Spring replacement: when and how to find the right spring
How to spot a worn spring, measure an existing one, and find the correct replacement.
Mby Molas Online·June 18, 2026·5 min read
When to replace
Signs a spring needs replacing: loss of free length (a “tired” spring), cracks or fractures, corrosion, or a noticeable loss of force in the mechanism.
How to measure the existing spring
- Wire diameter (WD): use calipers on the wire.
- Outer diameter (OD): measure the widest part.
- Free length (FL): the spring under no load.
- Number of coils: count the full turns.
- End type: closed, ground or open.
- Wind direction: right hand (RH) or left hand (LH).
Material and finish
Whenever possible, replicate the original material. Music wire is common for general use; stainless for corrosive environments. Matching the material keeps the same spring rate and fatigue life.
With these measurements, enter the values in the designer, validate index and stress, and request an identical spring.
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