How To Measure Garage Door Springs. After you measure the length of this spring, you need to measure the diameter of the spring. Divide the height of the garage door by the cable drum circumference, then add one.
Divide the height of the garage door by the cable drum circumference, then add one. If the spring is broken or distorted, you can either measure both segments or simply count the total number of coils and multiply by the wire size (for example, 120 coils x.250 wire = 30 and 120 coils x.375 wire = 45). To properly measure a garage door torsion spring:
There are two ways to get the correct torsion springs for a garage door.
Step #1 measure the width and height (1 and 2) of your door opening in feet and inches to determine the garage door size you need. Spring length (how long each spring is) 4. There are two ways to get the correct torsion springs for a garage door. It is not uncommon to have two different size springs.