Wall Mount Garage Door Opener - Question for Current Users

[BoylermanCT]

I am looking to install a Chamberlain wall mount garage door opener in my barn. I have two 9x9 sectional metal overhead doors. I am sold on the advantages of the wall mount unit, extra head room, quiet drive etc. but I don't understand how it makes the door close. To open, the drive rotates the door's main shaft which wraps the door cable around the spool and lifts the door up. As my door is installed now, once up, you have to tug gently on the pull rope to get it to come down. The main spring is tensioned so the door stays put half way up. Above half way and the spring wants to pull the door up and below half way the spring wants to let the door close. So if the opener reverses direction and turns the drive shaft the opposite way of opening, why won't the cable simply unwind off the drum? My door is on standard tracks where the door is lying parallel to the floor when fully open. I don't see my door wanting to close unless I completely change the tension of the spring so it is trying to pull down when fully opened which would seem to make the motor work really hard to open the door.

I read through the Chamberlain installation manual and watched their installation videos, but did not see anything to address this. Maybe I am missing something. If anyone has one, can you help me understand how the closing process works so the door starts moving down vs simply unwinding the cable. I figured I would start with the TBN crowd before sitting on hold trying to reach Chamberlain.

 

[s219]

I have two LiftMaster 8500 units now, and had one at our previous house. I installed all of them.

If you've ever set the torsion springs on these doors, you know that they are pretty sensitive once you get into the ballpark of proper balance. Add just a little more tension and the door wants to go up on it's own. Take away a little tension and the door will drop on it's own. For closing, all a jackshat opener does is to counteract a teeny bit of the spring torsional tension so that gravity can take over. It's just like if you yourself had taken 1/2 turn off the spring tension. The doors are heavy enough that they don't need much help.

I think you can answer your own question in a convincing matter by putting a pipe wrench on the end of your jackshaft and give it a turn. You'll see the door go down and the cables stay tight. Your muscles are doing what the opener's motor would do, offsetting just a little bit of the spring torsional tension.

 

[s219]

By the way, your door and track should not be fully horizontal up top -- there should be a slight slope to the track, and furthermore, the very bottom section of the door should be in the corner of the track and still have some amount of angle. Usually the bottom of the door and bottom wheels sit slightly below the opening header (so you should see about 3-6" of door hanging down into the opening). If the door is going up much past that point or is completely up on the upper section of the track, then you should adjust the stops and maybe re-check the spring tension.

From what you described the spring is set right. Should take light effort to lift the door to about halfway, then the spring should provide gentle counterbalance and help lift the rest of the way but not any sort of acceleration or pull. The door should run into final position gently and not jerk the cables too far past vertical. If the door pulls hard to the stops and/or the cables are being pulled towards horizontal then the door is going too far and/or the springs have too much tension.

 

[Citydude]

You can install these.

Garage Door Plunger Bumper Spring, 15" - Tools Products - Amazon.com

Garage Door Plunger Bumper Spring, 15" - Tools Products - Amazon.com

www.amazon.com

 

[workinonit]

I have 2 8500 LiftMaster on 2 - 12 x 10 roll up doors on my shop. I love them. I'm thinking about putting a roll up on my garage.

 

[not2old]

I didn't have enough head room to have sufficient slope on the door in the horizontal position to guarantee it closes properly. I installed the springs shown post #4 and think things will be OK. I haven't installed the operator yet. When I do intall it, I will check out how it works with the pipe wrench method suggested in post #2. Be sure to adjust things so that the cable doesn't just unspool as the whole door will come crashing down. It could range from serious injury to killing someone.

 

[BoylermanCT]

Thanks S219. The door rails go up two feet above the top of the door opening, so the bottom door panel is still almost vertical and the next panel is at a 45 degree angle and the other 4 panels are on the flat section.

I went out with a pipe wrench and turned the shaft by hand, and the door came down without loosening the cables. I never would have guessed. I may end up raising the rail ends so the horizontal track is not perfectly level. Thanks for your help!

I'm ordering the 8500 openers after Christmas.

 

[dstig1]

I just put 2 of them in (8500's). You might need to back off the springs by 1/4-1/2 turn, but you can certainly give it a try first and see if it works or not. If the cable goes slack then you will need to reduce tension slightly, but your test with the pipe wrench may have already answered that. There is a cable tension monitor and getting it set right is probably the hardest part of the install. I had to shim behind mine with some thin plywood scraps to set the distance from the wall right.

 

[MHarryE]

My Liftmaster 8500 stopped this winter - 11 years. I think the door rollers are getting tired and the door won’t slide down the slope like it did new. One hesitation resulted in an hour straightening cables. So now I have a pair of down assists to install on the track ends. Another option would be to add more tilt as I have the room but I opted for the assists.

 

[310-510]

Thanks MHarryE. I did not think of down assists. Every time the cables came off I would add slope to the tracks, adjust spring tension and limit the opening height. It only happened in the beginning when setting up the doors.
4 Liftmaster/Chamberlain 8500 on 12x14 sectional doors.

I will order the down assists (plunger bumper springs) now and reset the doors to open the full height.
carl