Garage door springs control the weight as it travels up and down. Without them the door would be very difficult to lift. If you see that your door opens or closes unevenly or too quickly, it is very likely that the springs are at fault.
How difficult is it?
The answer to this question depends on the style of the door springs you have. Some doors have side-mounted extension springs (easier to work with) while other doors have torsion springs (risky, because you work on them while they are under tension). Torsion springs are often left to professionals.
Find out the type of springs
Side-mounted extension springs can be seen above the overhead track, parallel to it. These springs are long and heavy, one on either side. You will notice the cable holding the spring. When the door is lowered the springs come under tension.
Torsion springs can be found just above the door. They extend along a metal shaft that runs parallel with the top of the garage door. On the end of the long round bar there are pulleys for the cables. The tension that the springs create makes it easier to lift the garage door. Typically, springs of this type are installed at the doors wider than 10 feet.
Torsion springs can be really risky if they are mishandled. It is often considered the most difficult type of garage door repair. So, only work with torsion springs if you are experienced enough and have reliable tools.
How to adjust side-mounted springs
Open the garage door until it hits the stop bolt. If it is an automatic door, unplug the opener and disconnect the door from it. Put a C-clamp below the bottom roller so that the door won’t move while you are working with it.
Find the large spring hook and remove it using an adjustable wrench. This will allow you to change the tension by placing the hook to another hole.
Decrease the tension if the door is difficult to close, does not seal, or opens too fast. To do this, just place the hook to a lower hole. Increase the tension (place the hook to a higher hole) if the door is difficult to open or closes too fast. Move the hook by one hole at a time and be sure to change the tension in both springs.
In case your door is closing unevenly, you will have to change the tension only on the side where the gap is.
Now it’s time to try the operation of the door. Unclamp the door and lower it. Does it close evenly? Has the gap disappeared? If yes, you’re done.