Measuring a Garage Door Torsion Spring

Garage door torsion springs are made of Oil Tempered (ASTM A229) steel. The strength on a torsion spring is based on the dimensions of the spring. These dimensions are the spring length (overall length not including the cones / fittings), the inside diameter and the wire size. The active coils of the spring is the length of the spring multiplied by the wire size. The wire size is measured in decimal inches. Although it is possible to measure the wire size with a pair of calipers, we have found many individuals get erroneous results for the spring wire size with either a dial or digital caliper. For the average individual it is easier to count 40 coils of the torsion spring and measure that length to the nearest 1/8 of an inch. The decimal wire size is the length divided by the number of coils. The table below show the decimal wire size vs the length of 20 and 40 coils. Garage Door Co Repair Pros recommends using 40 coils to reduce the effect of measurement errors. Although there are "spring gauges" readily available which are based on 20 coils our service techs have been using the 40 coil method described above for many years with excellent success. The color shown in the table are the DASMA standard colors. If the wire is a common wire size it will be indicated with a 'YES' below. All spring measurements are to be performed when the spring is under NO tension.

The above description of measuring a garage door torsion spring is for reference purposes. Garage Door Co Repair Pros ALWAYS recommends that these springs be installed by a trained professional. If you are in the Chicago, IL area (our local service area) please use the contact links above for personal assistance in replacing your torsion springs.

Torsion Spring Wire Size Table, industry color, and length of 20 or 40 coils

Torsion spring standard inside diameters by manufacturer