Chamberlain 3255-2M 1/2 HP ユーザーズマニュアル

Fiberglass, aluminum or lightweight steel garage doors WILL
REQUIRE reinforcement BEFORE installation of door bracket.
Contact your door manufacturer for reinforcement kit.

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.

Vertical
Centerline

Door
Bracket
Location

Header
Bracket

HORIZONTAL AND VERTICAL
REINFORCEMENT IS NEEDED FOR
LIGHTWEIGHT GARAGE DOORS
(FIBERGLASS, ALUMINUM, STEEL,
DOORS WITH GLASS PANEL, ETC).
(NOT PROVIDED)

Door
Bracket

Vertical
Centerline
of Garage Door

Vertical
Reinforcement

Self-Threading
Screw 1/4"-14x5/8"

Self-Threading
Screw
1/4"-14x5/8"

Door
Bracket

Nut
5/16"-18

Bolt
5/16"-18x2"
(Not Provided)

Lock Washer
5/16"

Vertical
Reinforcement

Vertical
Centerline
of Garage Door

Self-Threading
Screw
1/4"-14x5/8"

Vertical
Centerline
of Garage Door

Inside Edge
of Door or
Reinforcement Board

Bolt
5/16"x2"
(Not
Provided)

Vertical
Centerline
of Garage
Door

Figure 1

Figure 2A

Figure 3

Figure 4

Figure 2B

HARDWARE
SHOWN
ACTUAL SIZE