Chamberlain Belt Drive Garage Door Opener Review – Part 2

By |Last updated on |Appliances, Garage|32 Comments

This Chamberlain Belt Drive Garage Door Opener Review is continued from Chamberlain Belt Drive Garage Door Opener Review – Part 1.

Drive Belt Installation

After assembling the rail and trolley, I propped the rail on the garage door strut which was more or less even with the motor head. The drive belt is threaded through the rail and the belt pulley fastened with a bolt. A screw driver is inserted in a hole through the rail to prevent the trolley from moving as the drive belt is attached and tensioned. Note that I have released the outer trolley and moved it to the right out of view.

Chamberlain® Belt Drive Garage Door Opener: Belt and Pulley Installation

A nice feature of the Chamberlain belt drive garage door opener are the slick white plastic wear pads inside the trolley – meaning you never have to lubricate the rail. No oil or grease means there’s nothing to collect dust/dirt and interfere with the trolley movement.

Tighten the Drive Belt

The next steps are:

  • The trolley connector is hooked to the trolley.
    Note that I’ve disengaged the outer trolley and moved it off to the right out of view in the next image.
  • The drive belt is run along the rail and looped around the motor sprocket, then back to the trolley.
  • The threaded rod is attached to the belt connector with a snap-on master link.
  • The spring trolley nut is threaded onto the rod by hand until it is finger tight.

Please refer to the factory installation manual for details.

The only “trick” is to release the spring and snap the nut against the trolley to set the proper belt tension. This is done by holding the nut ring in place with a flat head screw driver and tightening the trolley spring nut about 1/4 turn with a wrench. The spring will release and force the nut ring to the right against the trolley, setting the proper the drive belt tension.

Chamberlain® Belt Drive Garage Door Opener: Belt Attachment and Tightening

Closeup of the trolley spring nut after the spring is released. Chamberlain provides an orange tag illustrating the before and after configurations:

Chamberlain® Belt Drive Garage Door Opener: Trolley Spring Nut

Garage Door Header Bracket

I could have reused the old wall bracket to anchor the rail, but it was a bit off center and higher than necessary, so I removed it and filled in the screw holes with caulk. I centered the Chamberlain bracket a few inches lower on the 2×6 head board while maintain a minimum of 2″ clearance (my actual clearance is about 4″) above the maximum height of the door as it’s raised, drilled 3/16″ pilot holes for the lag screws and fastened the new header bracket to the wall.

Chamberlain® Belt Drive Garage Door Opener: Wall Header Bracket

Hanging the Garage Door Opener

My helper held the motor head while I attached the rail to the header bracket with the included clevis pin. Then I sat the motor head on top of the step ladder. I climbed the step ladder and held the motor head against the ceiling bracket to check center alignment and clearances as the door is manually raised. The ceiling hanging bracket was the correct length, however the motor was about 1″ off center to the right. I moved the bracket arms one hole to the left to center the motor head with the door.

Chamberlain Belt Drive Garage Door Opener: Ceiling Mounting Bracket

The hanging bracket is now centered and the garage door opener attached with included hex bolts. The ceiling bracket only carries the weight of the motor head and rail.

Chamberlain® Belt Drive Garage Door Opener: Ceiling Bracket Mount

Closeup of the trolley, header bracket and emergency release rope:

Chamberlain Belt Drive Garage Door Opener: Trolley and Header Bracket

Sectional Garage Door Reinforcement Bracket

Section garage doors require a reinforcement bracket distribute the load of the door bracket.

The prior homeowner (a goober) failed to grasp this necessity and botched the job by fastening the old door bracket directly to the door with two hex screws, a pan head sheet metal screw, and of all things – a drywall screw! He apparently never wondered why the door bracket was wider than the door rib.

Garage Door Opener Bracket: Incorrect Installation

The absence of a door reinforcement bracket caused the door rib to bulge outward somewhat because it was not designed to take the door opener load in a concentrated spot. The top hex screw was carrying most of the stress and raised a 3/16″ nub in the door rib as it tried to pull out.

Clopay® Garage Door Opener Reinforcement Bracket

Chamberlain recommends checking with your garage door manufacturer for a door reinforcement kit. I purchased a Clopay 21″ Reinforcement Bracket (a.k.a. “Opener Reinforcement Bracket”) that fit my sectional garage door perfectly. The top section of my door is 21″ high which matches the length of the 21″ Clopay Reinforcement Bracket. See the Clopay bracket installation instructions for details.

I removed the old garage door bracket and am ready to install the new Clopay 21″ reinforcement bracket. The Clopay bracket is well made, very rigid and provides for direct attachment of the door arm. The kit includes a matching clevis and cotter pin.

Clopay 21 in. Garage Door Operator Reinforcement Bracket Installation

The Clopay reinforcement bracket slides under the top door strut and fits over the the hinge leaf. I removed the four hex screws from the strut and hinge leaf to fit the bracket on the door:

Clopay Garage Door Reinforcement Bracket Installation Details

The Clopay bracket has generous pre-formed holes to remount the hex screws in the existing holes. The exception was the off center hole in the horizontal strut for which I drilled a 3/16″ in pilot hole through the Clopay door bracket to match.

Clopay Garage Door Reinforcement Bracket Installation: Hex Screw Fasteners

The installed Clopay reinforcement bracket. What an improvement!

Clopay Garage Door Operator Reinforcement Bracket Installation

Minor item: I broke the head off the 1/4″ hex screw in the top strut, so I drilled a new 3/16″ pilot hole in the door strut and Clopay bracket to set a new screw.

The Chamberlain belt drive door arm is attached to the built-in Clopay door bracket using the provided clevis pin and cotter pin:

Clopay Garage Door Operator Reinforcement Bracket: Door Arm Attachment

This review is concluded in Chamberlain Belt Drive Garage Door Opener Review – Part 3.

Thanks for reading,

Bob Jackson

Copyright © 2019   Reproduction strictly prohibited.


  1. Alan August 12, 2013 at 12:42 am - Reply

    I was assembling my new garage door opener and and the instructions that came with the opener show a different spring trolley nut assembly than what came with my new opener.
    Just found YOUR instructions above and they do a much better job than what I found on the Chamberlain website.
    Thanks for posting this

  2. Bob September 3, 2013 at 10:16 pm - Reply

    I am installing new Chamberlain WD962KEV Ultimate Whisper Drive garage door opener. Both the Chamberlain instructions shipped with the drive, and the instructions at the Chamberlain web site show a different belt tensioner than what is included with the currently shipping garage door opener. Your instructions describe the currently shipping belt tensioner. Thank you. I also appreciate the information about the Clopay garage door reinforcement bracket and have just purchased it through Amazon. Thanks for what you do…

  3. glen October 12, 2013 at 8:47 pm - Reply

    The spring assembly instructions didn’t make any sense with the parts I had, Chamberlain change the specs on the spring assembly but not the instructions, your one picture/instructions made a big difference thanks for the help!

  4. Bob November 9, 2013 at 7:02 pm - Reply

    I had the same manual issue showing the wrong spring. What I would like to know is where did your manual come from and when? Your manual shows a drawing that matches your spring. So at one time the two did in fact match one another. Sounds like they changed the spring and the manuals are current but they are sill shipping the old spring.

  5. toby February 2, 2014 at 2:07 am - Reply

    I’m so happy to have found this page! It helped me tremendously with the spring trolly installation. I had it all wrong! With your pictures and addendum link I was able to install it correctly, and now the belt tension is correct. While I have a craftsman opener, it’s identical to the chamberlain. The instruction manual that came with the opener was not updated. Shame on Sears!

  6. Brian May 15, 2014 at 9:22 pm - Reply

    I just finished installing a Chamberlain belt Drive – my first belt drive garage door opener. As it was opening, I noticed the belt would ride up on the trolley as the trolley made it’s way to the motor. I was wondering if this was ok or if there was a way to adjust it. The door opens perfectly, but I suspect after a while that belt will wear more and more as it slides up on the trolley.

    • Bob Jackson May 15, 2014 at 9:53 pm - Reply

      Is the belt sagging and riding onto the trolley? It shouldn’t do that. Try tightening the belt to take out the slack.

      • Brian May 16, 2014 at 11:55 am - Reply

        It looks like on that side of the trolley there’s a curved piece that sticks out and it looks pretty tight. But I’ll tighten it up slightly and see if it changes it. The belt doesn’t sag at all.

        • JJ July 3, 2016 at 7:27 pm - Reply

          Brian I have the same issue my belt touches the outside of the trolley. Infact the trolley has a little rubber sleeve over the metal, so im not sure if its supposed to rub?

          how did yours work out?

  7. Howard September 17, 2014 at 12:11 pm - Reply

    Thanks for the clear instructions. Your web site is better than the factory’s manual.

  8. Bob Lamberson December 18, 2014 at 12:01 pm - Reply

    garage door opener hangs up and does not want to come down. have checked the connections and they seem tight. no obstructions to the sensors. can the sensors become dirty and if so how to clean them? thanks

    • Bob Jackson December 18, 2014 at 6:21 pm - Reply

      Do you have any error codes? The garage door opener lights will flash an error code sequence and it will be displayed on the Smart Control Panel LCD if a fault is detected.

      Have you tried adjusting the downward force and lubricating the door tracks? Grease thickens in cold weather and the metal tracks tend to shrink somewhat which increases friction.


  9. wendell March 12, 2015 at 11:07 am - Reply

    Just installed my 3/4 Chamberlain whisper. I too have a belt that rides under the trolly when opening. And sags quite a bit. I guess I should try tightening the belt?

    • Bob Jackson March 12, 2015 at 10:25 pm - Reply

      The belt will sag a little, maybe an inch or so, but it shouldn’t sag so much it whips around and/or droops several inches. Yes, try tightening it.

  10. Jon April 7, 2015 at 9:56 pm - Reply

    So I just finished my install and had the same question as Brian above. The belt seems tight but it does ride against the trolly which makes the door jiggle a bit as it opens and closes. Not a huge deal but I’d like to know if it’s not supposed to do that. Thanks!

    • Bob Jackson April 12, 2015 at 9:55 am - Reply

      Hi Jon,
      The belt may bump (gently) against the left side of the outer trolley as the door opens & closes. “Left side” here is standing at the garage door entrance looking at the motor unit. Notice the outer trolley is flared on the left side forming a bumper guard.

      When the door operates the rail will flex under load especially when the door panels make that 90 degree turn in the door tracks. The flexing rail will momentarily cause a minor amount of sag in the drive belt, which will tend to swing sideways and bump the left side of the outer trolley. The drive belt on my door never rises above or below the outer trolley bumper which is an indicator the belt is sufficiently tensioned. Belt wear hasn’t been an issue.


  11. Ron Petty October 25, 2015 at 10:08 pm - Reply

    Hi Bob
    I installed my first 3/4 horse chamberlain belt drive system on a standard two car garage door. Im
    noticing a little deflection on the trolley rail when door is closing but seems to work smooth, is this normal
    I do not see anything miss aligned or binding.

    thanks ,Ron

    • Bob Jackson October 26, 2015 at 1:02 am - Reply

      It’s normal for the rail to flex a bit but not so much the belt sags and whips around.

  12. Shawn November 1, 2015 at 10:20 am - Reply

    Hi Bob, the belt on my Chamberlain belt drive hang a bit below the T rail on one side only when the door is closed. The belt appears to align correctly when the door is open/opening. Should the belt be tightened?

  13. Ed February 9, 2017 at 4:18 pm - Reply

    I had this same opener installed a year ago. I’m not 100% sure but it seems like the door is opening slower now. Have you notice that with your unit?

    • Bob Jackson February 9, 2017 at 5:35 pm - Reply

      My opener is now 4 years old and works fine. Check if the rails need cleaning and lubrication. Grease can thicken in cold weather, garage door lubricant spray is best.

      It could be caused by lower than normal AC supply voltage. Use a digital volt meter to read the voltage at the ceiling outlet. It should be 110 to 120 volts AC.

  14. Gary February 24, 2017 at 6:05 pm - Reply

    To change the wear pads do I have to take the trolley assembly right off the rail

  15. Gary February 24, 2017 at 7:25 pm - Reply

    I bought the pads for 4.00$ I tried to just pop the only 2 that were left and slide in the 4 new ones with no luck. It’s too tight not enough slack. So I guess I am gonna just have to take it apart

  16. Mickey McAllister April 24, 2017 at 4:25 pm - Reply

    I just replaced the belt on my Chamberlain garbage door and now it will close but it opens on its on, but it goes up a foot and stop. When can I do to correct this. Mickey

    • Bob Jackson April 24, 2017 at 6:01 pm - Reply

      The opening force on newer Chamberlain doors is automatic and cannot be adjusted. Per the user manual:

      “The electronic controls sense the amount of force required to open and close the door. The force is adjusted automatically when you program the travel.”

      Close the door and disconnect the trolley by pulling down on the red plastic handle attached to the rope. Also notice the two heavy black a href=”” target=”_blank”>torsion spring in the photo at the previous link.

      Now open the door manually with one hand. The door should open easily because it’s balanced by the heavy torsion spring(s). If the door feels very heavy then the torsion spring(s) may be broken or possibly have worked loose. Also see How to test the balance of a garage door.

      My door has two springs while some doors have a single spring. A broken spring is easy to identify and in my experience they break every 5 years or so with frequent use. If you happen to be in the garage when a spring breaks it sounds like a rifle shot. Call a repair company like Overhead Door (they replaced my springs) because the spring is under great tension and dangerous.

  17. paul December 16, 2018 at 8:48 am - Reply

    just installed a 1/2 hp belt drive system. first can Chamberlain print their instructions a littler bigger, the second is a bigger problem. someone was talking to me as I set the up adjustment and it hit the stop bolt, got a code but when I went to reverse the trolley nothing. the belt was so tight on the pull side but loses on the return side.
    I fixed it by removing the belt is there a way to release motor tension with out removing the belt?

    • Bob Jackson December 16, 2018 at 1:53 pm - Reply

      Loosing the spring trolley nut should release the belt tension.

Leave A Comment