how does the Jackshaft 3800 GDO work?

[Mn_Z_Man]

OK, this sounds like a stupid obvious question, but I can't get my head around it. I would like to install a Liftmaster 3800 GDO because I have a 4-post lift. I was going to fabricate (jerry rig) a bracket and modify my conventional GDO to work on the jackshaft, but talked my self out of it when I started reading up on the 3800. I can get one for $250 (self installed). The installation manual calls for a well balanced GD that stays put when lifted 1/2 way. If it is balanced, how does it move down???? Gravity has to be the only force, which means it would HAVE to be adjusted so it would close and stay closed- am I missing something? I just don't want to get it in and have it not work, and have to pay an installer anyway!

Thanks

Eric

 

[tdkkart]

The installation manual calls for a well balanced GD that stays put when lifted 1/2 way. If it is balanced, how does it move down???? Gravity has to be the only force, which means it would HAVE to be adjusted so it would close and stay closed- am I missing something? I just don't want to get it in and have it not work, and have to pay an installer anyway!Eric

"Balanced" WITH the springs and cables attached, so the spring and cables are actually holding the door in it's neutral position. As soon as the 3800 rotates the jackshaft in the downward direction the door is no longer "balanced" and will roll down under it's own weight.
Other than that, the 3800 works very well. I have 4 of them, pleased every time I hit the button.

 

[Mn_Z_Man]

thanks, I knew I was missing something! that makes perfect sense when you put it that way-

Eric

 

[Spudland_Dave]

IF your doors arent setup perfectly...you'll hate the 3800's.... And by perfectly I mean "Perfectly Specifically for a 3800" all my doors are brand new and as smooth as silk/glass when using them by hand, but for a stretch a few weeks ago I was about to chuck all 3 LM3800's in the garbage (one is still in the box)...think i've adjusted my tracks to the point where things are good...been fine since...But I still have this little pit in my stomach whenever I press the button to make the door go down..gonna be a while before I have complete faith in them.

I will not and can not blame LM for this...nor the opener itself, Just one of them things where this style of opener, while a VERY good one, requires things to be setup a little differently. The old fashioned normal openers will open up & close with amazing relialibilty even the shoddiest installed of doors.

 

[my58]

I see that others have had problems and you need to take that into account. I will also say I have 1 and love it. It is quiet, smooth and I love the sound of the click when it latches.

I highly recommend them. Just 1 of many opinions.

Good luck with whatever you choose.

 

[larry4406]

I have 4. Three installed by the company that installed the doors, the 4th by me on an existing door that had a prior belt drive unit. All work great.

 

[BudgetRacing]

As the owner of a door company and a Liftmaster dealer i guess i should provide some information. I have read a few threads on here about people dealing with problems with their 3800/3900's. There are 2 main issues people have when installing these units. Number one is the slope on the horizontal tracks is not enough to overcome the initial start up which will throw the cables off or hopefully trip the cable sensor if it is properly installed. The second reason i have found is even if the door runs smoothly without binding/catching is that the rollers may be worn or damaged which will not be noticeable as you move the door by hand but there is very little weight on the cables when the door is in the fully open position. Fixing these two problems usually solves 99% of all issues with jack-shaft operator install.

Do not adjust the spring tension, it will not change anything. Do not try to put pusher springs as this will also not help.

 

[kvom]

I installed two on my 10x10 shop doors. Love them. Doors were new and professionally installed, and I have had zero issues in 4 years.

 

[Mn_Z_Man]

thanks for all the tips. what is this about the slope of the tracks- mine are horizontal, checked with a level- can you buy the "elbow piece" with something other than a 90 deg bend? I've never heard of that.

thanks again

Eric

 

[Bakerman]

Have two, will never buy anything else. Smooth as silk, perfectly reliable, the ONLY solution for a lift bay!

 

[DonnyT]

Not to hijack this thread, but which torsion springs are you guys using?? Standard?? EZ-Set?? Wayne Dalton Tourque Master ???

 

[Mn_Z_Man]

let someone answer my question about the slope of of the tracks, then you can hijack my thread- and just out of curiosity, why did you say "not to hijack the thread..", and then hijack it?

 

[DonnyT]

My apoligies, didn't think it would be a problem really. Just looking for info as you. Happy New year my friend.

 

[KPSquared]

I'm not sure I undetstand how to "add slope" either. Do you just lift the horizontal tracks at one end and create a gap where the bend meets the vertical track?

How much slope? I currently have about 2" over 10'.

 

[pattenp]

thanks for all the tips. what is this about the slope of the tracks- mine are horizontal, checked with a level- can you buy the "elbow piece" with something other than a 90 deg bend? I've never heard of that.

thanks again

Eric

I have the LM3800 on a standard track set-up door and my horizontals have 1" slope in 8' and there is a slight gap where the tracks connect at the turn.. The bottom door panel is at the radius turn when open so there is the weight of that panel to start pulling the door close. I also have a LM3800 on a highlift door and the horizontals are flat because the bottom two door panels are still vertical and provide weight to start the door to close, so no slope of the horizontal tracks is needed.

 

[Mn_Z_Man]

Got it on the slope- so if I do need it, just just fudge it, no special connector needed. And no biggie on the hijack, just a wry observation on my part, have a happy new year, I'm heading out to the garage now to mess with the snow blower.

E

 

[BudgetRacing]

No, the small gap is usually not a problem unless you have VERY worn rollers or cheap nylon rollers (the kind with no bearings). You should be able to loosen the two 1/4" nuts (7/16" wrench) and lift the back of the track up a hole or 2 in the punched angle. Usually 1 hole is one inch. I like to do 2 usually.

To answer your question about springs, i find the best springs are the normal torsion springs but the ones from Clopay. They are galvanized which stops you from having to lube them for the sake of not rusting.

 

[Chris05gto]

I have a 3800 that I installed myself,( for my Bendpak HD-9) I bought one for my son and I paid 100.00 to have it installed. When my Craftsman over head opener on my other door dies I will buy another 3800.
Good luck!

 

[Spudland_Dave]

No, the small gap is usually not a problem unless you have VERY worn rollers or cheap nylon rollers (the kind with no bearings). You should be able to loosen the two 1/4" nuts (7/16" wrench) and lift the back of the track up a hole or 2 in the punched angle. Usually 1 hole is one inch. I like to do 2 usually.

After "tuning" 2 of my 3 doors (3rd one this weekend maybe) the gap varies from track to track I'm finding...one of my tracks is super perfect, another one has a 1/8" gap, and another has a 1/8" gap on the opposite side of the other. All tracks were purchased together, all strapped together by Wayne Dalton...so I'd say accuracy in the tracks wont be a problem. IMO The production tolerances for them are "close enough"
If your worried about it (or **** about it) you could take a few minutes with a 4.5" grinder with a flap wheel like I did...massage them so they are pretty much perfect or at least less gap.

After having an issue with the one door I'm using all the time, I bumped up the track 2" (2 holes) at the rear..didnt really find it made any difference, so I went full bore and lifted em 10" more. Now I can see the door & opener works much better in terms of when the opener starts working, the door instantly responds. Still gonna take me a while before I can learn to "trust the opener/door" again but I am still liking the 3800's.

 

[BudgetRacing]

After having an issue with the one door I'm using all the time, I bumped up the track 2" (2 holes) at the rear..didnt really find it made any difference, so I went full bore and lifted em 10" more. Now I can see the door & opener works much better in terms of when the opener starts working, the door instantly responds. Still gonna take me a while before I can learn to "trust the opener/door" again but I am still liking the 3800's.

Ya if it was not even level when it was installed then you will need to go extreme. This is also the case when the door is either very light or the rollers aren't perfect. It really is a good unit that take gets a lot of bad reviews because the doors aren't up to par.

 

[2001RedCoupeBandit]

Love my 2 that just were installed last week on a single and double garage door. I got these for a new bendPak lift, but now like them better anyway even if I didn't have the lift.

On one fo them, the 2 door heavier garage door, when the door closes there is still about a 1/8" GAP at the bottom of the door when its all the way down.

After the door is closed with the 1/8" Gap, I can physically push the garage door all the way so it is totally sealed and closed. with just 1 finger I adjusted the open/close positions and the Downforce adjustments. Can't figure it out, the single door closes fine!


Any Ideas? I am thinking the Garage Door Spring needs to have a Little More downward force. What do you guys think?


I will post pics of my set up soon. They look so damn good! Just love the entire look of the opener and the HIGH LIFT Conversion.

 

[JakeKohl]

I had to play with my spring tension on my 16' door to prevent the 3800 from kicking out from too much load when opening - but I still had no problem precisely setting the end point. Because the opener is removing spring force from the door to move it down, I don't think spring tension is your problem.

In your situation, I would probably look to see if something is slipping (drive connection or cable pulley) you shouldn't be able to push the door further down after the opener has stopped. You might have a second person look over the attachment while you push it down that final distance to see what's moving.