Chamberlain 84505R - Garage Door Opener Assembly Guide; Attach Belt Rail to Opener; Tighten the Belt

10
Assembly
1 Attach the Belt Rail to the Garage Door Opener
87504-267, 84505R
To avoid possible SERIOUS INJURY to finger from moving garage door opener:
•
ALWAYS keep hand clear of sprocket while operating opener.
•
Securely attach sprocket cover BEFORE operating.
To avoid SERIOUS damage to garage door opener, use ONLY those bolts/fasteners mounted in the top of
the opener.
NOTE: ONLY use the bolts removed from the garage door opener. Place the garage door opener on the packing
material to prevent scratching.
1. Models 87504-267 and 84505R Remove the two bolts from the top of the garage door opener.
2. Align the holes in the rail with the holes in the garage door opener..
3. Fasten the rail with the previously mentioned bolts. Cut away and discard the tape and Styrofoam from
around the rail.
4. Position the belt around the garage door opener sprocket.
5. Position the sprocket cover over the garage door opener sprocket and attach with hex screws.
Hex Screw
#8x3/8"
(Packed with the
belt cover)
HARDWARE
Washered Bolt 5/16"-18x1/2"
(Mounted in the garage door opener)
Models 87504-267, 84501
Washered Bolt
5/16"-18x1/2"
Hex Screw
#8x3/8"
2 Tighten the Belt
1. Insert a flathead screwdriver tip into one of the nut ring slots and brace it firmly against the trolley.
2. Tighten the spring trolley nut with an adjustable wrench or a 7/16" open end wrench about a quarter turn
until the spring releases and snaps the nut ring against the trolley. This sets the spring to optimum belt
tension.
Spring Trolley Nut
(To motor unit)
Nut ring
slot
Nut Ring
Nut Ring
AFTER RELEASE
1-1/4"
(3.18 cm)
BEFORE
1"
(2.5 cm)
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