The numbers on the spring label (i.e. "P728") identify the spring with a part number. The letters P, SL or C before the numbers signify the type of spring end, either Plug, Safety Lock or Clip. The first number indicates the wire size and the next two numbers the length of spring. The letter “C” at the end of the number tells you the spring is equipped with safety connectors. For example, a P728C spring has plug ends, is made from #7 wire, is 28” long and has safety connectors. Remember when measuring a spring, measure from end of coil to end of coil, do not include the ends. Measure the springs only when they have been removed from the hardware set. The following identification marks are stamped on the top of the spring: UPC, part number (such as P728), maximum stretch, and safety warnings.
If your door is working properly, just replace your broken spring with the same type of spring. If there is no number on the plug or clip end of the spring, then determining the correct spring to purchase is obtained by calculating the spring’s outside diameter and the spring’s wire size. The wire size can be determined simply by measuring ten spring coils and then dividing this measurement by ten. Remember the best way to locate the proper spring is to find a comparable one on the spring rack.
The lower Jamb Connector (LJ-1P) lets you stretch the springs with a wrench. The Jamb Connector along with the Adjusta- Matic Kicker (AK-1P), allows you to adjust the leverage and tension of the hardware set without having to remove the springs.
The best alternative for the average homeowner is to recommend that they purchase the Lower Jamb Connector (LJ-1 P) and replace the chain. The LJ- 1P makes it much easier to adjust the stretch of the spring, because it allows the customer to use a screwdriver and/or wrench to make the adjustments. If the customer prefers to use the chain, the spring must be removed from the kicker in order to move the lower end of the spring up or down on the chain. The technique for removing or replacing the spring from the kicker requires good hand, leg, and back strength. To remove the spring from the kicker, the person must (1) straddle the springs with legs bent, (2) firmly grip the top of the springs, and (3) straighten the legs and pull up on the spring removing it from the kicker. The same technique is used to replace the spring.