Craftsman 3/4 HP Garage Door Opener w/Extension

brian_nbOctober 26, 2009

I just installed a 9.18450 opener with a track extension for my 8 foot X 16 foot insulated steel door.

I was able to get the auto-reverse function working with a 2X4 in the door's path. The sensors work with an obstruction - preventing the door from moving.

The problem I have is the door will not open all the way. For example, it does open to about 6 feet and I have adjusted the uplift setting to maximum but it doesn't make any difference. I was wondering if I need to do something else to get the motor to lift this taller door.


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Chris Spinnato

When you installed the opener with the 8ft rail, did you use the new chain and cable that came with the extension kit? If you used the existing chain and cable it is only good for a 7 ft door, that is possibly why the door only opens about 6 ft. You need to use the chain and cable that comes with the extension kit. to fully open the door.

    Bookmark   October 26, 2009 at 6:56PM
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The longer rail for the eight foot door eats up another foot of chain, so only opening to six feet makes sense, if the original chain was used.

    Bookmark   October 27, 2009 at 9:15AM
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If he bought a track extension and installed it, that moves the motor unit back a foot to accomodate the 8 foot high door. The original chain would not fit and would be impossible to install.
I think what most likely happened here is you had the carriage assembly in the wrong position on the T rail when you installed the chain around the sprocket. (timeing is off)

Run the motor unit until the door opens to it's fullest height. Now, loosen off chain so you can slip the chain OFF the sprocket. Using just your hands, pull the chain to move the carriage assembly back towards the motor unit until the door is in the fully open position. Now put the chain around the sprocket and tighten it up.
Now, the door is in the fully open position, and the motor unit "thinks" it is in the fully open position.
Push the button and let the door close as far as it will close. From that point, you will have to adjust your "down" limit switch appropriately.
Let us know how you make out.

    Bookmark   October 27, 2009 at 11:06PM
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Is it ok to install a 8ft belt drive Marantec 380 synergy garage door opener on a 7ft garage door?

    Bookmark   16 hours ago
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