Springs Sized to What a Wilmette Door Actually Weighs

Spring life is measured in cycles rather than years, a cycle being one trip up and one trip back down. Ordinary springs are built to somewhere near ten thousand. Divide that across two cars, a commute in each direction and a household that has not walked in through the front door since spring, and the arithmetic gets shorter than most owners assume.

On heavy doors the rating is worth deciding on before we order. Higher-cycle springs run thicker wire and a longer body and hold up far better on a door that works hard, while a detached garage opened twice a week is fine on standard ones. Whatever rating goes on, both springs are changed on a door that carries two. The pair came off the same shaft after identical service, so the intact one is running on whatever is left of the same lifespan.

When the springs are light for the door, the opener quietly makes up the difference, and you can hear it. The motor labors on the way up, the belt snatches at the start, and the door lands hard instead of settling. A year or two of that shows up as a chewed drive gear, a failed logic board, or cables fraying early because the drums take a shock on every close.

One test settles it. With the door halfway up, pull the release and take your hands away. A properly sprung door holds position. One that drifts toward the floor is under-sprung for its own weight, and on the heavier doors around Wilmette that single observation explains most of what the owner has been complaining about.