All garage doors are operated by a spring system that attaches to the bottom of the door via a set of steel braided cables. These cables hold all the tension from the springs and help balance the door out. If you have a cable break the door will not work correctly if at all, and there is a good chance your door will go off track. However, when the cables break is not the only time to replace them. If your cables are frayed or kinked they should be replaced before they break.
Whether it is an extension spring or a torsion spring system the garage door is under tension and changing the cables can be dangerous and cause injury. If you do not have the proper tools, training and experience it is recommended that you call a professional and DO NOT attempt this repair on your own.
When buying your replacement cables the lengths matter. Most doors are 7ft tall but some are 8ft on a standard lift door your cable length should be the door height plus 17-18”.
7/16” universal short socket
Pair of Vice Grips
Flat Head Screwdriver
Step stool or Ladder
A couple extras that may be helpful:
Impact drill with a 7/16” magnetic bit on a 3-6” extension
Torsion Spring Systems:
These instructions are assuming your door is in the closed position and not jack knifed or off track. If one cable is snapped and the door is on the ground with one side off the ground slightly these instructions will work. When working on the door, work from right to left. Again, this can be dangerous and requires the proper tools.
Remove tension from springs:
Set your ladder or step stool in front and parallel to the door making sure that you will not be in front of the spring as you work on it. In order to remove the tension you must insert a winding bar into one of the holes on the winding cone of the spring. With a firm grip loosen each set screw using the 7/16” universal socket. When you do this the spring will no longer be attached to the torsion tube and will want to unwind, coming towards you. Bring the winding bar down slowly and rest against the door. You can either leave it this way and move onto the next spring and do the exact same thing, or use the other bar and unwind the spring completely, then go to the other side and unwind it too.
Loosen both drums. You will do this using the 7/16” universal socket on the set screws again. Do not completely remove the set screws, just loosen them enough the drums will spin freely. Once you have done so you can remove the cable from the slot on the drum.
Remove the cables from the bottom fixtures of the door. Use the flat head screwdriver to pry the cable off of the peg on the bottom fixture. If you’re having a hard time getting it off you may need to loosen the jamb bracket from the wall and pull the track away from the door to get more space.
Replace your old cables with the new ones, by first reattaching them to the bottom bracket. When you run your cables up to the drums, keep them between the door and the jamb brackets and the door and behind the rollers.
Set your drums and cables. Remember work left to right.
If you left your winding bars resting on the door you will insert the cable in the drum and wrap it tight then tighten down the set screws. Once the set screws are tightened down on the first drum, set your vice grips on the torsion tube and set them against the wall this will keep the cable from coming loose off of the drum.
If you unwound the springs completely then tighten the set screws on the drum first with the slot for the cable facing the front. Wrap your cable while turning the drum and torsion tube at the same time, then put your vice grips to the wall.
Go to the other side and wrap the cable around the drum on the right side by spinning it and then tighten the set screws.
Tighten springs. If you have your winding bars resting on the door just lift it up so it is parallel to the floor then tighten your set screws back down. Do the second spring the same way. If the you unwound the springs, wind them up one at a time.