Your garage door will have one of two types of garage door tension spring: torsion or side mounted spring. Because of the force behind a torsion spring, it is recommended that it is adjusted by a professional only. If your garage door tension spring is side mounted, you should have no problem adjusting it yourself.
Before You Start
You will need to open your garage door and make sure that it stays open while you are adjusting the tension spring. Open the garage door as far as it will go and clamp a c-clamp beneath the bottom roller. This will stop the door from closing. You will then need to remove any safety cables that are attached.
Adjusting the Garage Door Tension Spring
The springs will either be looped through holes in the track or attached with a special clip and S-hook. If the door closes too quickly, you will need to tighten the springs by tightening the cable through the loop or putting the S-hook in a closer hole. If the door is hard to open and close, loosen the spring by giving the rope some slack or placing the S-hook in a different hole to low for more slack.