Springs · London
Extension Spring Replacement
You pulled the red cord to open the door during a power cut and it barely moved. Lifting it took your whole weight, and when you let go it came down hard.
Extension Spring Replacement
In plain words
Garage doors are balanced by one of two spring systems, and the extension kind is the one you find on many single-car doors and older detached garages. Instead of a spring wound on a shaft above the opening, an extension system uses two springs stretched along the horizontal tracks, working through pulleys and cables. It needs less headroom, which is why it suits garages with a low ceiling. Replacing these springs is its own service with its own parts: springs chosen by door weight, pulleys, S-hooks and containment cables. A technician confirms which system is on your door before any part is chosen.
How the visit goesThe door climbs with the left corner ahead of the right, then twists as it turns into the ceiling track. Looking up, the spring on the right side is stretched longer than its partner, with daylight showing between the coils.
London
How the visit goes
Torsion or extension, and which extension layout
The technician confirms the counterbalance type before choosing any part. Extension springs hang beside the horizontal tracks, one each side, with a pulley on the front end of each spring and a second, fixed pulley on the track angle near the door opening; the lift cable runs from the bottom corner over both. A torsion system has a spring on a shaft above the opening and belongs to a different service. Extension systems also vary: single or double springs per side on heavier doors, hangers fixed to the ceiling or to the rear track support, and cables that adjust at an S-hook, a clip or an eyebolt. Each affects the parts brought to the job.
Balancing the door by hand
Balance is judged with the opener still disconnected. The technician lowers the door to the floor, then lifts it: it should rise with modest effort, stay put when let go at about waist height, sit steady when fully open, and come down under control rather than dropping. If it sinks, both springs need a little more stretch and each S-hook is moved one hole to take up cable; if it climbs on its own, one hole the other way. Adjustments are always made in pairs, with the door open and clamped again each time, so the two springs stay equal. Two or three rounds usually settle it.
The numbers that stay with the door
Before leaving, the technician tells you what the door weighed, which spring rating and length went on, whether the pulleys and cables were renewed, and which hook position the cables were set to. Write it on a card by the opener or inside the door's manual. Extension springs are sold by rating and length, so the next set can be ordered from that card without weighing the door again, and a technician arriving later can see at a glance whether the door has been altered since. Add the date and roughly how many times a day the door is used; together those two facts give a fair idea of when the springs will be due again.
Extension Spring Replacement
In the van
- Rear spring hangers and angle iron
- Containment (safety) cables
- Lift cables
- Lag screws and hanger bolts
- Replacement rollers and hinges
What affects the quote
Same fees day, night or weekend
1Door weight and size
Spring rating follows the door's weight, and a wide insulated door or a wood door takes heavier springs than a light single. Weight and height together set the parts on the quote.
2How the door is sitting
A door resting closed with one spring gone is straightforward. A door stuck partway, twisted in its tracks or with a cable wrapped around a pulley has to be supported and straightened first.
3Condition of the lift cables
Cables with fraying, rust at the loop or a kink are renewed as a pair while the springs are off. Sound cables are re-routed and set, and the quote says which applies.
Extension Spring Replacement: questions
Would a stronger spring make the door easier to lift?
Not in a useful way. The aim is a spring that matches the door's weight, so the door holds still wherever you leave it. A spring rated above that weight pulls the door up on its own, makes it hard to close, and leans on the opener to hold it down. A spring rated below lets it sink. Matched springs, set to the same hook position, give the light, even feel you want.
My springs squeak and twang. Is that normal?
Some noise is ordinary. Extension springs stretch and relax on every trip, and a dry coil or a pulley with a dry axle will squeak, especially in cold weather; a light spray of lubricant along the springs and a drop on each pulley usually quiets it. A sharper twang, or a new grinding from a pulley, is worth a look, since a stiff pulley loads the spring and wears the cable.
Why does the door slam down the last bit?
A door that drops the final stretch is telling you the springs are no longer holding it. As an extension spring loses its temper it gives less pull near the bottom of travel, where the door needs the most support, so the door falls that last foot. Fresh springs matched to the door's weight bring the door down under control and take that shock off the bottom section and the opener.
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Extension Spring Replacement near you
Every garage door service we offer in London is described the same way: what you might have noticed, what the technician checks first, how the work is done and what you have afterwards. Start with the symptom you are seeing and the right service will be easy to find.