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Sweet Lew 12-16-2011 08:20 PM

Garage door chain sag

My garage door chain was starting to sag so I tightened it per the LiftMaster manual: center of chain sags so it's 1/2" above the base of the T. So I did that. However, the other side (non adjustment side) of the chain is a little higher. Does this matter? Also, do you really need to disengage the trolley before adjusting the chain?



DexterII 12-17-2011 05:20 AM

Always refer to your manual, but yes, typically you would disengage the trolley before adjusting the chain, and with that done, you should be able to gently press down on whicever side of the chain that is high, and see that the sag is the same on both sides. Disengaging the trolley is as simple as pulling down on the release lever, and re-engaging it is as simple as flipping the lever back to the horizontal position. There is a generally a hole in this lever, through which you can attach a short piece of rope, in order to disengage and re-engage the trolley, from the floor, in the event that you need to manually raise or lower the door during a power outage. As long as it is fresh, now is also a good time to ensure that the door springs are properly adjusted. With the door disengaged from the opener, you should be able to raise and lower the door with minimal effort, and it should remain fully open or fully closed on its' own. If not, contact a local door opener company to adjust your springs.

firehawkmph 12-17-2011 12:09 PM

along with what Dexter said, if you don't disconnect the trolley, some of that sag can be caused by tension on the steel track. Depending on where the lower limit control is sent, the tension on the track can be substantial. It is ok to have a little bit of tension, but it shouldn't be so great that it starts flexing your track noticeably.
Also, the other part of checking your door for proper spring tension is to raise it up about halfway. It should stop and stay there without falling back to the ground, or raising all the way up. It's called the balance point. You will have to stop the door manually to do this. Don't just give it a heave from the down position and let it go.
Mike Hawkins:)

Sweet Lew 12-17-2011 01:07 PM

Thanks for your replies!

I will re-adjust the chain with the trolley disengaged. One last question. Does it matter is the door is up or down? The manual doesn't say anything except to ALWAYS disengage the trolley when adjusting the chain. I just had the springs replaced last winter, so that's been taken care of. I've had to disengage the trolley this summer and the door lifted effortlessly.



DexterII 12-17-2011 02:21 PM

With the trolley disengaged, the door is a completely separate and remote entity, so no, it does not matter, except that I always do it with the door down, for two reasons. First of all, it is out of the way, so that you can see what you are doing better, and second, but most important, when disconnected from the trolley the door is free to proceed down on its' own, so if you happen to bump it, and the springs are not properly adjusted, it can continue down with enough force to severely injure someone, or worse.

Sweet Lew 12-19-2011 08:48 AM

Thanks again! Everything is good to go. :thumbsup:

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