Over head door specialist

[Buzzards]

Will a liftmaster jackshaft opener # 8500 have enough jam for a clopay 18x12 -2" thick over head door. I feel the door is too big and heavy. Thanks buzzard

 

[rslaback]

If the door is properly balanced it shouldn't take any extra force due to the size of the door, right? The opener replaces you, not the springs.

 

[rburke65]

What does your door weigh and what is the weight limts for the opener? The spec of the jack shaft is available and you can weigh your door. But as stated, thespringtakes carrot most of it.

 

[DeliveryGuy]

I've been told by Liftmaster reps that the limiting factor in how large of a door the 3800/8500 can lift is the length of the cable tension monitor. On a door with very large cable drums, the cable tension monitor may not be long enough when the cable spools back and forth on the drum.

18x12 is quite large. There's still a lot of inertia, even if the door is well balanced. There's 12ft of rubber weatherstrip on each side for the machine to fight, in each direction. The manual says a maximum of 180 square feet, and your door is 216sq/ft. I would recommend a Liftmaster MH5011, medium duty commercial unit. They are a bit more expensive, but easier to install.

 

[AndyL]

No...

Says right in the manual 180sqft maximum - 18x12 is 216.

But, that said - ive seen them move bigger and heavier. But its really not correct and 0 warranty if you go that route.

 

[Buzzards]

18x12 is quite large. There's still a lot of inertia, even if the door is well balanced. There's 12ft of rubber weatherstrip on each side for the machine to fight, in each direction. The manual says a maximum of 180 square feet, and your door is 216sq/ft. I would recommend a Liftmaster MH5011, medium duty commercial unit. They are a bit more expensive, but easier to install.[/QUOTE]

THANKS FOR ALL THE REPLYS, I AM THINKING THE EXACTLY THE SAME THING AS DELIVERY GUY

 

[GroverDill]

I was told by liftmaster that the weight of the door is more of the limiting factor ( 650 lbs max) if its under 14' tall. I was given the green light for my insulated 16x12

 

[DeliveryGuy]

A 16x12 door could very well have 4" diameter cable drums, or 5.25" drums, compatible with the cable tension monitor. A 9x7 with 6ft of high-lift will have massive cone shaped drums which will require a lot more torque to turn, even with a smaller door. Not to mention, they are like 8 inches deep. Way too long for the tension monitor.

P.S, I've found that the electric solenoid lock that comes with the 3800/8500 is too short to work effectively with some 3" commercial track and rollers. In some cases, the roller can shimmy by the engaged lock if there's too much play in the rollers.