Extension springs must match the weight and size of the garage door. This guide explains how to use door weight, spring length, and DASMA color codes to choose the right replacement.
What Extension Springs Do
Garage door extension springs stretch and contract to help lift the door. They are usually mounted along the horizontal tracks on both sides of the garage door.
The correct spring rating is important. A spring that is too weak may not lift the door properly, while a spring that is too strong can make the door hard to control and unsafe.
How to Choose the Right Extension Spring
Start With the Garage Door Weight
Extension springs are rated by the door weight they are designed to lift. The most reliable way to choose a replacement is to match the spring rating to the actual weight of the door.
If the old springs are original and the door worked correctly before failure, the existing spring color code can also help identify the replacement rating.
Measure the Spring Length
Measure the relaxed spring body length, not including hooks or end fittings. Extension springs should be measured when they are not stretched.
If the spring is damaged or stretched out from wear, compare both springs and check the product specifications before ordering.
Check the Spring Color Code
Many garage door extension springs use DASMA color coding to show the spring’s door-weight rating. The color is usually painted on the end of the spring.
Match the color code to the correct door weight range whenever possible.
Replace Springs as a Matching Pair
Extension springs usually work in pairs. If one spring breaks, the other spring has often gone through the same cycle life and may be close to failure too.
Replacing both springs helps keep the door balanced and avoids uneven lifting from one new spring and one worn spring.
DASMA Extension Spring Color Code Chart
The chart below shows common DASMA color codes and corresponding door-weight ratings for extension springs.
Do Not Ignore Safety Cables
Extension spring systems should use safety cables running through the springs. If a spring breaks, the safety cable helps contain the spring and reduce the risk of injury or property damage. Inspect the cables, pulleys, hooks, and track hardware before replacing the springs.
Quick Extension Spring Checklist
| What to Check | Why It Matters | What to Record |
|---|---|---|
| Door weight | The spring must match the weight it needs to lift. | Example: 120 lb door |
| Spring length | The replacement should match the correct relaxed spring length. | Measure spring body only |
| Color code | Helps identify the spring’s weight rating. | Example: Green = 120 lb |
| Quantity | Most systems use two extension springs. | Replace as a matching pair when appropriate |
| Hardware condition | Worn pulleys, cables, or hooks can cause problems even with new springs. | Inspect before installation |
Call Suplink Tech Corp Before You Order
If you are unsure about door weight, spring length, color code, or whether you need one spring or a pair, call us and we’ll help you review the details.
Call +1 386-359-9755 →