Extension Spring Pulley Replacement

One major cause of failure for garage doors using extension springs is that the pulleys wear out. Usually, the ball bearings break down, causing the pulley to scrape against the track angle, or the rivets fail, and the pulley splits as in the picture above, causing the door cable to stick.

When the owner of this garage door called us she said, "The garage door opens part way and stops." This is one of the many symptoms caused by worn pulleys. This particular door would not sit evenly on the garage floor when we tried to open it, the garage door jammed.

Generally, when pulleys fail, the garage door does not open and close properly. The garage door closes part way and reopens. The door binds and sticks, and scraping sounds often accompany the other symptoms. Sometimes the first symptom is a frayed or broken cable, or a dangling extension spring, or a dent in the car. In my 30 years servicing garage doors, I have found these symptoms to be some of the more challenging for do-it-yourselfers to diagnose.

Caution: Extension springs can be very dangerous. Replacing the pulleys must be done with the garage door open. Carefully follow all of the safety instructions in this tutorial. Always stay out of the path of extension springs when the garage door is operating or when the door is closed, assuming the cable or spring could break at any moment, and the spring flies off and hits you.

At our parts page, you will find a variety of pulleys you can purchase for your garage door. On this door, 3-inch pulleys equivalent to our PU-30S were replaced with our PU-30H, which is rated to last twice as long. Since all the pulleys in the extension spring system are used approximately the same amount each time the garage door opens and closes, we recommend that you replace all four pulleys - this will save you time and reduce shipping costs.