Although many homeowners use garage door openers, some simply open and close the garage door manually. Over time, the springs in the door can lose their tension and no longer lift the door fully. Adjusting the garage doors to keep them from drifting down requires adjusting the spring tension. Spring adjustment differs depending on the type of system you have. Torsion springs are on a bar directly above the garage door and require special winding bars that are available at garage door dealers. Extension springs ride along the side of the upper door tracks.
Close the garage door and engage the door lock. Clamp a pair of vise grips onto the right side track above the third roller with the handles of the vise grips pointing toward the center of the door opening. The vise grips act as a secondary door lock.
Set up a stepladder under the torsion spring winding cone. The winding cone is the end of the spring that is pointing toward the side. If you have two torsion springs, position the ladder under the right hand spring.
Clamp a second pair of vise grips around the torsion bar with the handle resting against the wall above the torsion bar. If you have a double spring system, you do not need to clamp vise grips on the torsion bar. The vise grips lock the bar to keep the cables tight on the two end drums on single spring doors. The second spring on a double spring system takes care of this.
Insert a winding bar into one of the holes on the winding cone facing you. Insert the winding bar fully and lift up slightly on the winding bar to get an idea of the pressure. Hold the end of the winding bar, and loosen the two set screws on the winding cone with a 3/8-inch wrench.
Allow the winding bar to slowly rest against the door. Grab the second winding bar. Lift the first winding bar, rotating the winding cone and spring until the next hole in the winding cone is visible. Insert the second winding bar into the hole in the winding cone, and pull the first one out of the winding cone.
Raise the second winding bar until it is horizontal and hold it there. Tighten the screws on the winding cone with the wrench. Slowly remove the winding bar from the winding cone. Remove the vise grips from the torsion shaft.
Remove the vise grips from the door track, and unlock the garage door. Lift the garage door open and stop it half way. The door should stay in the half-open position when you let go of it. Adjust the springs as necessary following the above procedure. If extra adjustments are necessary and you have a double spring system, adjust the opposite spring.
Open the garage door to the fully open position. Clamp vise grips on both door tracks directly under the bottom rollers with the handle pointing to the door opening.
Position your stepladder under the upper track on one side between the front of the garage and the front of the extension spring. The end of the extension spring cable has an S-hook that hooks into one of several holes on the upper track.
Grab the cable between the S-hook and the end of the spring with one hand, and pull toward the garage door. This provides slack on the end of the cable. Unhook the S-hook from the upper track and move it to the next hole towards the door. Slowly release your grip on the cable.
Move your stepladder to the other side of the door, and adjust the spring on that side the same way you did the previous spring. Remove the vise grips from the door tracks. The door should stay up.