How to Replace a Broken Cable
Before you begin replacing a garage door cable on your garage door, make sure you have the necessary tools. It is not possible to predict all repair circumstances.
The following steps must be followed in order to prevent any damage to a door and a person. We highly recommend hiring a professional technician to do this job and do not take any responsibility for any outcome of someone implementing the following steps.
Take it Apart
The garage door size determines the cable size. For the most common residential 7 feet tall door, you will need an 8’6” cable. Sizes of tools used for cable replacement may vary in size, too, so have a combination of sizes available.
You will need locking pliers or a vice grip, a set of cables, wrenches, winding bars, sockets, stepping ladder, ratchet, safety glasses, and gloves. A proper outfit (e.g. gloves, work boots, and safety glasses) is needed, too.
Be cautious of pointed edges on cables to avoid injury.
To begin with, unplug and disengage the garage door opener by pulling on the emergency release cord. There should be a red rope with a handle that is positioned on the top rail (depending on your opener). Doing so will allow you to manually open and close the garage door.
Close the door and make sure it touches the ground evenly. Walk toward the center of the garage door and slacken the set screws on the springs with 1/4 turns. Don’t forget to fully insert the winding bars as well as use both bars at the same time to prevent injury. Do not get in the bars way!
Unwind the spring until all of the tension has been removed. If the door has two springs, do the same with the second spring.
After springs’ tension is removed, take a wrench and slacken the set screws on the cable’s drum at the top left corner of the garage door. Then, remove the cable from its drum. By the bottom of the door, release the cable where it connects to the bottom bracket.
Installing the Cable
Install the new cable onto the bottom bracket. Then, thread the cable up toward the cable’s drum. Make sure the cable is running behind the rollers (between the tracks and rollers). Do this for each side of the door.
Insert the cable into the slots of the drum. Validate that the cable is set properly and is not overlapping. Wind the cable onto the drum, and then slide the drum over toward the bearing plate. Then, turn the drum counterclockwise (right drum-clockwise) until the cable sits tight. Now, tighten the set screws, but do not overdo so.
While holding the cable, use your vice grip pliers on the metal shaft that goes across the entire door (along the wall) to hold it tightly in place. Then, go to the other side of the door and follow the same instructions. After completion, increase the springs’ tension using your winding bars. Remember to only increase the tension at a ¼ turn at a time.
Remove the locking pliers from the metal shaft and check that the garage door is balanced (i.e. stays at the same place where you leave it). Before plugging the opener back in, make sure to manually lift the door all the way up, while checking that there is an even tension between the drums and cables. In case there is no tension on one side, repeat the process again, until you get an equal tension. Engage the door by pulling the emergency release, and then plug the opener back in. Again, make sure there is tension between the drums and cables while the door is fully open.