Spring chart
Garage door torsion spring chart
Wire size is not something you can read off the spring. You work it out by measuring across the coils, and this is the chart that turns that measurement into a number a supplier recognises.
Wire size chart
Press the coils tight together, measure across 10 and across 20, and find the row. Twenty is the one to trust — an error over ten coils is twice as big by the time you divide.
| 10 coils | 20 coils | Wire size |
|---|---|---|
| 1.750" | 3 1/2" | 0.1770" |
| 1.875" | 3 3/4" | 0.1875" |
| 1.938" | 3 7/8" | 0.1920" |
| 2.000" | 4" | 0.2000" |
| 2.063" | 4 1/8" | 0.2070" |
| 2.188" | 4 3/8" | 0.2187" |
| 2.250" | 4 1/2" | 0.2253" |
| 2.344" | 4 11/16" | 0.2343" |
| 2.375" | 4 3/4" | 0.2375" |
| 2.438" | 4 7/8" | 0.2437" |
| 2.500" | 5" | 0.2500" |
| 2.625" | 5 1/4" | 0.2625" |
| 2.750" | 5 1/2" | 0.2730" |
| 2.813" | 5 5/8" | 0.2830" |
Residential range. Past 0.283" you are on a commercial door. Figures rounded to the nearest sixteenth, which is the precision a tape measure on a coiled spring actually has.
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Why not a caliper
Because the wire is bent into a coil, a caliper or micrometer sits on the curve and reads high. It is the most common reason a spring turns up and is wrong. Twenty coils and a tape beats a precision instrument here, which is not something you get to say often.
Inside diameter and wind
Two more numbers and the order is complete. Inside diameter is measured across the inside of the coil — on a house it is one of three: 1 3/4", 2", 2 1/4".
| Wind | Cone colour | Which side |
|---|---|---|
| Right wound | Red cone | Usually the right-hand side, looking out. |
| Left wound | Black cone | Usually the left-hand side, looking out. |
A double door carries two springs and they wind opposite ways. Check the second one rather than assuming it matches the first — a door that has been repaired before often has a mismatched pair.
Cycle life
| Grade | Cycles | At 4 openings a day |
|---|---|---|
| Standard | 10,000 | about 7 years |
| Long-life standard | 15,000 | about 10 years |
| High cycle | 25,000 | 14 to 20 years |
| High cycle, heavy | 50,000 | 20 years or more |
Never change your own springs
A torsion spring on a double garage door holds enough stored energy to break an arm, take out teeth, or worse. It is wound under tension with two steel bars, and if one slips it goes at the speed of the thing it was holding up. People are seriously injured doing this every year, and some are killed. There is no YouTube video that makes this safe, and the part costs less than the emergency room.
Exact price
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