The springs on garage doors will brake or lose tension with time. Replacing these high-tension springs is a challenging and potentially dangerous project only fit for serious do-it-yourselfers. There are several types of garage doors, with their respective spring types and replacement techniques. For instance, your garage door may operate with extension springs, tension springs or a combination of both. Double garage doors with overhead springs use torsion springs mounted to a central bracket in the middle of the door and can be used as an example regarding the general principles for replacing garage door springs.
Close the garage door. Unplug the power cord to the garage door opener. If the opener is hardwired to the building's electrical system, remove the opener's fuse or disconnect the circuit breaker for the garage area. Disconnect the opener from the door. New models usually have a neutral position you can place the opener in while replacing the springs, while older models may require you to disconnect the opener altogether.
Ensure the replacement springs and the old springs are the same size. Measure the length and diameter of the old springs while in place, and compare with the new ones. Mark the location of the spring cone with a marker or chalk.
Unwind the old springs to release the tension on the garage door's bar. Insert a winding bar into one of the winding cone holes. Ensure the bar is at least 18 inches and the right diameter for your winding cone. Unscrew the spring's setscrew with a wrench. Pull down on the winding bar. Insert a second winding bar into another hole while still holding the other bar in place. Release the first bar, and pull down with the second bar. Repeat until the spring is unwound and there is no tension on the bar.
Remove the bolts that hold the stationary end of the spring to the anchor in the center of the door. Loosen the setscrews from the cable drums at the end of the garage door. Remove the drums, and slide the springs off the garage door bar.
Slide on the new spring. Ensure the side with the bigger hole, the stationary side, goes in first. Reassemble the cable drum. Repeat Steps 1 to 5 for the other spring. Insert the garage door bar into the cable drum. Tighten the garage door shaft by twisting the garage door bar.
Fix the stationary end of the torsion spring to the center of the door, and tighten the bolts. Make sure the stationary cone is flush with the anchor's bearing plate.
Wind the new spring onto the garage bar in the reverse way you unwound the old spring. Insert a winding bar and push up. Insert a second bar while holding the first bar in place, and then push up. Repeat until the spring is wound and reaches the mark you made in Step 1. It will generally take seven and a half turns to wind up a torsion spring. Repeat Steps 5 to 7 for the other spring.