Springs · Toronto
Extension Spring Replacement
A bang like a dropped toolbox came from the garage last night.
In plain words
Every extension spring should carry a containment cable, and replacement is the moment to make sure yours do. A containment cable runs through the centre of the spring and is anchored at both ends, to the rear hanger and to the bracket at the front of the track. It does no lifting; its purpose is to hold a spring that breaks so the pieces stay on the cable. Many older doors predate this practice, which a home inspection checklist checks for. When springs are replaced, new containment cables are fitted with them, which keeps a broken spring's pieces contained, not the door's weight, balance or safety.
How the visit goesIt is the first hard frost of the year and the door on the old detached garage has stopped halfway, squealing at one pulley. The springs are the ones that came with the door decades ago, orange with rust where they hang near the back wall.
Extension Spring Replacement
How the visit goes
Pulleys, cables and the hooks that set them
Each side of an extension system has two pulleys, one on the moving end of the spring and one fixed at the front of the horizontal track, and a lift cable that runs from the bottom bracket over both to an S-hook or clip on the track hanger. Each pulley is spun to feel for a rough bearing and looked at for a wheel worn to a sharp groove or wobbling on its bolt. The cables are followed for fraying, rust at the bottom loop and a wrap that has slipped off a pulley. Worn pulleys and cables are renewed with the springs, since a seized pulley is often what shortened the old spring's life.
Setting both sides to the same hole
The initial tension is set with the door open and clamped, so the technician is adjusting slack springs rather than loaded ones. Each cable's S-hook is placed in a hole on the hanger, or its clip set to a mark, and the two sides are put at the same position. The cables are drawn to the same snugness so that neither corner of the door is being pulled ahead of the other. A level across the top section confirms the door is square in its tracks. Only when both sides read the same do the clamps come off and the door come down for its first balance check.
Containment cables, and leaving them be
Your door now has a cable running through the middle of each spring, anchored at the back hanger and at the front of the track. It carries no meaningful load while the springs work, though a trace of slack as the door cycles is normal. Its job begins only if a spring ever breaks, when it holds the pieces on the cable instead of letting them fly. It should not be removed, used to hang anything, or tied back to the wall. If it ever looks badly slack, frayed or pulled from its anchor, call to have it corrected promptly rather than waiting for a routine visit. A home inspector looks for this cable when a house is sold.
Extension Spring Replacement
In the van
Containment (safety) cables
Bottom brackets and clevis pins
Extension springs, matched pair
Lift cables
Rear spring hangers and angle iron
Extension Spring Replacement
What affects the quote
Track or section damage found on the way
A bent horizontal track, a bracket pulled off the jamb or a top section twisted by running the opener on a broken spring is separate repair work, quoted on its own.
Corroded fasteners
In an unheated garage the bolts through pulley forks and hanger brackets rust solid; freeing or cutting them and fitting new hardware takes time and shows in the parts list.
Containment cables to add
A door that never had containment cables gets them with the new springs, along with anchor hardware into the framing. It is a small parts line and a worthwhile one.
What to have ready
- Is a spring broken in two, hanging loose, or just looking stretched?
- Is a car parked inside that will need to come out first?
- Is the door closed, fully open, or stuck partway?
Extension Spring Replacement: questions
QuestionsWhat can I do to make the new springs last?
Three things. Spray the springs, pulley axles and hinges with a garage-door lubricant twice a year, which slows rust in an unheated garage. Keep the threshold clear of bins and packed snow so the door never stops short with the springs still pulling. And leave the opener's force setting where the technician put it, since a door that starts needing more push is a balance question rather than a dial to turn.
Only one spring broke. Why replace both?
The two springs are the same age and have stretched the same number of times, so the one still hanging is close behind. There is also a balance reason: a door lifts level only when both sides pull equally, and a new spring beside a worn one lifts its corner first and twists the door. Fitting a matched pair sets both sides the same and avoids a second visit a few months on.
What is the difference between extension springs and torsion springs?
They balance the door in different places. Extension springs are the two long coils that run beside the horizontal tracks and stretch as the door closes; they work through pulleys and cables. A torsion spring is wound on a shaft above the door opening and turns drums that wind the cables. The parts, the way tension is set and the service itself are different, so it helps to say which you have when you call.
