There are specific types of garage doors that will need to be leveled. These doors are typically lighter and smaller and are overhead versions. The garage doors that need leveling will have a hollow shaft that is found along the top of the door. These lighter doors do not have an automatic adjuster for leveling so you will have to take care of this yourself.
Step 1: Calculate the Distance
Before you begin leveling your garage door you need to determine the size of the gap underneath your door. You also need to know the shaft diameter and the drum diameter. There are two different ways to calculate the length of the chord.
To calculate, measure the starting and ending distance that the shaft will travel. You also can calculate the arc angle though this will require a scientific calculator with SIN functions.
Step 2: Replace Cables
Be aware that as cables get old they will fray and stretch so you need to make sure your cables are not frayed. You will need to replace the cables first before leveling the door otherwise you will not have any success with the following directions.
Step 3: Turn off the Electricity
The very first thing to do is to turn the power off. Unplug the garage door from the source or turn the circuit breaker off. This ensures that under no circumstances will the door turn on.
Step 4: Making the 1st Adjustment
Start with the side which is opposite to where the gap is. So with a gap on the left side, you will begin leveling on the right side. To rise the side of the door that is lower turn the set screws in the drum clockwise. This will tighten the screws and raise the door. Make marks on the shaft to ensure you turn the screws far enough.
Step 5: Moving to the Other Side
Now move to the other side of the door. Mark the shaft in its present position, mark the drum and the shaft. The shaft mark is about ¼ of an inch above the drum mark. If the gap is small under the door, less than one inch, then the marks should be 1/8 of an inch apart.
Step 6: Stabilizing the Shaft
Use a vise grip in the shaft to stabilize it. Wedge the end of the vise grip to the top of the door. This will ensure that the drum does not move too much as the drum can start spinning a lot if the set screws are very loose. Slowly loosen the set screw and let the two marks line up. Now loosen and tighten the two screws slowly until this point is met.
Step 7: Check the Level
At this point, check your door to make sure it is level. Completely tighten all the screws but be careful not to over tighten them as this can damage the shaft. Take off the vise grip and turn on the power.