One Spring Broke — Should I Replace Both? The Honest Answer

What Happens When One Spring Breaks

Most modern two-car garage doors have two torsion springs mounted on a single shaft above the door. Both springs are typically installed at the same time and have the same age, the same fatigue history, and the same number of cycles on them. When one spring fails, it's because that spring reached the end of its effective service life — but the other spring has the same wear history and is at the same point in its lifecycle.

The question isn't whether the second spring is in better condition than the one that broke — it isn't, meaningfully. The question is whether the second spring has enough remaining service life to justify not replacing it. In most cases, the honest answer is no.

The Math on Dual vs. Single Replacement

A single torsion spring replacement runs priced after on-site assessment. A pair priced after on-site assessment. The incremental cost of replacing both is modest — quoted on-site based on your spring specification.

If you replace only the broken spring and the second spring fails 8 months later — which is the typical pattern — you pay for a second service call including diagnostic time, travel, and labor. The total cost of two single replacements done sequentially is almost always higher than replacing both in a single visit. And the second failure will occur at an unpredictable time, almost certainly an inconvenient one.

When Single Replacement Makes Sense

There are situations where replacing only the broken spring is a defensible choice. If the springs were replaced recently — within the last 3–4 years — the surviving spring has significantly more service life than one that's been running for 12 years. If the two springs were replaced at different times (which happens more often than people realize, especially after a previous one-spring replacement), they may have meaningfully different wear histories.

We tell you what we find. If the surviving spring appears to have significant remaining life based on its age and visible condition, we say so. We don't replace parts that don't need replacing to pad a service invoice. But when both springs are the same age and one has just failed, the honest recommendation is to replace both — and the reason is entirely about your interests, not ours.

The Balance Question

There is an additional technical reason to replace both springs simultaneously: door balance. Two springs share the load of counterbalancing the door weight. If one spring is new and one is old and partially fatigued, the two springs provide unequal tension on the torsion shaft — which creates a slight twisting force that puts uneven load on the cables, drums, and rollers. This is a minor issue in the short term but contributes to wear on related components over time.

A door with matched springs — both new, or both the same age — runs with better balance and less lateral stress on the cable drums.

The Bottom Line

Replace both springs when one breaks if both springs are the same age. The incremental cost is modest, the alternative is a predictable second failure at an unpredictable time, and the door operates better with matched springs. If your technician recommends both and can't explain why in terms you find satisfactory, that's a fair thing to ask about. A good technician will give you the honest answer — which is exactly what we just gave you.