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How to replace garage door opener

Man replacing garage door opener

Many homeowners have decided at some point in time in order to save some money they would buy and replace their garage door opener. If you are handy and have the tools readily available it can indeed save you some money and is not a terrible idea if you can find an opener on sale at a really good price. 


However, many customers have called us after starting the project for help finishing. Others have completed the project in the past and when it comes time to either a) replace it again or b) do the other side and vowed to never do it again, so they call us. 


This guide will try to cover what is involved so you can decide if this is a project you really want to take on. This is not intended to take the place of an instructional manual.


Before we begin though, it’s important to note that different manufacturers have different size nuts and bolts that they use, making the tools needed a little different depending on the garage door opener that you buy. 


Tools you will need:


We have attempted to compile a list of all possible tools no matter what brand you have bought or are taking down. 


  •  ¼” Drive Impact driver
  • 7/16”  Deep well socket
  • ½” Deep Well Socket
  • 9/16” Deep well socket
  • 7/16” Magnetic socket with a 3” – 6” extension
  • ⅜” Magnetic socket with a 3”- 6” extension
  • ½” Wrench
  • ⅝” Wrench 
  • Philips head screwdriver
  • Flathead screwdriver
  • Wire strippers
  • Step stool
  • 6ft ladder
  • Saw horse
  • Table



First things first, go ahead and pull everything out of the box and lay all the parts out on your table. It is going to be helpful to have things organized and ready to go. Check your contents in the box to what the instruction manual says should be in the box. It is not common but sometimes you might be missing a part and it is better to know now rather than later. 


Step 1 : Unplug the old opener and disconnect the wires from the back. I recommend looping the wall button wires so you can tell them apart later.


Step 2


Assemble your rail. If you bought your opener from a hardware store no matter what brand you will need to assemble the rail most are just made of square tubing that slide into each other and lock in place. 


Step 3:


Attach the rail to the head unit. This is where your sawhorse will come in handy. Keep the head unit on the table and rest the other end of the rail on the sawhorse. This will prevent you from kneeling down and bending over, saving your back and knees. 


Step 4:


Attach the trolley to the rail. This is done on most openers by simply sliding the trolley onto the rail. Make sure that it is facing the correct direction. For example: on a chamberlain opener the lever for the emergency release should be pointing towards the door. 


Step 5:


Run your belt or chain through the end of the rail where your idler pulley will go, and attach it to the trolley. 


Pro Tip: stick a phillips head screwdriver in a hole in the rail to keep the trolley from sliding off when you attach the chain or belt. 


Step 6: 


Attach the idler pulley. Make sure to use the proper nuts and bolts and that they are nice and tight. Do not just attach this piece any old way. 


Step 7:


Wrap your chain or belt around the idler pulley and the sprocket on the motor head and connect it to the other end of your trolley, and tighten the belt or chain so it falls right in the middle of your rail. 


Step 8: 


Install the wall button. On Chamberlain, Craftsman or LiftMaster remember polarity matters when connecting the wires. If you are screwing your wall station to drywall be sure to use the anchors supplied.


Step 9 :


Install the new sensors, yes you need to remove the old ones and put the new ones on. Again for the above mentioned brands polarity matters so pay attention and make sure theyare connected correctly.


Step 10:


Install keypad if applicable. 


Step 11:


Remove your old opener. 


Set up a 6 ft ladder underneath your old opener and step stool near the door under the opener rail. Disconnect the old opener from the wall, and rest it on the door. Remove the old mounting bracket and install the new one. Go to the 6 ft ladder and remove the bolts holding it to the backhang.Slowly carry it down and set it on the ground. 


Step 12:


Hang your New Opener


Prop your rail up to the header bracket, with the head unit resting on the ground. Climb your step stool and insert the cotter pin, and secure it. Grab the head unit and walk up the ladder. Holding the opener from the bottom, connect the first bolt and finger tighten the nut and then do the same for the other side. Then tighten the bolts with your impact. 


Lastly plug your opener in and connect your wires and program your limit and force settings according to your owners manual. 

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