Weighing the door is the most reliable way to match the correct spring.
- Disconnect the opener and secure the door fully open.
- Remove the extension springs from the track supports so there is no spring tension.
- Place a bathroom scale under the center of the door and lower it slowly onto the scale.
- If the door exceeds one scale’s capacity, use two scales with a 2x4 across them and add the readings.
Use caution when lowering a heavy garage door. Have at least one other person assist to prevent the door from dropping suddenly.