Making Measurements

There are three important pieces of information that you will need to get in order to select the proper springs for your garage door. These are the door height, the spring length without the loops, and the door weight. If you can identify the manufacturer and model number you may not need to weigh the door. Just click the "Find by Model Number" tab below.

One method for weighing a 16' or wider door is to slide your scale under the end of the door on the side that has a broken spring. Raise the other side to the same height and then support it to keep the door level.

The door weight can be difficult to calculate. You must use an analog scale, as most digital scales do not respond to changes in the door weight caused by the door binding in the tracks. If you have two broken extension springs, slide an analog scale under the center of the door to get the total weight. If one of your two extension springs is broken, you can slide the scale under the door under the side with the broken spring as pictured to get half the weight.

Shake the door and check each of the rollers for binding. If one spring is broken, the weight you read off the scale at the broken will be 1/2 the door weight. If you have a total of two springs on your door, and if both springs are broken, the scale will read the total door weight. For more information, see the first five steps of our Extension Spring Replacement tutorial.

If you have a total of four springs on your door with two springs on each side of your door, open the door, remove the second spring on the side with the broken spring, and lower the door onto the scale on the side that had the broken spring. With both springs off on this side, you can double this weight to determine your total door weight. It is important to note, however, that since you can't weigh the door at the very end, you will need to adjust your weight to factor in the distance from the end. For example, if the center of your scale is 12" from the very end, you will need to add to the weight your scale shows. A percentage determined by dividing 16' by 15' arrives at 106.66% percent. Hence a weight of 100 pounds X 106.66% = 107 pounds. Double this, and the total estimated door weight should be around 214 pounds. This door would use two 210 pound lift extension springs. Or, if the door has four extension springs, the door would use two 100 pound lift springs and two 110 pound lift springs.

A more accurate method for weighing either a torsion spring door or an extension spring door is on our YouTube channel.

The door height also helps to determine which springs you need. For example, the extension springs made for 14' high doors are intended to stretch twice as far as the springs made for 7' high doors. As a result, the un-stretched length of an extension spring generally increases as the door height increases.

Another measurement you will need to make is the un-stretched spring length, not including the ends. Extension springs tend to stretch over time, so you will need to remove the spring from the door and 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.

While the door industry has standardized on spring lengths, there are multiple spring lengths for some of the more common door heights.

If you decide to purchase an extension spring with a shorter un-stretched length than your old spring, you will need to adjust your cables. There will need to be 2" of additional length for every inch that your new spring is shorter than the old spring. If your cables are not adjustable or are too short, you will either need to replace the cables or order a longer spring. If you need a spring with dimensions not listed in our parts catalog, we can order a custom spring. These generally cost about 50% more than our standard springs, so it is probably better to change the cables instead.

If your new spring is longer than your old spring, you will need to adjust the cables to shorten the pull. Sometimes this requires mounting the S-hook on the new springs closer to the garage door.

It is also helpful to examine your spring for color codes. The lifts for extension springs follow these colors:

• Tan - 100#, 200# & 300#
• White - 110#, 210# & 310#
• Green - 120#, 220# & 320#
• Yellow - 130#, 230# & 330#
• Blue - 40#, 140# & 240#
• Red - 50#, 150# & 250#
• Brown - 60#, 160# & 260#
• Orange - 70#, 170# & 270#
• Gold - 80#, 180# & 280#
• Light Blue - 90#, 190# & 290#.

This pattern is repeated through all the lifts.

Types of Extension Spring Ends

From front to back: Open ends, double-loop ends, and clipped ends. There are three types of ends on extension springs, and each of the springs has its own advantages and disadvantages.

Open looped ends are the easiest to replace. You will not need to open the eye-bolt, and you will not need to disassemble the pulley. One disadvantage, though, is that the whole spring relies on an open wire at the end. If this is the only part of your spring that breaks, you may be able to save a few dollars and sometimes if you put a clip on the end of the spring as we show above.

Double looped ends are more sturdy than open loops, as there are two coils of the spring that connect to the eye-bolt and the pulley. One disadvantage, though, is that they take longer to replace.

Clipped ends are even more durable than double loops. The spring clips put less stress on the spring ends to help lengthen the life of the spring, these come standard on extension springs for doors that weigh 200 pounds or more. The disadvantage, though, is that they can be more difficult to replace.