How To Shorten a Chamberlain Drive Chain Garage Door Opener
How Shorten the Opener
I measured the door on this job and knew that the door that I put in would fit. So I bought an opener and found out after I tried to put it up that it would not fit in front of the beam. That then required me either buy another one or adapt this one. After inquiring around I found out that they are all standard sizes Length wise. After calling around again I found out that you could adapt the length of this opener with a little work. So here is how.
Hack Saw or Sawzall with a Metal Cutting blade.
Box Wrench Set
Drill Bit Assortment
The first thing you have to know is how much shorter it needs to be to fit in the space that you have. Also there are wires that come out the back that hock up and they need to be accessible for the installation of the Sensor control wires and the plug. You want to leave at least 4’ space in the rear. So holding the opener up measure the amount of space that you need between the back of the unit and the Beam or Heating Duct. In this case I needed 12”. Lower the opener down and put it on a solid surface. Disconnect the chain and cable and remove the bolt from the rail where it connects into the opener. This is where you are going to cut it. Here is the important part. Whatever you cut out of the length you must TAKE THE SAME AMOUNT OFF THE CABLE AND THE CHAIN (from each side).
1. Remove the bolt and cut 12” off the back of the rail. Reinsert it into the opener and drill a hole and reinsert the bolt and nut.
2. Take the cable where it connects into the moving head see Photo B and cut 10” off. The rest is going to make up the loop where you will hook a cable clamp on so it will actually be 12" shorter and tape it with Electrical tape then reattach it.
3. Remove the connector where it connects up to the moving head. Take a grinder and measure 12” and grind off the pins that hold it. Then reconnect the connector to the head.
4. Reinstall the opener and test. You might have to adjust the distant of open or close See Photo A. Adjust the chain tension.