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.

Length

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)

Color	Weight	Cycles/ Loop	Length/ Weight
TAN	100 lb	25,000 Double Loop	27-48-100
WHITE	110 lb	25,000 Double Loop	27-48-110
GREEN	120 lb	25,000 Double Loop	27-48-120
YELLOW	130 lb	25,000 Double Loop	27-48-130
BLUE	140 lb	25,000 Double Loop	27-48-140
RED	150 lb	25,000 Double Loop	27-48-150

Inside Diameter

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.

Wire Size

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.

End Type

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.