Broken Cable Repair in Dallas & the east metroplex

What the lift cables do and where they run

On a torsion door, a grooved drum sits at each end of the spring shaft above the opening. A steel aircraft cable winds around each drum, runs down the inside of the vertical track, and terminates at a bottom bracket bolted to the lowest corner of the door. When the springs unwind, they rotate the shaft, the drums take up cable, and the cable lifts the door. The cables carry the entire weight of the door in tension. They are not a secondary or a safety component; they are the connection between the counterbalance and the door itself, and when one fails that side of the door has nothing holding it.

Why cables fray at the drum

A cable does not wear evenly along its length. It wears where it bends under load. At the drum, the cable wraps a tight radius, and each cycle it lays into the groove, takes the full tension, and unwinds again, flexing the individual strands against each other and against the drum surface. Any misalignment makes it worse: a drum set screw that has crept loose lets the drum shift on the shaft, the cable then rides on the drum flange rather than seating in the groove, and it saws against the edge. The same principle applies at the bottom bracket, where the cable loops through a fitting and takes a sharp turn under full load. Those two points account for nearly every cable failure we see.

The other failure mode: a cable that came off rather than broke

If a closing door lands on an obstruction, whether that is a garbage can, a joist of lumber, or a car bumper, the door stops but the drums keep turning for a moment. The cable goes slack, comes out of its groove, and then re tensions in the wrong place, often wrapping over itself or dropping between the drum and the bearing plate. Nothing is broken at that point, but the door will lift unevenly and can jam. This is also why a door that sits crooked after someone left something in the doorway needs to be looked at rather than forced back into service. Re seating that cable and re setting drum tension is the actual repair.

The bottom bracket is where people get hurt

Both bottom brackets are under the full tension of the counterbalance whenever the door is closed, because that is exactly where the cables pull. Factory labels on those brackets warn against removing them, and the warning is accurate. If the bolts are backed out while the springs are wound, the bracket departs the door under load with the cable attached. Correct sequence is to unwind the springs with winding bars first, so the cables go slack, and only then work on the bracket. This is the same reason a broken cable is not a job to improvise on a Saturday: the intact side is still fully loaded.

Equal tension is what makes the door lift square

Replacing a cable is only half the job. Both cables have to be seated in their drums with the same number of wraps and the same tension, so that both bottom corners of the door lift at the same rate. If one drum is set even slightly differently, the door racks in the tracks on every cycle, which wears the rollers on the lagging side, marks the track, and eventually puts the door out of square permanently. Setting that tension involves loosening the drum set screws with the shaft locked, taking up the slack evenly on both sides, and re tightening onto the flats of the shaft. It is a fussy step and it is the difference between a repair that lasts and one that comes back.

What we check while the system is apart

Cable failure often leaves evidence elsewhere. The drum grooves may be scored where the cable rode out of place. The shaft can be scarred where a cable wrapped it. The bottom bracket rollers may be bent from the door dropping on one side. The vertical track frequently has a bright gouge or a bowed section where a roller was pulled sideways against it. Bearings get inspected because they are only accessible during this work. We report what we find with the reasoning, and we separate what needs replacing from what is simply cosmetic damage.