When it comes to installing liftmaster chamberlain and craftsman garage door openers there are three different ways to install them the first is the most simple and easiest installation process and that is lift masters 3800 series of jack shaft wall mount openers.
The reason for this simplicity in installation is that these garage door openers do not have a rail system they are mounted on the wall at the upper left or upper right hand side of your garage door they are engineered to attach directly to the torsion pull and do not have a rail system or any chains or belts or screws to attach to the opener in order for it to operate so therefore the only process with the 3800 series is to mounted on the wall and then run your safety sensor wires and that is pretty much it except for force and limit adjustments and remote programing. The other two processes for installing standard garage door openers are the following if you have purchased any liftmaster or chamberlain product at a retail hardware store then they come with what is known as a 5-piece rail system they use this 5-piece rail system so that they can fit the whole rail into the box that the opener comes in. The other rail system that openers come from the manufacturer with is a professional grade opener which you can only buy at a garage door supply warehouse and is made for professionals only and the difference is the rail for these types of openers whether it is chain belt or screw drive will come in a nine foot long square box and the whole rail system is already assembled and the rail is all one solid piece and there is no assembling of the rail for the chain and belt or screw rail. The most common types of openers with a 5-piece rail assembly are usually any opener that has chamberlain on the box or craftsman or power drive brands will all usually use a five piece rail assembly system and if the opener says liftmaster on the box it is most likely comes with a one piece solid t- rail. So when it comes to the five piece rail system that you have to assemble yourself with a do it yourself opener kit then here are a few pointers that you probably will not find in the instructions. The first thing you should know is that when you are assembling the rail and you have all the rail pieces together in the right place then you will have to bend the metal tabs on each piece of the rail 5 in total and when you have to bend these tabs in you should use a hammer and a center punch if you do not have a center punch then a sturdy very short screwdriver will do just fine. The main thing that you want to be sure of is that when you are assembling derail you are doing it on a level flat surface like the concrete floor in your garage if you try to do it on a curved driveway or even on your lawn then the whale can have some slight curves or bends in it from not being on a level surface when the tabs. Also do not forget that there are tabs on both sides of the rail do not forget to do both sides.
5-piece rail system
Also on a 5-piece rail system dont forget to slide the trolley on the rail before you start to assemble the chain or belt because you will have to take a few things off if you forget to put the trolley on the rail at the right time. Also the trolley will need to be at the front of the rail do not slide it halfway on or all the way towards the motor head because it will cause all kinds of problems and you will have to reset that trolley where it is at the front this is because the first time that you activate the opener it is going to open first not close. Also if you are assembling a chain or belt drive opener put the chain or belt through the slot in the front of the opener well before you attach the pulley because if you try to squeeze it in after it usually does not fit. These are just a few things that I can think of that you should be careful of when you are assembling a do-it-yourself garage door opener. Now if you are assembling a solid trail that most the garage door companies use then it is as simple as mounting the rail to the opener head and tightening down the chain or belt to specs and a screw drive rail system is even easier because there is no chain or belt to tighten. If you are going to install an opener yourself then I would try to stay away from screw drive openers they are a little bit more difficult to assemble. Now there is one more dilemma that may came up when you are installing a opener yourself some garages have a support beam that is anywhere from 829 feet back from the garage door opening and if you go to hang the opener and it does not fit in that 8-9 foot area and when you lift up the motor head to mount the opener to the ceiling and the motor head hits that beam and does not fit then you will have to shorten the rail to make it fit inside that bean but you can not shorten it too much or the garage door will not open all the way I do not suggest that you try to do this unless you are very mechanically inclined and good with power tools.
Already assembled the opener unit? Here is what u need to do the easiest way to prevent this problem after you have already assembled the opener unit you should attach the anchor bracket at the front of the open a real and get a tape measure and measure exactly from the front anchor bracket all the way to the very back of the motor head and once you get that measurement write it down and then you should measure the area from the header above your garage door, you will mount the front of the opener all the way back to the support mean and if your measurement is shorter than the full length of the opener and rail then it is probably not going to fit so what you will need to do is figure out what the difference in the measurements are and once you have that number that is how much you will need to cut off of the opener rail. You should never try to shorten the opener rail by cutting off the amount you need from the front of the rail where it mounts to the wall above your garage door this will not work and you will have to start all over and probably purchase a new rail. You should always trim off the excess rail in the back where it mounts to the motor head. I have never tried to shorten an open door rail with anything but a belt drive opener because it is far too difficult to shorten a chain or screw drive rail. To avoid any of this hassle it might be a good idea to determine whether you have a support beam in your garage and it is close to the back of the garage door track. If you know that you are going to have to shorten the opener rail before you even purchase an opener unit at a retail hardware store this will save you a huge amount of hassle. The reason that I used belt drive openers to shorten and open the unit is because when you shorten the rail you must also shorten the belt or else it will not work unless you are shortening the rail only an inch or two. And even then you could still have a problem because the belt might not tighten up all the way like it should be. These are just a few things you should think about before you tackle installing an opener yourself.