A roll-up door spring must match the weight and operating arrangement of the door curtain. Door size alone is not enough to confirm the correct spring.
Before you place a new or replacement order, check the wire size, inside diameter, body length, winding direction and end design. These details determine whether the spring can fit and work with the existing door assembly.
What Is a Roll-Up Door Spring?
A roll-up door spring counterbalances the curtain as the door opens and closes. Depending on the door design, the spring may be fitted around an axle or installed inside a barrel or torque-tube assembly.
The spring works together with the axle, mounting hardware and door curtain. A spring that fits around the axle is not automatically suitable for the door. Its torque, winding direction and end connections must also match the system.
This is why you should identify the complete spring specification before comparing prices or approving a replacement.
Roll-up door springs should not be confused with the torsion and extension systems used on sectional garage doors. If you are specifying a sectional door instead, see our guide to garage door spring types.
Key Roll-Up Door Spring Specifications
Roll-up door springs can look almost identical while having different operating characteristics. Check each of the following specifications separately.
Wire Size
Wire size is the diameter of the steel wire used to form the spring. It has a direct effect on spring torque and working stress.
Use a caliper or another suitable measuring tool rather than estimating the dimension with a ruler. If you do not have the original specification, measure several points and check that dirt, wear or surface coating is not affecting the result.
A small difference in wire size can produce a meaningful difference in spring performance. We would not recommend substituting the nearest available wire size without reviewing the complete spring design.
Inside Diameter
Inside diameter is measured across the clear space inside the spring coil. It must suit the axle, tube or mounting arrangement used by the roll-up door.
Make sure you provide the inside diameter rather than the outside diameter. Two springs with a similar external appearance may use different combinations of wire size and inside diameter.
For a replacement order, include a photograph showing how the measurement was taken. This makes it easier to identify whether the stated dimension is an inside or outside measurement.
Spring Body Length
Spring body length normally refers to the coiled section of the spring. Do not include hooks or other formed ends unless the drawing specifically requests an overall length.
Measure the spring when it is relaxed and safe to handle. If the spring is broken, place all sections together and record the combined length of the coiled body. You should still provide photographs because the damaged spring may have become distorted.
Do not estimate the required body length from the door height alone. Spring length must be considered together with the wire size, inside diameter and required torque.
Winding Direction
Roll-up door springs may be left-hand wound or right-hand wound. The correct direction depends on the spring position and how torque is applied in the door assembly.
Do not identify winding direction from the installation side alone. The terms “left” and “right” can be misunderstood when the spring is viewed from opposite ends.
Provide a full-length photograph of the spring and mark its original position. If the door uses several springs, label each one separately.
End Design
The spring ends connect the coil to the axle, bracket, disc or other mounting component. Their shape, direction and dimensions are part of the spring specification.
Two roll-up door springs may have the same wire size, inside diameter and body length but use different hooks. They should not be considered interchangeable unless the end connections also match.
For a replacement order, photograph both ends separately. A side view is useful for showing the hook shape, while an end view helps confirm its direction and position relative to the coil.
Spring Quantity and Position
Record how many springs are installed on each door and where they are positioned.
If several springs are fitted to the same axle, do not assume that every spring has the same specification. Mark the position, winding direction and dimensions of each spring before requesting a replacement set.
Material and Surface Finish
Oil-tempered and powder-coated do not describe two equivalent spring types.
Oil tempering relates to the spring wire and its processing. Powder coating is a surface finish applied to the spring. A powder-coated roll-up door spring may still be manufactured from oil-tempered wire.
Confirm the wire material and surface treatment as separate specifications. The coating does not determine the torque or cycle life of the spring; these depend on the complete spring design and working stress.
How to Measure a Roll-Up Door Spring
Before you measure a replacement spring, photograph it in its original position. If your door uses several springs, label each one separately so the measurements are not mixed.
Measure the Wire Size
Use a caliper to measure one wire on a clean, undamaged section of the coil. We recommend checking two or more positions rather than relying on one reading.
Record whether your measurement is in inches or millimetres. If you do not have a caliper, measure several closed coils together and divide the total width by the number of coils. Do not simply choose the nearest catalogue size.
Measure the Inside Diameter
Measure across the clear opening inside the spring, from one inner edge to the opposite inner edge. Keep your caliper perpendicular to the spring body and avoid measuring across the hook.
If your spring is distorted, take two measurements at right angles and provide both results. Make sure you record the inside diameter rather than the outside diameter.
Measure the Spring Body Length
Measure from the first complete coil to the last complete coil, excluding the formed ends. If you also measure the overall length, label the two dimensions clearly.
Your spring should be relaxed before measurement. If it is broken, place all sections in their original order, record the combined coil-body length and include photographs of the damaged areas.
Confirm the Winding Direction and End Design
Do not identify the winding direction only from where the spring is installed. We recommend taking an end-view photograph and comparing it with the supplier’s left-hand and right-hand winding reference.
Photograph both ends separately. Your supplier needs to see the hook shape, direction and connection position, as springs with the same coil dimensions may still use different ends.
Record the Quantity and Axle Diameter
State how many springs your door uses and mark the installed position of each one. You should also measure the outside diameter of the axle or tube around which the spring is fitted.
For an accurate review, send photographs of your complete spring, both ends, the main measurements and its original installation position.
Roll-up door springs store considerable energy. Only take these measurements after the spring has been safely released or removed by trained personnel
How Do You Select the Correct Roll-Up Door Spring?
The selection method depends on whether the spring is intended for a new door or an existing assembly.
For a New Roll-Up Door
Start with the actual or calculated weight of the moving curtain. You should also confirm:
- Door width and height
- Curtain material and thickness
- Bottom-bar construction
- Axle or tube dimensions
- Spring mounting arrangement
- Required operating cycles
Do not select the spring from the opening size alone. Two doors with the same width and height can use different curtain materials and may therefore require different spring specifications.
A practical rule is to finalize the curtain weight and axle arrangement before approving the spring. If either of these changes, review the spring calculation again.
For a Replacement Roll-Up Door Spring
The existing spring provides a useful starting point. Measure its wire size, inside diameter, body length, winding direction and ends, then compare those details with the original installation.
Copying the old spring may be reasonable when the door previously operated correctly and its configuration has not changed. However, request a fresh technical review if:
- The door was difficult to open or close
- The curtain did not remain properly balanced
- The door curtain or bottom bar was modified
- The axle assembly was changed
- The original spring failed unexpectedly
- The required operating frequency has increased
In these situations, reproducing the old spring may reproduce the same balance or service-life problem.
Information Needed to Match a Roll-Up Door Spring
To match a roll-up door spring, provide the wire size, inside diameter, body length, winding direction and clear photographs of both ends.
For new door production, also include the door dimensions, curtain weight and axle or tube diameter. If your enquiry contains several spring specifications, label each spring, drawing and photograph with a separate reference number.
Frequently Asked Questions
Are Roll-Up Door Springs Universal?
No. Roll-up door springs differ in wire size, inside diameter, body length, winding direction and end design. They must also suit the door load and axle arrangement.
How Do You Measure a Roll-Up Door Spring?
Measure the wire size, inside diameter and relaxed coil-body length. You should also identify the winding direction, end design, spring quantity and original installation position.
Can You Order a Roll-Up Door Spring by Door Size?
Door size alone is not enough. Curtain weight, axle dimensions, spring ends and mounting arrangement also affect the required specification.
Can You Copy an Existing Roll-Up Door Spring?
You can use the existing spring as a reference if the door previously operated correctly and its configuration has not changed. If the old spring failed unexpectedly or the door was poorly balanced, the specification should be reviewed before it is reproduced.
What Photographs Should You Provide?
Provide one complete spring photograph, close-ups of both ends, photographs of the wire-size and inside-diameter measurements, and an image showing the original installation position.
Final Thoughts
The correct roll-up door spring must match both the measured spring specifications and the door assembly. Do not select a replacement from its appearance or door dimensions alone.
Send your spring measurements, installation photographs and required quantity to Gemax for specification review and quotation.
