How to Identify the Correct Garage Door Torsion Spring
Choosing the correct garage door torsion spring requires more than finding a spring that looks like the one being replaced.
Two torsion springs can look nearly identical while having very different operating characteristics. Small differences in wire size, inside diameter and spring length can significantly change the torque a spring produces and how many cycles it is designed to provide.
When replacing an existing torsion spring, the markings and measurements of the original spring provide important information. But the ultimate goal is not simply to duplicate its appearance — it is to make sure the spring is properly matched to the garage door and spring system.
This guide explains the information used to identify a torsion spring and what to consider before ordering a replacement.
The Four Basic Torsion Spring Measurements
When identifying an existing torsion spring, start by collecting four basic pieces of information:
- Wire diameter
- Inside diameter
- Spring length
- Wind direction
These measurements describe the physical spring and are an excellent starting point when identifying a replacement.
We have a separate illustrated guide showing exactly how to obtain each measurement.
1. Determine the Spring Wire Diameter
Wire diameter — often referred to as wire size — is one of the most important specifications of a torsion spring.
Even a small difference in wire diameter can substantially change the characteristics of the spring.
Because individual coils can be difficult to measure accurately with ordinary tools, wire size is often determined by measuring the combined length of multiple coils and comparing that measurement with a wire-size chart.
For example, measuring across 10 or 20 coils reduces the effect of small measurement errors.
2. Determine the Inside Diameter
The inside diameter, or ID, is the diameter of the opening inside the spring coil.
Common residential torsion spring inside diameters include sizes such as:
1¾”, 2″, and 2⅝”
Other sizes are used depending on the application.
The inside diameter is often marked on the spring’s winding or stationary cone. If the marking is missing or unreadable, the spring can be measured directly.
The inside diameter is an important part of identifying the spring and must not be confused with the spring’s outside diameter.
3. Measure the Spring Length
Torsion spring length is measured across the spring coils only, excluding the winding and stationary cones.
For an unwound spring, measure from the first coil to the last coil.
Spring length matters because it works together with wire size and inside diameter to determine the spring’s operating characteristics and expected cycle life.
A spring that has broken into two pieces can still be measured. Measure both coil sections and add the measurements together to determine the original coil length.
4. Determine the Wind Direction
Torsion springs are manufactured as either:
Left-wound (LW)
or
Right-wound (RW)
Wind direction is critical. A left-wound spring and right-wound spring are not interchangeable simply because their other dimensions match.
On many standard torsion systems, the spring’s position on the shaft can help identify its wind direction — but don’t rely solely on which side of the garage the spring happens to be located.
Identify the actual direction of the spring coils.
G.A.S. Hardware also uses red and black winding cones to help distinguish spring configurations, but cone color should not replace properly identifying the spring’s wind direction.
Is the Color on a Garage Door Spring Enough to Identify It?
No.
Color markings can be useful identification aids, but they should not be the sole method used to select a replacement torsion spring.
Paint markings, cone colors and other visual identifiers can vary by manufacturer or system.
A replacement spring should be selected using its actual specifications and the requirements of the garage door — not simply because:
“The old spring had a red mark, so I need another red spring.”
Measure and identify the spring.
Single-Spring vs. Two-Spring Garage Door Systems
Garage doors can use one torsion spring, two torsion springs or, in some applications, multiple springs.
On a typical two-spring residential system, the springs work together to counterbalance the weight of the garage door.
If one spring in a matched pair breaks, it’s important to identify both springs and the overall door configuration, rather than treating the failed spring as an isolated component.
This is especially important if:
- The springs are different sizes
- One spring has previously been replaced
- The history of the system is unknown
- The door doesn’t balance correctly
- The existing springs may not be original
Simply duplicating a spring that was already incorrect won’t correct the underlying problem.
What If the Existing Torsion Spring Is the Wrong Size?
Sometimes the spring you’re replacing isn’t the correct spring for the door.
Perhaps a previous repair used an available spring rather than the properly calculated spring. Maybe the garage door was modified. Perhaps insulation, reinforcement or hardware changed the door’s weight.
In those situations, accurately measuring the old spring only tells you:
what is currently installed.
It doesn’t necessarily tell you:
what should be installed.
When there is reason to question the existing spring configuration, spring selection should be based on the requirements of the garage door rather than blindly duplicating the old spring.
Why Garage Door Weight Matters
The purpose of the torsion spring system is to counterbalance the weight of the garage door.
That means spring selection ultimately has to produce the appropriate torque for the door.
Door weight can vary considerably depending on:
- Door dimensions
- Door material
- Insulation
- Windows
- Reinforcement
- Decorative hardware
- Previous modifications
This is why identifying a spring by appearance alone is unreliable.
The spring system and the door must work together.
What Do Cable Drums Have to Do With Spring Selection?
The cable drums are another part of the counterbalance system.
As the torsion shaft rotates, the drums wind or unwind the lift cables that raise and lower the garage door.
Different drum configurations can affect the relationship between spring torque and door movement.
For a straightforward replacement on an unchanged system, accurately identifying the existing spring may provide much of the information needed.
For unusual doors, modified systems or applications where the existing springs are questionable, door weight, drum configuration and other system specifications may also need to be considered.
This is particularly important with commercial and specialty garage doors.
Does Spring Cycle Life Affect Which Spring I Should Choose?
Yes — but only after the spring has been properly matched to the door.
Different spring configurations can sometimes provide the required torque while offering different expected cycle lives.
For a frequently operated door, a higher-cycle spring configuration may be desirable.
For example, G.A.S. Hardware offers torsion spring configurations with cycle ratings of up to 70,000 cycles for appropriate applications.
But don’t make this mistake:
Higher cycle rating ≠ correct spring.
Correct spring performance comes first. Desired cycle life comes second.
Can I Replace a Torsion Spring With One That's "Close Enough"?
A garage door torsion spring should not be selected simply because its dimensions are close to the original spring.
Changes in wire size, inside diameter and spring length affect spring performance.
A spring that physically fits the shaft may still produce the wrong torque for the door.
An improperly matched spring can result in a door that:
- Feels unusually heavy
- Rises on its own
- Won’t remain in a partially open position
- Operates unevenly
- Places unnecessary strain on the garage door opener
- Places additional stress on other components
The objective is a properly counterbalanced garage door, not merely installing a spring that fits.
A Garage Door Professional has access to information and calculators that will provide correct-replacement springs if the original size is not available. NEVER attempt to use a spring that seems “close enough” – it is very dangerous and can cause serious property damage and injury.
What If My Torsion Spring Is Broken?
A broken torsion spring can still provide most of the measurements needed for identification.
Wire diameter and inside diameter can generally still be determined normally.
For spring length, measure the coil section on both sides of the break and add them together.
Do not include the gap created when the spring broke.
And remember that a broken spring is normally in an unwound condition, which is what we want when determining its relaxed coil length.
Frequently Asked Questions
How do I know what size torsion spring I need?
Start by identifying the existing spring’s wire diameter, inside diameter, length and wind direction. If the existing spring configuration is known to be correct and the door hasn’t changed, those measurements provide important replacement information. If the existing setup is questionable, the garage door’s specifications may also need to be considered.
Can I identify a torsion spring by its color?
Color can provide useful information in some systems, but it should not be used as the sole method of identifying a replacement spring.
Can I measure a broken torsion spring?
Yes. Wire diameter and inside diameter can still be measured, and the lengths of the broken coil sections can be added together to determine the spring’s original coil length.
Do I need to know the weight of my garage door?
Not necessarily for every straightforward like-for-like replacement. Door weight becomes particularly important when the existing spring configuration is unknown, questionable, modified or needs to be recalculated.
Are left-wound and right-wound torsion springs interchangeable?
No. Wind direction is an important spring specification and must be correctly identified.
Should I replace both torsion springs if only one breaks?
If two springs were installed together, they have generally experienced similar numbers of cycles. The age, condition and specifications of both springs should be considered when determining the appropriate repair.
Correct Identification Starts With Accurate Measurements
Selecting the correct torsion spring starts with knowing exactly what you’re working with.
Accurate measurements help identify the existing spring, while understanding the garage door and counterbalance system helps determine whether that spring is actually appropriate for the application.
G.A.S. Hardware supplies professional-grade residential and commercial torsion springs in a wide range of sizes and cycle-life configurations.
