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How To Measure Torsion Springs
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408 Fremont St.
West Chicago, IL 60185
(800) 383-9548
(630) 293-1312
Fax: (630) 293-1526
Home > Residential > How To Measure Torsion Springs |
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In order to process your order for springs, please provide the following information about each spring: (1) inside diameter, (2) wire size, (3) spring wind, (4) length, and (5) type of ends. Since an estimated 30% of manufacturers and service companies mix wire sizes it is critical that you measure both springs. Following the steps below will help in getting the correct dimensions.
If this information looks too technical, just call us, e-mail us or send a fax. Usually we can determine the springs you need from the size and make of door, but the spring dimensions help. The more information we have the better we can help you get what you need.  1. Determine the inside diameter. Measure to the nearest 1/16". Check this measurement against any corresponding numbers that may be on the spring plugs. For example, the more common plugs will have "175" for 1 3/4", "200" for 2", "258" or "263" for 2 5/8", etc. Confirm this dimension with the manufacturer of the door if there are any identifying marks on the door.
2. Determine the wire size. This is the thickness of the wire used to make the spring. Micrometers and calipers tend to be less accurate than measuring 20 coils with a ruler. Micrometers are not accurate because the only place to measure is usually the curved part of the spring where the wire will be several thousandths of an inch thicker. Calipers tend to be inaccurate because of errors converting from 64ths of an inch. Even digital calipers that our customers have used tend to be less accurate than 20 coil counts. We recommend using calipers and micrometers only to confirm your 20-coil measurements. To measure 20 coils insert the end of a tape measure between two coils or hook the tape on the end of the spring. Then, count 20 coils and pull the tape to the point where the 20th and 21st coils meet. Measure to the nearest 16th of an inch. Note that the hook on the end of the tape is slotted for measuring outside dimensions as well as inside dimensions. Since you are measuring the outside dimensions of the coils, you will need to pull the tape away from the end to get the maximum length. Pushing the tape into the end of the ruler will give you the minimum length, often 1/16" less. When measuring, make sure all the coils are compressed. If there are gaps between the coils, you will measure incorrectly and order the wrong spring.  If you have any doubt about your 20 coil measurement measure the total length of the spring and divide by the total number of coils. Use the 10-coil measurement to confirm your 20-coil measurement. Note: Wire sizes .200 and .237 are no longer used. If you have springs with these sizes contact us and we will calculate replacements for these. The specs generally fall between the wire sizes before and after them on the chart. The .289 was not included in our price list because of its low usage, but springs with that wire can still be made. Just contact us for prices. 
3. Determine the spring wind. This is the most confusing part of measuring springs so you will need to be careful. Examine the picture to the right.
Notice the spring on the left. When the end of the coil is on the bottom, it points to the left. This is a left wind spring. The end of the right wind spring points to the right. 
Another way is to look at the end of the coil when it is on top. If it starts winding clockwise from the 12 o'clock position to the right, it is a right wind spring. A left wound spring winds to the left from the 12 o'clock position.
A third way to determine the wind is to examine the spring where it is secured to the center spring anchor bracket. On most residential assemblies, if you can see the end of the spring wire at the bracket, the wire on both springs points down. If your springs are like these, the spring to the left of the bracket is right wind, and the spring to the right of the bracket is left wind. The opposite end of each spring, which is secured to the winding cone, points up when the end is facing you.  4. Measure the length of the spring. If the spring is unwound, simply measure the length. If the spring is broken, measure and add the two halves. Or, measure one half, and hold the position on the ruler, and start the measurement of the rest of the spring from that position. If the spring is wound, you will need to follow a different procedure. First, determine the number of turns the spring has on it. For each turn on the spring, the spring has grown one coil in length. Some springs are painted or marked with crayons to help the installer keep count of the number of turns. This is one way to determine the number of turns.  Another way is to calculate the number of turns. If your door has drums with 13" circumferences like the 400-8 you can usually determine the number of turns by dividing the height of the door in inches by the circumference of the drum in inches, and then adding one turn. A 7' high door with 13" drums typically has 7 1/2 turns and an 8' high door typically has 8 1/4 turns.  After you determine the number of turns, count off one coil for each turn and measure the remaining length of the spring to the other end. Here I am measuring the spring from the 8th coil. Exercise caution! Keep fingers out of the wound spring and away from the winding plug as if you knew the spring would suddenly unwind at any time, because it might.  5. Check the shape of the ends of the spring coil. Most springs have standard ends that are bent out slightly. If the spring you are ordering needs special ends, examine the chart and let us know which type of end it needs. Otherwise, you will receive a spring with standard ends. We also provide the springs with the cones already installed on them. Exceptions would be for Crawford and older BarCol springs. If you would like to order the springs without the cones, please let us know. Record this information and pass it on to us to use when processing your order. This will help eliminate any errors or delays in getting the right springs to you. |
| 408 Fremont St., West Chicago, IL 60185 · Ph: (800) 383-9548 / (630) 293-1312 · Fax: (630) 293-1526 · Send E-Mail |
