Liftmaster 3800 Closing Issues

[nmk_61802]

A while back, I installed a LM3800 opener on one of my two garage doors. This weekend, I installed the second. While testing the second opener I noticed that on this new opener, if the door is opened 24" or less, then stopped and closed, the door will jump up and down on the tracks, and then reverse to full open. This only happens when the door is stopped in the bottom 24" then closed otherwise it work perfectly.

I have set the door pressure, limits, and the cables remain taught. Opener does slow down in the last 12". The door is balanced at the halfway point. The other door I installed previously closes smoothly regaurdless of where it starts from.

I did notice that if I apply pressure on the door while closing in the last 24" it does not bounce and closes smoothly. This indicates to me that I need to take half a turn of the torsion spring to allow give the door slightly more weight while closing to smooth out its operation.

What does eveyone else think?

 

[nmk_61802]

Any thoughts from anyone?

 

[nova65ss]

Trying to undestand what you wrote? Is it just jerky or are you having a problem with it staying down if closed when only part way up?

 

[nmk_61802]

I was hoping that you might respond nova, I know that you have a lot of experience with these. For simplicity sake, let's say the opener is just jerky (kinda bounces up and down on the tracks) when closed from any position other than half open to full open. It works perfectly if I allow it to open completely than close.

The comment about it reversing does happen, but I believe it reverses due to the door bouncing during the last few feet.

 

[nova65ss]

It is likely just the way the tension is on the spring. If it is somewhat strong it will sometimes be jerky because the door is wanting to go up but the opener is pushing it down. It may get better if you take some tension off the spring so it is a little heavy rather than light this way when it starts to close the door is already wanting to close. That make any sense kind of hard to put into words. Unhook the door from the opener and see how it feels is it going up almost by itself or does it want to fall down a few feet from the ground?