Garage Door Extension Springs
Garage door extension springs are installed along the horizontal track. Unlike torsion springs, extension or stretch springs fasten to a cable pulley system. As the garage door lowers the springs stretch out half of the door height. When the door is closed the springs are under full tension, helping to raise the door on the way up. These springs are typically used by the do-it-yourself homeowner since they are safer to install than standard torsion springs. They are also used in low headroom situations where there is not enough space for torsion springs to fit.
Since extension springs have to stretch during the loading phase and contract to help the door raise, length plays a major role in door operation. Extension springs for a 7ft tall garage door are a standard 25 inches and stretch 42 inches. Springs for an 8ft tall door are usually 28 inches and stretch 48 inches.
Extension Springs for 7 ft Tall Garage Doors (25-42)
|Color||Weight||Cycles/ Loop||Length/ Weight|
|TAN||100 lb||25,000 Double Loop||25-42-100|
|WHITE||110 lb||25,000 Double Loop||25-42-110|
|GREEN||120 lb||25,000 Double Loop||25-42-120|
|YELLOW||130 lb||25,000 Double Loop||25-42-130|
|BLUE||140 lb||25,000 Double Loop||25-42-140|
|RED||150 lb||25,000 Double Loop||25-42-150|
Extension Springs for 8 ft Tall Garage Doors (28-48)
Inside diameter is a measurement of the width of the hollow space inside the spring. Most extension springs have small inside diameters of less than 2 inches. Inside diameter is more important when using torsion springs as opposed to extension springs. Springs with a larger inside diameter (ID) are used on heavier doors.
If all of the labeling is worn or rusted off your extension spring you will have to use your best judgement when matching springs. Examine the thickness of the springs by doing a 20 coil count. That means lay a tape measure over the spring and count 20 individual coils. Do so on the spring you intend to purchase as well, making sure your length of 20 coils is identical on each spring.
The end loops of extension springs are made in three specific models. The three types of end loops are designed to support specific door weights. Light weight garage doors require single open loop ends, while heavier doors require double loop ends or clipped ends.
- Singe Open Loop – Light Weight
- Double Closed Loop – Mid Weight
- Clipped End – Heaviest Weight
Finding Door Weight
If you aren’t able to match springs or have lost existing springs you will need to get a dead door weight measurement. To do this make sure all tension is off any springs connected to your garage door system. Use a standard bathroom scale to weigh your garage door. Use 3 pieces of wood on top of the scale if you are concerned about breaking it. Add about 5 lbs to the measurement you get and match your door weight to extension spring pull weight.
Replace Extension Springs in Pairs
Always replace extension springs in pairs. Not only will this save you time, but it will also save you money. Extension springs are rated for an estimated 20,000 cycles. If your springs were installed at the same time chances are the intact spring will break soon as well. Not replacing both could result in your garage door “stair stepping” when in motion. This means the new spring is stronger than the older spring and pulls harder on one side. Replace all the extension springs on your garage door for smooth and quiet operation.