LiftMaster 3850 3850 Elite Series Manual - Page 11

INSTALLATION STEP 4 Position the Opener Follow instructions which apply to your door type as illustrated. SECTIONAL DOOR OR ONE-PIECE DOOR WITH TRACK A 2x4 laid flat is convenient for setting an ideal door-to-rail distance. • Raise the opener onto a stepladder. You will need help at this point if the ladder is not tall enough. • Open the door all the way and place a 2x4 laid flat on the top section beneath the rail. • If the top section or panel hits the trolley when you raise the door, pull down on the trolley release arm to disconnect inner and outer sections. Slide the outer trolley toward the motor unit. The trolley can remain disconnected until Installation Step 12 is completed. To prevent damage to garage door, rest garage door opener rail on 2x4 placed on top section of door. Rail Door 2x4 is used to determine the correct mounting height from ceiling. ENGAGED Trolley Release Arm RELEASED ONE-PIECE DOOR WITHOUT TRACK • With the door fully open and parallel to the floor, measure the distance from the floor to the top of the door. • Using a stepladder as a support, raise the top of the opener to this height. • The top of the door should be level with the top of the motor unit. Do not position the opener more than 4" (10 cm) above this point. Header Bracket Top of Motor Unit Top of Door 2x4 is used to determine the correct mounting height from ceiling. 11