There are two kinds of garage door springs -- torsion springs and extension springs. Torsion springs are the kind wound-up on a rod above the garage door opening. There are a pair of them--one on each side of the center of the door. When one breaks the other often follows, so save the cost of another service call, and have both replaced when one breaks. People have been maimed and some killed tightening or releasing these metal springs. Hire a professional.
Torsion springs have four primary characteristics: 1. Length, 2. Inside diameter 3. Wire size, and 4. Wind. These dimensions determine the torque - how much weight the spring will lift, and cycle life - how many times the door will open and close before the spring breaks.
In one end of the spring is the stationary cone, which is usually attached to a spring anchor bracket. In the other end is the winding cone, which is wound with winding bars. This cone is secured to a hollow shaft, usually 1" in diameter. Many garage door springs are color-coded, but there is no real consistency among manufacturers and distributors. Winding cones are often painted to designate wind - red for right wind and black for left wind. Secured to each end of the shaft is a cable drum, and hooked into the cable drum is the top end of the cable.
Garage doors rise from the vertical tracks up into the horizontal tracks. As the door rises the torsion springs unwind and the weight of the door is transferred to the horizontal tracks. When the door is fully open only about one turn remains on the springs.
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The other kind of springs -- the kind that run along the upper, right and left door tracks, and extend/stretch to do their job, called extension springs -- are not as difficult a home repair. However, some safety measures are in order. Remember, when these springs are extended (door down) they are stretched to potentially deadly force--they may be lifting a 400 pound door. Extension springs are also used for trampoline springs.
Garage door extension springs have four characteristics: length, inside diameter, wire size and type of end. There are three types of ends: double loop and open loop for doors weighing up to 200 pounds, and clipped ends for doors weighing over 200 pounds. Most residential springs are manufactured in 10-pound lift increments. Though extension springs have these four characteristics, manufacturers generally do not make springs by the dimensions you may find on your door. Every manufacturer has its own design for making metal springs. Because of this, when ordering extension springs you will need to provide the following information:
Extension Springs tend to stretch over time so you will need to compress the coils when measuring the length. You may need to insert a shaft in the middle of the spring to keep it straight while compressing the coils. Some springs are ruptured so badly you may need to measure and count coils to calculate the length. |
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Replacing extension springs on older garage doors with longer or shorter springs may require additional work.
If your older springs are longer than the new springs, you will need to adjust your cables so there is 2" of additional length for every inch that your new spring is shorter than the old springs. If your cables are not adjustable, you will either need to replace the cables or order longer springs. Custom extension springs cost 50% more than the standard springs.