Torsion Spring for Todco Overhead Door for Truck doors. Please select the size above that meets the needs of your Truck door Part # 51042 = 1-3/4" Counterbalance spring with winding & anchor plugs (plugs aka cones) Part # 59031 = 2-1/2" Counterbalance spring with winding & anchor plugs (plugs aka cones) Wire Size: Measure 10 coils and then 20 coils of the spring in the UNWOUND state. Find results on the chart below to determine which wire size you have
Length: Measure the furthest coil on left to the furthest coil on the right. Make sure you measure the length in the unwound state (if broken just put sections next to each other as if not broken). DO NOT include the cones (plugs) in your length measurement.
Inside Diameter:
There are two ways to find the inside diameter of a spring. You can measure across the break of the spring as shown on the left side of the graphic below. There is often a marker on the spring cones that indicates what the inside diameter is, as shown on the right side of the graphic below.