How to Replace Gas Struts: Step-by-Step Guide
Replacing a gas strut requires checking the force rating in Newtons (N), prising off the old retaining clips, and clicking the new strut into the existing ball studs.
Introduction: Replacing Gas Struts Correctly
If an overhead cupboard door no longer stays open on its own or drops down unexpectedly, the gas strut is usually defective. Inside this component is nitrogen under high pressure. Over the years, minimal wear on the seals allows gas to escape, reducing the extension force. Repairing the strut is not technically possible – the component must be replaced.
This guide is aimed at installers and competent DIY enthusiasts. Replacement is a straightforward task that takes roughly 10 to 15 minutes per flap. The most critical part of this job is not the fitting itself, but identifying the exact replacement part beforehand.
Preparation: Choosing the Right Gas Strut
Before removing the old strut, you need to determine the specifications for the replacement. An incorrectly sized strut inevitably causes problems: if it is too weak, the flap drops down. If it is too strong, the cabinet door becomes very difficult to close, and the hinges may be ripped out of the carcass.
When selecting a new gas strut, pay attention to three key parameters:
- The force rating in Newtons (N)
- The total length (extended length)
- The stroke
A label is usually printed on the cylinder of the old strut (for example, "250 N" or "320N"). This value indicates the extension force. Always replace the strut with a model that has the exact same rating. For particularly heavy fronts made of MDF or solid wood, gas struts for heavy flaps are often used, which can feature ratings from 350 N to 500 N.
Measure the strut in its fully extended state. The measurement is taken from the centre of one mounting eyelet to the centre of the other mounting eyelet. Common lengths in cabinet making range between 245 mm and 270 mm.
The stroke describes the distance the piston rod can travel into the cylinder. It determines the maximum opening angle of the flap. This measurement is also specified in millimetres.
To maintain a cohesive look inside your cabinet, you can match the colour of the replacement fitting. Common finishes include gas struts in silver for standard carcasses, gas struts in black for dark decors, or gas struts in white for bright kitchen cupboards.
Required Tools and Materials
To simply replace the strut on existing brackets, you only need minimal tools. If you also need to replace the mounting plates on the carcass, the list expands slightly.
- Small flat-blade screwdriver (blade width approx. 3 mm to 4 mm) to lift the retaining clip.
- Folding rule or calliper to verify length dimensions.
- An assistant to support the open cabinet door.
- Optional: Cordless screwdriver with matching bit (usually PZ or PH) and a bradawl if the mounting brackets on the timber need to be replaced.
Instructions: Replacing a Gas Strut in 5 Steps
The cylinder of a gas strut functions like a closed air pump, where compressed gas constantly pushes the piston outward. Because this system is under tension, a methodical approach to dismantling is essential.
Step 1: Secure the cabinet flap
Open the cabinet door completely. As you release the mounting mechanism in the next step, the door will immediately lose its support. Ask a second person to hold the front securely in the open position. This prevents it from slamming down unexpectedly, which could damage the hinges at the top or cause injury.
Step 2: Lift the retaining clips
Most modern struts connect to the carcass and front via a ball joint. At the end of the strut (on the socket), there is a small, semi-circular metal retaining clip. Slide the blade of the flat screwdriver under this clip. Carefully prise the clip outward by about 2 mm to 3 mm. You do not need to remove the clip entirely – lifting it slightly is enough to release the internal locking mechanism.
Step 3: Pull off the old strut
While the clip is lifted, pull the head of the strut sideways off the ball stud. Repeat this process at the other end of the strut. The old cylinder is now fully removed. Take this opportunity to check that the remaining ball studs are firmly seated in the timber. If the screws are loose, tighten them using a manual screwdriver.
Step 4: Check the orientation of the new strut
Before fitting the new part, make sure the orientation is correct. The thick end (the cylinder) must point upwards when the flap is open, and the thin end (the piston rod) downwards. This orientation ensures that the oil inside the cylinder lubricates the seal on the piston rod. Incorrect installation leads to premature seal wear and renewed gas loss.
Step 5: Clip in the new strut
Attaching the new strut requires no tools at all. Position the socket of the strut over the ball stud on the cabinet at the correct angle. Press firmly on the fitting with your thumb until the retaining clip clicks into place with an audible snap. Repeat this process at the other end. Finally, test the operation by opening and closing the flap several times.
Avoiding Common Installation Mistakes
Even though the replacement seems simple, typical mistakes often occur in practice that impair the function of flap fittings.
Confusing strut types A gas strut must not be confused with a cabinet damper (soft-close cylinder). A gas strut actively pushes a flap upwards and holds it there. A soft-close damper, by contrast, only cushions a closing door. Traditional mechanical flap stays, which work via friction and are adjusted using an Allen key, are also a completely different system.
Misjudging the force rating DIYers often tend to choose a stronger strut "just to be safe". If the original strut was rated at 200 N, a 250 N strut is frequently fitted. This is a mistake. The leverage is calculated precisely for the weight of the front. A strut that is too strong constantly pushes the door slightly open when closed, creating an unsightly gap. It also puts undue stress on the carcass.
Testing the strut by hand A common misconception after unpacking a new strut is attempting to compress it by hand. With a force rating of, for example, 320 N (roughly equivalent to a lifting force of 32 kg), this is almost impossible to do manually. The fact that the strut cannot be moved by hand is not a defect. The system only operates smoothly once the leverage of the installed cabinet flap is applied.
Frequently Asked Questions (FAQ)
Do I always have to replace both gas struts on a flap? Yes, this is strongly recommended. If one strut weakens, the second has generally reached a similar lifespan. If you only replace one side, the new strut must carry most of the load on its own. As a result, it will wear out significantly faster. Furthermore, uneven force can cause the flap to twist.
How do I calculate the Newton rating if the print is illegible? If the label is missing, you must calculate the required force. As a rule of thumb for standard cabinet heights (approx. 300 mm to 400 mm): weigh the front. Allow roughly 10 N per kilogram of flap weight. For a 4 kg door, you need a total force of 40 N. As two struts are usually installed, you would choose two struts of 20 N each in this hypothetical case. In practice, values are often higher due to the laws of leverage. If in doubt, consult the manufacturer's charts.
Can gas struts be repaired or refilled? No. Gas struts are sealed systems under high pressure. Opening the cylinder is dangerous and technically impossible in a workshop. If pressure is lost, a complete replacement is mandatory.
Why does the door no longer open to the same angle after replacement? If the opening angle is no longer correct, you have fitted a replacement part with a different stroke or incorrect total length. Check the dimensions in mm once more. Accidental repositioning of the mounting plates on the timber also alters the geometry and therefore the opening angle.
Matching Components for Your Project
Overhead wall cabinets with flap doors are common in modern kitchens, often positioned directly above the sink where a plate rack for wall cabinets is installed. The hardware must work reliably in these locations due to rising moisture.
If you discover during the repair that the concealed hinges on the flap are also damaged, ensure you select hinges without an integrated self-closing mechanism, as these would otherwise work against the gas strut.