Spring Measurement & Identification

Determine the spring type

Identify whether the system uses torsion springs (mounted on a shaft above the door) or extension springs (mounted along the horizontal tracks on each side). This determines how you measure and order replacements.

Measure the wire diameter

For torsion springs: count 10 coils and measure the total length. Divide by 10 to get the wire diameter (e.g., 10 coils measuring 2.50 inches = 0.250 wire). For broken springs, measure a single coil with calipers. For extension springs, measure the wire directly with calipers.

Measure the inside coil diameter

For torsion springs: measure the inside diameter of the spring coil (the gap inside the coils, not the outer diameter). Common sizes are 1-3/4", 2", 2-5/8", 3-3/4", and 4". For extension springs, measure the outside diameter of the coil body.

Measure the overall length

Measure the spring body from end to end (cone to cone for torsion, hook to hook for extension). Do not include the cones or hooks in the measurement. For broken torsion springs, add the two pieces together and subtract approximately 1 inch for the gap at the break.

Determine wind direction (torsion only)

Looking at the spring from the end, check which way the free end of the wire points: counterclockwise = right-wound, clockwise = left-wound. The winding cone color typically indicates direction: red = right-wound, black = left-wound. For duplex systems, one spring of each wind direction is required.

Record all measurements and cross-reference

Document: wire diameter, inside coil diameter, overall length, wind direction, and the number of springs on the system. Use the doorbot Spring Calculator or Spring Identifier tool to verify the IPPT and confirm the spring matches the door weight and height requirements.