LiftMaster 3255 3255 Manual - Page 19

INSTALLATION STEP 11 Fasten the Door Bracket Follow instructions which apply to your door type as illustrated below or on the following page. A horizontal reinforcement brace should be long enough to be secured to two or three vertical supports. A vertical reinforcement brace should cover the height of the top panel. Figure 1 shows one piece of angle iron as the horizontal brace. For the vertical brace, 2 pieces of angle iron are used to create a U-shaped support. The best solution is to check with your garage door manufacturer for an opener installation door reinforcement kit. NOTE: Many door reinforcement kits provide for direct attachment of the clevis pin and door arm. In this case you will not need the door bracket; proceed to Step 12. SECTIONAL DOORS 1. Center the door bracket on the previously marked vertical centerline used for the header bracket installation. Note correct UP placement, as stamped inside the bracket. 2. Position the top edge of the bracket 2"-4" (5-10 cm) below the top edge of the door, OR directly below any structural support across the top of the door. 3. Mark, drill holes and install as follows, depending on your door's construction: Metal or light weight doors using a vertical angle iron brace between the door panel support and the door bracket: • Drill 3/16" fastening holes. Secure the door bracket using the two 1/4"-14x5/8" self-threading screws (Figure 2A). • Alternately, use two 5/16" bolts, lock washers and nuts (not provided) (Figure 2B). Metal, insulated or light weight factory reinforced doors: • Drill 3/16" fastening holes. Secure the door bracket using the self-threading screws (Figure 3). Wood Doors: • Use top and bottom or side to side door bracket holes. Drill 5/16" holes through the door and secure bracket with 5/16"x2" carriage bolts, lock washers and nuts (not provided) (Figure 4). NOTE: The 1/4"-14x5/8" self-threading screws are not intended for use on wood doors. HARDWARE SHOWN ACTUAL SIZE Self-Threading Screw 1/4"-14x5/8" Fiberglass, aluminum or lightweight steel garage doors WILL REQUIRE reinforcement BEFORE installation of door bracket. Contact your door manufacturer for reinforcement kit. Header Bracket Door Bracket Location Vertical Centerline of Garage Door HORIZONTAL AND VERTICAL REINFORCEMENT IS NEEDED FOR LIGHTWEIGHT GARAGE DOORS (FIBERGLASS, ALUMINUM, STEEL, DOORS WITH GLASS PANEL, ETC.). (NOT PROVIDED) Figure 1 Vertical Reinforcement Vertical Centerline of Garage Door UP Door Bracket Self-Threading Screw 1/4"-14x5/8" Vertical (Not Provided) Reinforcement Vertical Centerline of Garage Door Bolt 5/16"-18x2" UP Door Bracket Lock Washer 5/16" Nut 5/16"-18 Figure 2B Figure 2A (Not Provided) Bolt 5/16"x2" Inside Edge of Door or Reinforcement Board Vertical Centerline of Garage Door UP Figure 3 Self-Threading Screw 1/4"-14x5/8" Vertical Centerline of Garage Door UP Figure 4 19