Garage Door Closes Unevenly - Why It Happens and How to Fix It
One side hits the floor before the other. Or one corner never quite reaches the ground. Or the door shakes and wobbles as it comes down instead of traveling straight. All of these are versions of the same problem - the door isn't closing in a level, even path - but they have slightly different causes depending on exactly what you're seeing.
Let me go through each pattern.
One side hits the floor first
Door comes down and one corner touches the concrete before the other. Could be a half inch difference, could be more. You see a gap on one side when the door is "closed."
Spring tension is the most common cause. On a two-spring door, if one spring has more tension than the other, that side of the door is being pulled down harder and touches first. The other side, with less spring tension helping it down, lags behind.
Do the balance test. Disconnect the opener, lift the door to waist height, let go. Does one side drop faster or lower than the other? Consistently, not randomly - one specific side. That side has more tension or less resistance and the door is reflecting that asymmetry when it closes.
Cable issues cause the same pattern but more dramatically. If a cable is worn and stretching on one side, or came partially off its drum, that side travels differently. Look at both cables - they should be taut, evenly wound, no fraying.
Track angle mismatch - if one horizontal track section is angled slightly differently than the other, the door travels at different rates on each side through the curve. This is usually a mounting issue from original installation or from a bracket that shifted.
Gap on one side when door is closed
Door is "down" but there's a gap between the door bottom and the floor on one side. Light comes in. Drafts come through.
If the floor is uneven - sloped, cracked, or has a hump - even a perfectly adjusted door will have a gap somewhere. This is a floor issue not a door issue and the fix is a threshold seal mounted to the floor that fills the gap, not adjusting the door.
If the floor is level but the gap is there - bottom seal is torn or missing in that section, or the door itself is warped at that corner.
If the door is sagging at one corner - spring or cable issue as above.
Door wobbles or shakes coming down
Not an alignment issue exactly but related. Door moves unevenly, shakes side to side, makes noise as it descends.
Worn rollers are the usual cause. When rollers get rough or cracked, they don't guide the door smoothly through the track - especially at the curve where the horizontal section meets the vertical. The door kind of rocks through that transition instead of flowing.
Spin the rollers by hand with the door open. Any stiffness, wobble, or grinding - those are the ones causing it. A full set of replacement nylon rollers runs $20-40 and usually fixes the wobble completely.
Loose hardware also causes shaking. Hinge bolts that have backed out, track brackets that are slightly loose - the door has more play than it should and vibrates as it moves. Socket wrench around all the hardware, snug everything, and test.
Bent track at one specific spot. If the shaking or noise happens at the same point in the travel every time - same height, every cycle - look at the track right around that height. A slight bend or dent in the track causes the roller to bump through it each time. Tracks can be bent back carefully with a rubber mallet for minor issues, replaced for significant damage.
Door tilts as it opens or closes
Visibly tilted - not just a slight uneven close but actually angling as it moves, like one side is leading the other.
This is more dramatic and usually points to something structurally wrong. A cable that's off the drum on one side. A broken spring. A roller that's completely out of the track on one side so that section of the door is traveling without guidance.
Stop using the door if this is what you're seeing. A door that's tilting during travel is putting lateral stress on the tracks, the opener arm, and the rollers. Running it further makes more things bend.
Look at both cables, look at the spring, look at the rollers on the side that seems to be leading or lagging. Find what's missing or failed and address that first before running the opener again.
Fixing minor unevenness yourself
If the door is off by a small amount and everything looks physically intact - no broken spring, no cable issues, no roller out of track - a few things to try before calling anyone.
Check and tighten all the track brackets on both sides. Even a slightly loose bracket on one side lets that track shift position very slightly and can cause minor unevenness.
Check the rollers. Stiff rollers on one side create more resistance and the door naturally favors the easier path.
Check the bottom seal. If it's bunched or folded on one side it creates resistance at that corner and the door closes unevenly against it.
Lubricate everything. Dry parts on one side create friction that doesn't exist on the other side, causing the door to travel unevenly.
When to call someone
Any spring or cable issue - always call someone.
Visible tilt during operation - call someone.
Track damage that's more than a minor bump - call someone.
Everything looks fine but the unevenness persists - call someone. At that point it's a diagnosis job and someone needs to actually watch the door move to see where the problem is happening.
GarageDoorRepairz - if the door is closing unevenly and you can't pin down why, give us a call. We'll find it.
The role of the opener arm in uneven closing
Something people rarely think about - the opener arm connects the drive trolley to the door header bracket. If that arm is bent, adjusted incorrectly, or connected at an angle, it can pull the door slightly to one side as it operates.
Look at the opener arm when the door is closed. It should be straight, not visibly angled. The connection at the door header bracket should be centered. If the arm looks bent or the bracket connection is off-center, that's pulling the door unevenly on every cycle.
A bent opener arm usually happens from impact - someone backed into the door, the door was forced when something was wrong, or the trolley hit the end of the rail hard because the limit was set wrong. The arm absorbs that force and bends.
Replacement opener arms are available for most brands and aren't expensive. But before replacing it, check that whatever caused it to bend isn't still an issue - if the limit is set wrong and the trolley keeps slamming the end of the rail, a new arm will bend again.
Weather and seasonal effects on uneven closing
Steel expands in heat and contracts in cold. On a door that's borderline - springs just slightly off, track just slightly misaligned - temperature changes can push it from "fine" to "noticeably off."
A door that closes evenly in summer but leaves a gap on one side in winter is often a spring tension issue that's being exposed by the cold. The springs contract slightly in cold weather which changes their effective tension. A door that was balanced at summer temperatures may be slightly off when it's cold.
This doesn't mean the door needs a complete overhaul every season. It usually means the spring tension was slightly off to begin with and the seasonal shift is making it visible. Properly set spring tension handles normal temperature variation without causing visible unevenness.
Wooden doors are more affected by seasonal changes than steel because wood actually changes size with humidity - swells in humid weather, shrinks when it's dry. If you have a real wood door and it's closing unevenly only at certain times of year, the door material expanding or contracting is a factor separate from the hardware.
Checking the floor before assuming it's the door
Before adjusting anything on the door for a gap issue - check the floor with an actual level. Put a 4-foot level on the concrete where the door closes and see whether the floor is actually level across the full width.
Garage floors often aren't perfectly level. They're poured with a slight slope toward the drain, they settle unevenly over decades, they crack and shift. A floor that's a quarter inch lower on one side will create a quarter inch gap on that side no matter how well adjusted the door is.
If the floor is the issue, the fix is a threshold seal rather than chasing door adjustments that won't help. Threshold seals are mounted to the floor and fill the gap from the floor side - much more practical than trying to adjust the door to match an uneven floor.
GarageDoorRepairz - give us a call if the door is closing unevenly and you want someone to actually diagnose what's causing it rather than guessing.