Your garage door uses springs and cables to lift the weight of the door. The bottom of the door should sit one inch below the header of your garage door opening. This keeps tension on the cables preventing slack, which results in the cables coming off pulleys or drums. Stopping a garage door from opening too far depends upon whether you have an automatic door opener or if the door is a manual operation.
Position a step ladder under the back of the garage door opener, if you have an automatic door opener. Look for a small white screw with an arrow pointing up next to the screw.
Turn the screw 1/8 turn counterclockwise with a flat-head screwdriver. Open the garage door with your remote and check to see how far the door opens. Continue making adjustments as necessary until the door opens fully and there is tension on the door cables.
Find the up-limit push button, if your opener does not use a limit screw. There are two push buttons for the up-limit. One button has "Set" stamped on it and the button next to it has an upward pointing arrow.
Close the garage door with the remote control. Press and hold the up-limit "Set" button with your finger. The door will start opening. Release the "Set" button when the door is nearly fully open. The door stops moving when you release the button. Press and release the upward indicator button to fine-tune how far the door opens.
Insert a 2-inch long 1/2-inch diameter bolt into the hole on the rear of the upper track on each side, if you do not have an automatic opener. Insert the bolt from the outside of the track so the threads of the bolt are on the inside of the track.
Thread a nut onto each bolt and tighten with a wrench. The bolt shank prevents the door from opening too far by stopping the top rollers from advancing past.