One Side of the Garage Door Is Lower Than the Other: How to Diagnose and Correct Cable Slack
It is easy to spot when one side of the garage door is lower than the other. You close your door and notice an obvious wedge of daylight glowing underneath one corner, or the door looks slanted as it rolls up the tracks. An uneven garage door is more than just a cosmetic annoyance. It means the intricate weight distribution system holding your door up has slipped or broken.
Continuing to use a crooked door places incredible diagonal stress on the tracks, the rollers, and the opener motor itself. Eventually, the door will jam entirely or derail, converting a manageable adjustment into a massive repair bill. This guide covers how to diagnose the cause of an uneven garage door and how to address the usual culprit: garage door cable slack.
Why One Side of the Garage Door Is Lower Than the Other
Sectional garage doors in Australia rely on a torsion spring system connected to heavy-duty lift cables on both sides. The spring provides the lifting force, and the cables physically pull the door up from its bottom corners. If everything is balanced perfectly, the door rises completely level. When it does not, you are looking at one of three primary failures.
1. Garage Door Cable Slack on One Side
This is the most common reason for a crooked door. Over time, lift cables can stretch slightly. Sometimes, if the door hits an obstruction like a broom or a bucket while closing, the cable on the opposite side momentarily loses tension. This brief slack allows the cable to slip and overlap incorrectly on the cable drum located above the door.
When the cable wraps poorly around the drum, it effectively becomes longer on one side than the other. The side with the slipping or overlapping cable will hang lower because it is not being pulled tight with the same lifting force.
2. A Frayed or Snapped Lift Cable
In harsh Australian coastal environments, the steel fibres of lift cables can succumb to rust and fraying. If enough steel strands break, the cable physically elongates under the intense weight of the door. If the cable has snapped entirely, that entire side of the door is dead weight, held up only by the rollers twisting in the track. You will instantly notice one side dragging heavily if this happens.
3. A Broken Torsion Spring
If you have a double garage door, it likely has two torsion springs mounted beside each other on the centre shaft. If one spring snaps, you lose half your lifting power. The side directly associated with the broken torsion spring unlevel door issue will slump noticeably, and the opener will struggle violently to lift the door against the unbalanced weight.
How to Diagnose and Correct the Issue
Diagnosing an uneven door is straightforward but requires caution. Never stand directly beneath a tilted garage door, as it is structurally unstable.
Step 1: Perform a Visual Inspection
With the door fully closed, look up at the torsion springs. Are they fully intact or is there a visible break in the coils? Next, take a torch and look at the cable drums at the top corners of the door opening. Ensure the cable is resting neatly in the grooves of the drum. If the cable looks tangled, or if there is obvious garage door cable slack hanging loosely down the side of the track, you have found the problem.
Step 2: Securing the Door (For Professionals)
To fix crooked garage door cable slack, the tension must be completely removed from the spring system. This requires locking the torsion shaft with specialised tools and manually re-winding the cable onto the drum in the correct grooves. The drum set screws must then be tightened to ensure the cable does not slip again.
If a cable is frayed, both cables should be replaced simultaneously to ensure they stretch evenly in the future.
Why You Should Avoid DIY Cable Repairs
Re-tensioning cables involves working directly with torsion springs. These springs hold enough stored kinetic energy to easily crush hands, break bones, or cause fatal injuries if a winding bar slips. Because the entire weight of the door is resting unevenly on these components, attempting an amateur uneven garage door repair Australia homeowners often try will likely result in the door crashing to the ground or the spring unwinding violently.
Learn more about how your hardware works in our garage door knowledge hub. If your door is crooked, the easiest and safest choice is to call a professional. Opal Garage Doors provides expert garage door repairs. We will safely reset your cable tension, replace worn hardware, and rebalance your door perfectly. Contact us to secure an inspection today.