Converting Extension Springs to Torsion: Will It Fit?

Extension springs — the long stretchy ones running above the horizontal tracks — built half the garages in America. They also whip like angry snakes when they snap, pull unevenly as they age, and need safety cables most older installs never got. The torsion conversion fixes all of it. One measurement decides whether it's a clean job.

The 12-inch rule

A torsion system needs room above the door opening for the shaft, springs, and drums. The rule of thumb: 12 inches of headroom from the top of the opening to the lowest obstruction. Measure to the lowest thing up there — a pipe or duct counts as the ceiling.

• 12"+ available: standard conversion, no drama.
• 9–12": standard torsion won't fit, but a low-headroom rear-mount kit (shaft mounted at the back of the horizontal tracks) usually will.
• Under 9": time for a hard conversation about hardware options.

DoorBot's Check Fit tab runs this exact verdict — punch in the measured headroom and door height and it tells you what fits, conversion included.

Why convert at all

• Safety: a torsion spring that breaks stays contained on its shaft. A broken extension spring without a safety cable becomes a projectile.
• Balance: one centered system instead of two independent springs that age at different rates and rack the door crooked.
• Lifespan and tunability: torsion springs come in precise IPPT increments and real cycle ratings; "stretchy" is not a spec.

Sizing the torsion springs

Forget the old extension springs — they tell you nothing useful. Torsion sizing starts from scratch with the actual door weight: weigh it or use the weight estimator, then let the spring sizer rank the options. A 16-footer should get a pair, not a single — here's why.

Scope the rest of the job

A conversion is more than springs: new center bearing plate, end bearing plates, shaft, drums, and cables, and the old extension hardware (springs, pulleys, sheave brackets) comes off entirely. The torsion-side work follows the standard torsion spring replacement procedure — with the usual warning, in bold, because it's earned: winding torsion springs is qualified-technician work.

Measure the headroom before you quote. It's one number, it takes ten seconds, and it's the difference between a standard conversion and a kit job at a different price.