without triggering the photo eye safety reverse feature. When this happens the weight of the door is unevenly distributed, leaving slack in the cables on one side of the door. Always make sure all objects are clear of the door opening before attempting to close your overhead garage door.
Improper Spring Tension
Installing the incorrect torsion spring (length, wire size and inside diameter) on your door can also cause the cables to slip off the drums. If the springs are too powerful based on door size and weight the cables will slack and pop off the drums. If they aren’t strong enough the door will be strong off the bottom and weak at the top causing the cables to unravel when the door is open. Back-wound springs will also cause the cables to slip. Applying tension to the springs in the wrong direction during installation will throw the cables also.
Rusted and frayed cables are prone to breaking in half over the long term. Always make sure you use the correct diameter of cable for the weight of the door you plan to install. Residential doors work just fine with 1/8″ diameter cable, but heavier doors over 500 lbs may require 5/32″ or 3/16″ cable. Inspect cables annually, replacing any that appear frayed or rusted. Make sure cables do not rub against other objects during operation and always make sure they are sized correctly.
Wrong Size Drums
Installing the incorrect drums causes slack in the cables, which will also cause them to slip off the drums. Drums are sized based on door height and the type of track lift. Standard lift track requires drums calibrated and sized for 8ft, 12ft ,18ft and 32ft tall doors. Special drums for high-lift and full vertical lift applications are needed. They are shaped and sized to keep constant tension on the cables. Improper drum installation and incorrect drum size will throw the cables.
In situations where you have troubleshot all possible problems you may need the help of accessories to keep cable tension. Cable keepers and pushers can be used to assist in keeping the proper amount of tension on the cables. Cable keepers are a small clip that prevents slack in the cables near the bottom of the garage door. Pusher springs are available in 18″ and 27″ sizes and are installed at the top of the door at the end of the horizontal tracks. They push against the top section of the door when it is overhead. These devices are especially useful when using side mount jackshaft openers.
- Pusher Springs (18″ & 27″)
- Cable Keepers
Cables Off Drums Troubleshooting Checklist
- Wrong Springs
- Incorrect Drums
- Door Set on Object
- Check Spring Tension
- Cables Worn Out
- Incorrect Installation
- Install Keepers & Pushers
This article covers the most common reasons for cables being thrown off the drums – not every possible reason. If you cannot remedy the situation with this checklist consult your local garage door professional. You may have a more serious problem like track alignment , incorrect material or incorrect installation.