Chamberlain LiftMaster Security + 3270 1/2 HP Manuel D'instructions 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 lightweight 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 lightweight 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.
Figure 1
Figure 2A
HARDWARE
SHOWN
ACTUAL SIZE
Self-Threading
Screw 1/4"-14x5/8"
Figure 3
19
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
Vertical
Bolt
Reinforcement
5/16"-18x2"
Vertical
(Not Provided)
Centerline of
Garage Door
UP
Door
Bracket
Self-Threading
Screw 1/4"-14x5/8"
Vertical
Centerline
of Garage
Door
UP
Self-Threading
Screw 1/4"-14x5/8"
HORIZONTAL AND VERTICAL
REINFORCEMENT IS NEEDED
FOR LIGHTWEIGHT GARAGE
DOORS (FIBERGLASS,
ALUMINUM, STEEL, DOORS
WITH GLASS PANEL, ETC.).
(NOT PROVIDED)
Vertical
Reinforcement
Vertical
Centerline of
Garage Door
Door
Bracket
Lock Washer
Nut
5/16"
5/16"-18
Figure 2B
Inside Edge
(Not Provided)
of Door or
Bolt 5/16"x2"
Reinforcement
Board
Vertical
Centerline
of Garage
Door
Figure 4
UP
UP