We used to have to know the weight of the door, and then using the total weight, any amount of added vertical lift, then using a torsion spring gauge which, looked like a small metal ruler, with a lip to tuck into the spring stock we carried, we would select the right diameter, gauge, and measure the length needed...cut it with a torch, and put the proper right, or left hand ends on them. Spring balance is sooo important.
We used to have to know the weight of the door, and then using the total weight, any amount of added vertical lift, then using a torsion spring gauge which, looked like a small metal ruler, with a lip to tuck into the spring stock we carried, we would select the right diameter, gauge, and measure the length needed...cut it with a torch, and put the proper right, or left hand ends on them.
Spring balance is sooo important.