My garage door was getting a bit heavy. It seems like I should have been doing maintenance on the door every 5 years or so, and did not know. The counter-balance to the double door are 2 torsion springs that give the door an assist on the way up.
These torsion springs are under tension. You need to get special 1/2″ diameter winding bars that insert into the holes, and then undo the two bolts that hold the spring to the main bar, then turn the winding bars to add tension, followed by retightening the two bolts. I strongly recommend the winding bars and no substitutes, but I did find some 1/2″ diameter bar in my garage, and it worked out tight enough.
I found the tightening of the torsion springs scary, so had to watch videos as others show me what to do. In the end it only took 30 tense minutes. I used a vice grip on the main bar to prevent it from moving. As I did the second side I moved the vice grip as well. A 3/8″ 12 point socket was too small, but the 7/16″ 12 point socket was good. After I initially loosened the bolts, they seemed to catch once slightly loose, so I had to loosen them again. In the end it worked out well, and now my door, in the closed position is pretty light.
This video is by far the best. It stresses safety, such as where to stand and what happens when things go wrong. It is obvious the guy knows what he is doing. This other video is also pretty good, but not as safety oriented.
I would not recommend this procedure unless you are good with tools and are strict about details and safety. Things can go wrong and you could be seriously hurt. This is a tense procedure, and one I am unfamiliar with. I had Little Weed in the garage, just in case I needed a call to 911 and a trip to the emergency room.
2019 Dec 08 I was taking apart a Chinese-made paper shredder that had died, and the two axles used for the paper cutters was exactly 1/2″ hex, 9 3/4″ long. Huh. I’ll need to stick them into my garage door bolts to see if they fit. Now I have an extra two winding bars, though I don’t know if they are long enough. I’ll keep them anyway!