One of the final steps in installing a garage door is adding tension to the garage door spring. The torsion springs on a garage door wind around the torsion shaft, providing the tension necessary for the spring to rotate the torsion and lift the weight of the garage door. Windings bars, which are necessary to add tension to garage door springs, are round steel bars that are 450 mm (18 inches) long and are available at garage door dealers. Measure the height of the garage door, as you will need that information when winding the torsion spring.
Position a stepladder on the left side of the door under the drum. The drum is the round wheel that the end of the door cable wraps around. Ensure that the loop end of the cable is around the pin on the bottom door bracket. Feed the cable behind the rollers all the way up the door. Bring the end of the cable between the wall and the cable drum.
Locate the notch on the side of the drum pointing to the wall. Insert the end of the cable into the notch, with the button on the end of the cable hooking under the notch lip. Rotate the drum forward with one hand, while guiding the cable over the first set of grooves on the outside circumference of the drum. Push the drum against the track bracket, and hold the drum to keep the cable tight. Tighten the set screws on the drum with a 9 mm (3/8 inch) wrench.
Lock a pair of vice grips over the torsion shaft between the drum and the end of the spring. The handles of the vice grips should rest on the back wall above the torsion shaft. Let go of the cable drum when the shaft is locked in the vice grips. Move the ladder to the right side of the garage door under the right drum. Feed the cable behind the rollers and in between the cable drum and wall.
Insert the cable into the notch on the drum and rotate the drum forward to wrap the cable onto the drum. Push the drum against the track bracket and rotate the drum forward to keep tension on the cable. Hold the drum with one hand, and tighten the set screws with the 9 mm (3/8 inch) wrench.
Place the stepladder under the winding cone of the torsion spring. The winding cone is the end of the spring pointing to the cable drum, and has four equally spaced holes on the outside circumference. Insert a winding bar firmly into one of the holes until you feel the end of the winding bar seat in the bottom of the hole. Wrap a piece of masking tape around the winding bar just above the winding cone. Pull the winding bar out and insert the second winding bar into the winding cone and wrap tape around the winding bar. The tape will serve as a guide to let you know if the bar is seated fully in the cone while winding.
Spray a horizontal line across the length of the spring from one end to the other with a can of spray paint. Alternatively, use a yellow grease marker to mark a line down the length of the spring. As you wind the spring, the horizontal line will turn into several vertical lines. A wound spring will have the same number of vertical lines as the door height. For example, a 210 cm (7 foot) high door should have seven vertical lines on the spring.
Lock a pair of vice grips on the front edge of the door track just above one of the rollers on the door. The handles of the vice grip should be pointing toward the centre of the door. This will keep the door from raising up as you add tension to the spring.
Insert a winding bar into the hole on the winding cone facing you. Lift up on the end of the winding bar until the next hole on the winding cone is facing you. Insert the second winding bar fully into the hole, and pull out the first winding bar. Raise the second end of the second bar until the next hole is facing you. Insert the winding bar into the hole, and remove the upper winding bar.
Continue the winding of the spring until you have the correct number of vertical lines across the spring. You will feel the tension pressure on the spring as you are winding. Once the correct number of lines are on the spring, allow the last winding bar to rest inside the cone and against the top section of the door. Tighten the set screws on the winding cone with the 9 mm (3/8 inch) wrench.
Place a winding bar into the hole above the winding bar that is still in the spring. Gently pull up until you can remove the lower winding bar. Pull out the lower winding bar and gently let go of the upper winding bar. Pull the upper winding bar out of the spring. Repeat the winding process for the opposite spring if you have a two-spring door.
Remove the vice grips from the torsion shaft on the left side of the door. Remove the vice grips from the door track. The garage door spring now has tension to lift the garage door.
Doors that use stretch springs on the upper tracks do not get tension added to the spring. The springs on these types of doors attach when the door is in the open position. The door adds the tension to the these springs. If you have stretch springs, refer to your installation manual.
Winding bars are the only tool to be used to wind springs. Attempting to use any other tool to wind the spring can cause serious injury. If you are the least bit uncomfortable performing this task, call a door professional to add the spring tension. You are adding enough tension to a spring to lift a door that weighs over 115kg.