Fasten The Door Bracket - Chamberlain LiftMaster 3275C Owner's Manual

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.
Fiberglass, aluminum or lightweight steel garage doors WILL
REQUIRE reinforcement BEFORE installation of door bracket.
Contact your door manufacturer for reinforcement kit.
Figure 1
Vertical
Reinforcement
Door
Bracket
Self-Threading
Screw
1/4"-14x5/8"
Figure 2A
HARDWARE
SHOWN ACTUAL
SIZE
Self-Threading
Screw
1/4"-14x5/8"
Figure 3
19
Header
Bracket
Door
Bracket
Location
HORIZONTAL AND VERTICAL
REINFORCEMENT IS NEEDED
Vertical
FOR LIGHTWEIGHT GARAGE
Centerline
DOORS (FIBERGLASS,
of Garage
ALUMINUM, STEEL, DOORS
Door
WITH GLASS PANEL, ETC.).
(NOT PROVIDED)
(Not Provided)
Vertical
Bolt
Centerline
5/16"-18x2"
of Garage Door
Door
Bracket
UP
(Not Provided)
Bolt
5/16"x2"
Vertical
Centerline
of Garage Door
Vertical
Centerline
UP
of Garage
Door
Self-Threading
Screw
1/4"-14x5/8"
Vertical
Reinforcement
Vertical
Centerline
of Garage Door
UP
Lock Washer
5/16"
Nut
5/16"-18
Figure 2B
Inside Edge
of Door or
Reinforcement Board
UP
Figure 4