Why does my garage door slam shut instead of closing slowly?

Controlled Descent Is the Spring's Job

A garage door is supposed to close the way an elevator descends: powered, governed, and boring. The opener only supplies the schedule; the springs supply the restraint, offsetting the door's weight so it never truly falls. When a door starts coming down fast and hitting concrete hard enough to rattle the windows, the counterbalance has failed somewhere, and the door is now partially in free fall with the opener straining to slow it. The candidates, roughly in the order we find them:

• A broken torsion spring. Look for the two-inch gap in the coil above the door and think back to whether anyone heard a gunshot-like bang from the garage recently. A door can limp along for days after a break before anyone connects the noise to the slamming.
• A fatigued spring that has quietly lost tension. No bang, no gap, just a door that has been getting faster on the way down for months. Common at the 7 to 10 year mark in our climate.
• A snapped or slipped cable. One slack or dangling cable means that corner has lost its connection to the spring system. The door often descends fast and slightly crooked. This pairs with the symptom in our answer on doors sitting higher on one side.
• On old extension-spring doors: missing or broken springs, or safety cables that are all that kept a broken spring from becoming a projectile.

Why You Park Outside Until This Is Fixed

Every slam is a couple hundred pounds arriving at the floor faster than designed, and three bad things compound. People and pets: a fast-closing door defeats the reaction time that safety systems assume, and the photo eyes only protect the bottom few inches of a beam line. The door itself: slam impacts crack panel sections, blow out bottom brackets, and shatter rollers, stacking a body-work bill on top of the spring bill. The opener: it was never built to be a brake, and braking a falling door strips gears and burns motors, which is how one broken spring becomes a spring, roller, and opener invoice. Until the repair, stop cycling the door. If it is up and must come down, one adult can pull the release and lower it under control with feet and hands clear, then leave it down and use the house door.

The Fix Is Fast, and Tonight Costs the Same as Tomorrow

Counterbalance repairs are bread-and-butter work: torsion spring replacement takes under 90 minutes including rebalancing; cable replacement is usually an even smaller job, priced by cable length and drum type; and we check drums, bearings, and the opener's condition in the same visit, with a free estimate before wrenches turn. Because a slamming door is a safety problem rather than a convenience problem, it qualifies for our 24/7 emergency service, and since 1994 we have never charged an after-hours surcharge anywhere in the metro, Oklahoma City to Mustang to Midwest City. Average response runs 20 to 50 minutes. Call (405) 247-0336 before the door takes one more fast trip down.