Leveling Garage Doors

The purpose of this tutorial is to show how professional garage door installers and service technicians level smaller and lighter overhead-type sectional commercial and industrial, as well as residential, garage doors. These doors usually have a continuous hollow shaft running all the way across the top of the door. While heavier industrial doors have keyed solid shafts with a coupler that can be adjusted to level the door, lighter commercial and most residential garage doors do not have couplers for leveling the doors. These doors are leveled by rotating the cable drum on the side that is higher.

How to Level a Garage Door


We have also made a video to help you balance your garage door to provide you a more audio-visual option for learning how to level your garage door. Caution: The video was NOT designed to REPLACE the instructions below. The video is designed to INFORM the instructions. Protect yourself from serious injury and your property from further damage by reading all of the instructions below in addition to watching the video.

How to Level Your Garage Door

Using the form below, enter the size of the gap (in inches) under your garage door. For optimal results, make sure that you measure the distance from the garage floor to the garage door as close to the track and bottom bracket as possible. Additionally, you will need to compress any astragal or weatherstripping that is on the bottom of your garage door. After selecting your drum diameter and your shaft diameter, click the "Calculate" button. The three numbers you are given will help you to determine a more accurate measurement for step 4 in this tutorial. The angle θ is the rotation needed for the cable drum. The arc length is the distance around the shaft at which the two marks should be made. The chord length is the distance through space between the starting and ending points on the shaft. Caution: The chord length can be a less accurate measurement unless you understand how it corresponds to the angle of rotation.

θ (in degrees) =
Arc Length (on shaft) =
Chord Length (on shaft) =

The most common cause of overhead-type doors being out of level is frayed cables that grow in length as they fray. Doors also rise on one side when the cable is not properly seated on the cable drum on the opposite side. If the cable is not fitted properly on the drum or is frayed, this tutorial will not help you. You will need to either replace a cable or to reset a cable on one of the cable drums.

This is a dangerous procedure. Pay close attention to warnings that appear in red, including this one. If you question your ability to make this adjustment safely, hire a professional. Keep hands and clothing away from the shaft, torsion springs, and drums. For most who try this, the garage door gets worse before it gets better. Be prepared to have to rewind the spring or springs, especially on heavier doors.

1. SAFETY FIRST! To begin, turn off the power to the operator. Many operators are hardwired and have their own fuse or breaker box. You will need to turn off the power or maybe pull a fuse. Others are turned off at a breaker box with multiple switches that control power to other equipment as well. Many door openers are plugged into 110-volt outlets, and you can simply unplug them. Still, others have power switches above the operators. How to Level a Garage Door
How to Level a Garage Door 2. Use caution when on a ladder. While step ladders tend to suffice for residential work, you probably will need an extension ladder for commercial and industrial work. When you work on a ladder, always hook one of your legs through a rung on the ladder to stabilize yourself.

On this door, the gap is on the left side, but the door is lower on the right side, so the first adjustment to make is on the right side.

3. This door was lower on the right side because the cable drum had slipped on the right. So the first step is to secure the drum on the right side.

Climb the ladder and go up to the cable drum on the side of the garage that is lower and on the floor. Turn the set screws clockwise to tighten them as needed. When securing a cable drum to a hollow shaft, you will need to turn the set screws 3/4 turn past the point the set screw first meets the shaft.

How to Level a Garage Door
How to Level a Garage Door 4. In the next series of steps, you will move your ladder to the other side and climb up to the left cable drum.

Using a marker or file, mark the shaft and the drum. The mark on the shaft should be about 1/4" above the mark on the drum, as shown. If the gap under the door is less than one inch, make the marks 1/8" apart.

5. Vise grip the shaft so that the end of the vise grip is firm against the top of the garage door. We do this to keep the drum from turning too much and to keep the shaft from spinning if the set screws on both cable drums are too loose. How to Level a Garage Door
How to Level a Garage Door 6. Very slowly loosen one set screw. Watch the two marks. You want the two marks to line up, but don't loosen the set screw enough for the drum to move 1/4 inch. It will probably move at least 1/2 inch or more and create a worse problem on the other side of the garage door. Loosen the screw enough only until you see the first movement of the drum. Immediately, re-tighten the set screw 1/4 turn. Loosen the set screw again until you see the lower mark move and immediately re-tighten the set screw. Repeat this process of moving the drum in 1/16" increments until the two marks line up.
7. If the drum does not turn from loosening one of the set screws, tighten the first set screw halfway and loosen the other set screw following the same procedure as with the first set screw. Once the two marks line up, tighten the set screw just enough that the marks will stay where they are. How to Level a Garage Door
How to Level a Garage Door 8. After you tighten the set screw, check to see if the bottom of the door is level. If it is level, jump to step 12. If not, continue with the next step.
9. Add a second mark on the shaft just above the first mark as shown.

Release and reset the vise grip as in step five above.

How to Level a Garage Door
How to Level a Garage Door 10. Very slowly loosen one set screw again and follow the same procedure again in steps six through nine above.
11. Once the mark on the cable drum lines up with the new mark on the shaft, tighten the set screw enough to keep the marks together. If the bottom of the garage door is still not level, repeat this process following steps six through nine with another mark or marks until the door is level. Remember to release the vise grip each time you get to step nine. How to Level a Garage Door
How to Level a Garage Door 12. If the garage door is level, tighten the set screws 3/4 turn past the point at which they meet the hollow shaft. Heavier doors may require an additional 1/4 turn. Caution: Under-tightening the drums could cause the drum to slip and the door to cock or fall. Over-tightening the set screws could damage the shaft or drum, resulting in the same problems. This is a critical step.
13. Remove the vise grip from the shaft. How to Level a Garage Door
How to Level a Garage Door 14. Check the bottom of the garage door from the floor to verify that it is level.
15. Turn on the power to your operator. How to Level a Garage Door

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