Figure 2. Same door as in figure 1, but with required stiffener angle across top. Installation took 15
minutes. We use either 1/4x20x1" machine screws and NyLock nuts or 1/4"x 3/4" self
tapping sheet metal screws with integral lock washers (with fine threads).
Figure 3. Another door showing Stiffener Angle installed properly BUT lift motor installed OFF CENTER.
The obvious reason the lift motor system was installed off center was to avoid having to install
a STRUT across the space between the two ribs in the center of the door.
Figure 4. Adjacent door to figure 3, with lift motor moved to proper location so attachment point is
in the center of the door. Had this been done at time of original installation, this would
have added maybe 5 minutes to the install time. This fix eliminated almost all of the
"jerky" operation of these doors.
Figure 5. The top panel of this door was bent out about 6 inches as a result of long term use without the
required stiffener. The bending was so bad that a 2.5"x2.5" steel stiffener angle was required
to pull it back into "flat". Note the off-center connection point for the door lift which was a
partial cause of the bending problem. While adding the stiffener bar alone will go a long way
toward preventing bending and future problems, this door also needs to have the lift motor
attachment moved to the center of the door so stresses in this heavy door are balanced so
twisting of the door does not occur when the door is initially "jerked" into motion. Torsion bar
had to be adjusted to compensate for added weight of 2.5"x2.5" angle. (Adjustment NOT for