How to Replace Spiral Window Balances Safely
A single-hung or double-hung window that drops, sticks halfway or needs a shoulder to hold it open usually has a balance problem, not a window-frame problem. To replace spiral window balances properly, you need more than a similar-looking tube: the replacement must match the sash weight, tube length, diameter, fixing arrangement and spring tension of the original.
Spiral balances are common in older vertical sliding windows. They use a coiled spring inside a metal or plastic tube, with a spiral rod that connects to a sash shoe or pivot fitting. When both sides are correctly matched and tensioned, the balances carry the sash weight so the window opens smoothly and stays where you leave it. When one fails, the window can become difficult to operate or unsafe.
When to replace spiral window balances
A worn balance does not always look obviously damaged. The most common sign is a sash that will not stay open. It may slowly slide shut, slam down when released, or feel much heavier than it used to. A window that rises unevenly, binds in the frame or sits out of level can also point to one weak or broken balance.
Check for a missing or bent spiral rod, a cracked sash shoe, damaged tube, loose mounting screw or a balance that has pulled out of its fixing point. If the sash is heavy on one side, replace the balances as a pair. A new balance on one side and an old, tired balance on the other can leave the sash uneven and place extra strain on the remaining original part.
It is also worth checking the tracks, sash guides and weather seals. Dirt in the channel can make a sound balance appear faulty. Clean the frame channels first, but do not use grease or heavy oil inside the window tracks. These products attract grit and can make the problem worse over time.
Identify the correct replacement before removing anything
Spiral balances can look interchangeable when viewed in isolation, but small differences matter. The safest approach is to remove one existing balance carefully, keep it intact where possible, and compare the physical details.
Start with the tube length. Measure the body of the balance from end to end, excluding fittings unless the original manufacturer measurement clearly includes them. Then measure the outside diameter. Common diameters may be close enough to confuse by eye, yet a tube that is too wide can bind in the jamb and one that is too narrow may not sit correctly in its mounting position.
Next, inspect the lower end of the balance and the fitting at the sash. Spiral balance systems use different shoes, clips, brackets and hook arrangements. The colour of the spiral tip or tube may indicate a tension range on some systems, but colour alone is not a reliable way to order a replacement. Manufacturers have used different colour conventions, and previous repairs may have introduced a non-original part.
The sash weight is equally important. A balance with insufficient tension will allow the sash to fall. One with too much tension can make the window hard to close, pull the sash upward or overload the fittings. If the original balance has a part number or visible marking, record it. Take clear photos of the complete balance, both ends, the sash connection and the window profile before ordering.
For older Australian aluminium windows, the window brand and approximate age can also help narrow down the options. However, compatible fitment should always be confirmed from the hardware details rather than brand name alone. Window systems change over the years, including within the same manufacturer range.
Prepare the window and work safely
A spiral balance is spring-loaded. The spring tension is what supports the sash, so treat the repair as a controlled hardware job rather than a simple screw swap. If the sash is large, glazed with thick glass, or difficult to lift, use a second person. Property managers and trades should also consider whether the window is at height or forms part of a safety-critical opening.
Open the sash only as far as required to access the balances. Support its weight before disconnecting either side. Depending on the system, you may need to remove sash stops, release clips or tilt the sash out of the frame. Place a timber block beneath the sash or have an assistant hold it securely. Never rely on the remaining balance to carry the sash while you work on the first one.
Have a suitable screwdriver, pliers and measuring tape ready. A spiral balance winding tool is strongly recommended for systems that require the spiral to be tensioned or released. Trying to wind a spiral rod with ordinary pliers can damage the rod, slip unexpectedly or make it difficult to set equal tension on both sides.
How to replace spiral window balances
The exact sequence varies by window design, but the working principle is consistent. Remove and install one side at a time where possible, while keeping the sash supported throughout.
Remove the old balance without releasing control
Disconnect the balance from the sash shoe, hook or pivot fitting according to the existing arrangement. Hold the spiral rod with the proper tool before releasing any tension. Once controlled, unwind the rod carefully if required by the system, then remove the mounting screw or clip securing the tube in the jamb.
Do not force a tube that catches in the channel. Check for hidden retaining clips, paint build-up, debris or a fitting that needs to be turned before it can be withdrawn. Forcing the balance can damage the jamb lining or distort the replacement part you are trying to compare.
Fit the replacement in the same orientation
Install the new balance in the same position and orientation as the original. Secure the tube at its mounting point, then connect the lower fitting to the sash hardware. Ensure the spiral rod is straight and centred in the channel. A rod rubbing against the frame can wear prematurely and cause rough operation.
If the left and right balances are handed, do not swap them. Some systems are not handed, but others use fittings designed to sit on a specific side of the sash. Compare each replacement against the part removed from that side before installation.
Set even spring tension
The balance must be tensioned to support the sash weight. Use the winding tool to turn the spiral rod in the required direction, then engage it with the sash shoe or fitting while maintaining control. The number of turns depends on the balance type, sash weight and manufacturer specification, so copying the original setting is often the best starting point if the old balance was functioning reasonably before failure.
Set both sides evenly. Unequal tension can twist the sash, cause binding and make the lock difficult to align. After reconnecting the sash, raise and lower it slowly several times. It should stay open at practical positions without shooting upward or drifting down.
Test the whole window, not just the balances
Close and lock the sash after testing. The window should meet the frame squarely, engage the lock without force and operate without scraping. If it binds after replacement, check that the sash is seated correctly in both shoes and that neither balance has been installed under excessive tension.
A slight adjustment may be needed, but avoid repeated over-winding. If the sash is still too heavy despite correctly matched new balances, recheck the sash weight and tube specification. The issue may be incorrect part selection rather than insufficient turns.
Common mistakes that shorten balance life
The most frequent mistake is ordering by visual similarity. Tube length, diameter and end fittings need to match, while the correct tension is what makes the repair work. Reusing cracked sash shoes or worn pivot fittings is another false economy. These small parts transfer the load from the sash to the balance and can cause a new balance to fail early if they are damaged.
Avoid replacing only the visibly broken side unless the other balance is known to be recently replaced and in good condition. Balances work as a pair, and springs lose strength gradually. Replacing both at once gives more consistent sash movement and reduces the chance of another repair shortly after.
Finally, do not ignore a window that will not remain open after the job is complete. That is not a normal settling period. It indicates that the tension, fitment or related sash hardware still needs attention.
If you cannot identify the original balance confidently, clear photos and precise measurements can save time and avoid ordering the wrong part. The Glideworks team can help identify compatible replacement hardware from the details you can see, so you can get the sash operating smoothly and securely again.