Garage door cables with frays or broken pieces require replacement. When replacing a torsion spring garage door cable, it is advisable to replace both cables at the same time. Torsion springs require a pair of 18-inch winding bars to unwind and wind the spring. Winding bars and garage door cable are available at garage door dealers and some home improvement centres. Measure the height of your garage door so that the service department can obtain the correct length cables for your door. Garage door cables have a loop on one end and a button on the opposite end.
Position a stepladder under the winding cone end of the torsion spring pointing to the side of the door. The winding cone is the portion with four evenly spaced holes around the sides, and has two small square set screws. Insert one winding bar into the hole on the winding cone facing you. Insert the bar all the way until you feel it seat inside. Wrap a piece of electrical tape around the bar just above the cone. This will help you clearly identify whether the bar is fully inside the cone while unwinding. Do the same thing with the second winding bar.
Insert a winding bar into the nearest hole facing you on the winding cone. Lift up on the opposite end of the winding bar slightly to get a feel of the tension you will be receiving. Hold the winding bar firmly in one hand, and loosen the two set screws on the winding cone with a 3/8-inch wrench. Each set screw will be loose after two turns counterclockwise. Slowly lower the end of the winding bar against the top of the door.
Position the second winding bar into the hole facing you on the winding cone. Lift up on the opposite end of the winding bar until you can pull the first winding bar out of the winding cone. Slowly lower the second winding bar until it rests against the top of the door. Repeat the process of unwinding using one bar to hold the tension and releasing the previous bar until the spring is fully unwound. If you have two springs, repeat the process for the opposite spring.
Reposition the stepladder under the drums that the cables wrap around on the end of the torsion shaft. Loosen the set screws on each drum until the drum turns freely on the shaft.
Unhook the end of the garage door cable from the inside of each drum. Pry the end of the cable loop around the pin on each bottom bracket of the garage door with a flathead screwdriver. Pull the cable away from the garage door on each side.
Press the loop end of the garage door cable around each pin on the bottom brackets. Thread the length of the cable behind each roller stem and the wall. Lay the end of the cable over the top rollers on each side.
Place the stepladder under the left-side cable drum. Grab the end of the cable, and thread it behind the drum and the wall. Place the button on the end of the cable inside the groove on the inside of the cable drum. Rotate the drum forward to roll the cable over the drum. The cable will thread into grooves on the drum. Hold the drum forward with one hand, and tighten the two set screws with the wrench. Continue holding the drum, and lock a pair of vice grips around the torsion shaft with the handles of the vice grips resting on the wall above the shaft.
Move the stepladder over to the right-side cable drum. Attach the cable to the right-side drum as you did the previous drum. Roll the drum forward with one hand and hold the drum. Tighten the set screws on the drum.
Lock a pair of vice grips on the vertical track above a roller. The handle of the vice grips should point to the garage door. This will help prevent the door from accidentally raising while you add spring tension.
Place the stepladder under the winding cone of the torsion spring. Make a line across the length of the spring from each end with a can of spray paint or a grease marker. As you wind the spring, this single horizontal line will become several vertical lines. The rule of thumb is one horizontal line for each foot of door height. For instance, if you have a seven-foot-high door, wind the spring until you have seven vertical lines.
Insert a winding bar into the hole facing you on the winding cone. Lift up on the end of the winding bar until you can insert the second winding bar into the hole below the first. Insert the second winding bar firmly, and remove the first winding bar. Raise the second winding bar until you can insert the other winding bar into the next hole on the winding spring. Continue this winding process until you have the appropriate number of vertical lines. Allow a winding bar to remain inside the winding cone and resting against the top section of the door, when you have the spring wound. Tighten the set screws on the spring with a wrench.
Insert a winding bar into a hole above the first winding bar. Lift up on the winding bar just enough to remove the first bar. Slowly release the second winding bar and pull it out of the winding cone. Repeat the winding process on the opposite spring, if your door uses two springs. Remove the vice grips from the torsion shaft and the garage door track.
Torsion springs are under extreme pressure. They raise the weight of your garage door. If you are not completely comfortable performing this task, call a garage door service professional.