ASSEMBLY STEP 1
Attach the Rail to the Motor Unit
To avoid installation difficulties, do not run the
garage door opener until instructed to do so.
• Remove the two washered bolts mounted in top of
• Align rail and styrofoam over sprocket. Cut tape
from rail, belt and styrofoam.
• REMOVE STYROFOAM.
• Insert washered bolts through the rail into the
motor unit. Tighten bolts securely.
Use only these bolts! Use of any other bolts
will cause serious damage to door opener.
• Position belt over the motor unit sprocket.
To avoid SERIOUS damage to opener, ONLY use
bolts/fasteners mounted in top of motor unit.
ASSEMBLY STEP 2
Set the Belt Tension
• By hand, thread the spring trolley nut on the
threaded shaft until it is finger tight against the
trolley (Figure 1). Do not use any tools.
• Insert a screwdriver tip into one of the nut ring
slots and brace it firmly against the trolley
• Place a 7/16″ open end wrench on the square
end. Rotate about 1/4 turn until the spring releases
and snaps the nut ring against the trolley
This extends the spring for optimum belt tension.
ASSEMBLY STEP 3
Attach the Belt Cap Retainer
• Position the belt cap retainer over the motor unit
sprocket so the two holes in cap align with the two
holes in mounting plate. Attach with 8×3/8″ hex
You have now finished assembling your garage
door opener. Please read the following warnings
before proceeding to the installation section.
LiftMaster 3280 Model 3280 1/2HP 3280-267 1/2HP GARAGE DOOR OPENER