(Please note: I’m not a structural engineer or even a licensed contractor. If you decide to do this modification, it is at your own risk.)
UPDATE: I found a much simpler approach
Our garage door opener motor was LOUD! The whole room above it vibrated far more loudly than being in the garage with the motor. This is due to the mechanical connection of the motor to rigid metal straps which are then bolted to the ceiling beam.
I spent a few weeks studying how other people and companies try to solve this issue. Some methods would probably work but appeared kind of dangerous (such as hanging the motor housing from rubber straps). The point of vibration isolation is to have an insert of some kind that will absorb the energy of the vibration without transmitting it to the beams and walls of the house. Most solutions seem to use rubber or Sorbothane pads to sandwich the metal frame, with the idea that the two pads will jiggle and absorb the energy of the vibrating metal.
KEY IDEA: A rigid structure will always transmit the vibrational energy; a flexible insert before the ceiling will absorb the vibrational energy and transmit far less.
I looked at using rubber or Sorbothane washers between the metal and the ceiling, but in order to seat the lag bolts properly, I would have to squish the washers which would drastically reduce the vibration-absorbing ability of the material (it needs to be able to jiggle to absorb the energy). I thought about bolting rubber pads above and below the metal straping to help absorb the vibrations. But the stiffness of the pads which would directly touch the ceiling and the bolting seemed counter-intuitive to me (it just didn’t seem like it would work).
I looked at all kinds of vibration absorbing pads and other vibration isolators, but finally settled on a hanging neoprene isolator (Mason 2LVR8). They do make spring versions, but those are really made for large heavy motors instead of a lightweight garage door opener. I needed something that would easily jiggle, and these neoprene isolators were rated at 0-30 pounds, which sounded perfect. I also chose to add neoprene washers as an additional damper on 2 spots where loose metal was going to touch. I bought the Mason isolators online from a vendor named Grainger for $9 each. Amazon actually wanted $6 more per unit! I used three isolators to hold the motor. That may be overkill for the light weight, but I wanted three anchor points on the ceiling like the original installation.
NOTE: The center track for the garage door is fairly level to begin with. This means that after I installed the isolators, the motor had to move up a few holes in the metal strap. That was easier than cutting the strap metal.
To mount the isolators, I used “hanger bolts” to replace the lag bolts that originally held the metal straps to the ceiling. Hanger bolts don’t have a head. Instead, they have a wood screw side for anchoring to wood beams, and a machine screw side to accept nuts. In order to drive them into the ceiling (into the existing holes from the current lag bolts), I used the two-nut method (a jam nut and a regular nut tightened together). I used 5/16 inch bolts because that is what was currently installed in the ceiling beam. The current lag bolts were 2 inches long, so I used 3 inch long hanger bolts to leave some bolt hanging down from the ceiling. See the pic below.
They do make a special driver made just for the purpose of installing hanger bolts, but such a driver only works to install, not to remove, so it has a very limited purpose. It is difficult to remove a hanger bolt but the two-nut method is usually used for that also. The next picture shows the whole thing installed. I used a nylon locking nut on the top of the isolator housing (shown on the bolt pic above), and another nylon locking nut and washer to hold the housing rigidly tight to the ceiling. The purpose of the top nut was the regulate how much of the hanger bolt was allowed inside the housing. As you can see below, there isn’t much room for the top and bottom bolts to coexist without touching, but they must not touch. I ended up with about a 1/4 inch gap between the two bolts. You can see the gap between the ceiling and the two other units in the pic below.
KEY IDEA: The concept of the hanging isolator is to put vibrations from a hanging device into the jiggly and squishy neoprene. The jiggling action uses up the energy and keeps it from being directly transmitted to the rigid metal above it. If the bottom bolt were tight against the bottom of the unit, a lot more energy would be transferred to the housing and then to the ceiling beam and that would defeat the purpose of the isolator.
I set a ladder and a box underneath the motor to keep it from sagging very far while I worked on the straps. The weight of the opener motor and track was apx 20-25lbs. I used another ladder to move around and work. This picture shows the installed isolators with the ladder under the motor unit. I had to have an additional box to keep the track from sagging and possibly bending.
The next picture shows the order of assembly of the top pieces:
(DO NOT assemble this way prior to install. It all has to be installed piece by piece on the ceiling. This is just to show how it is all assembled.)
1. hanger bolt
2. nylon locking nut (need pliers to hold wood screw part while installing nut)
3. isolator housing
4. metal washer (optional)
5. nylon locking nut
6. lower bolt
7. nylon locking nut
8. neoprene washer
9. 5/16 metal “fender” washer
10. the neoprene isolator (built into the housing)
11. neoprene washer at head of lower bolt
Any place where I was going to have loose metal touching metal, I put in a neoprene washer to absorb energy that would otherwise become a rattling sound.There is about a 1/4 inch gap between the ends of the bolts. Plenty for the amount of jiggling of this motor.
Mason 2LVR8 from Grainger.com $9 x7 ($63)
Hanger bolts x3
Machine bolts x3 (I chose 2 1/2 inch)
standard 5/16 metal washers x3
5/16 fender washers x3
3/8 (fit better) neoprene washers x6
5/16 nylon locking nuts x9
(I estimate the various little parts cost around $12)
adjustable wrench, ratcheting crescent wrench, vise grips or pliers, impact driver and impact sockets, ear protection when using impact driver
The impact driver is handy for installing the hanger bolts. It is very quick, but does make a racket. The nice part is that there is no torque on the handle like there is with a standard drill motor. But a wrench or a socket driver can insert the hanger bolts also, it just takes longer.
I remounted the motor to the metal straps and used a level on the center track to verify that I had it pretty close to level.
I measured the sound before and after the install using both a Realistic brand sound pressure meter, and an Android app called Spectrum Analyzer. Unfortunately, I forgot to squish the range of the Spectrum Analyzer to show the range of human hearing (~1KH to 4KHz), so I only got the default low end.
Overall it shows about a 20dB drop. The other sound meter before registered about 66dB in the room above the opener. After the isolator install there wasn’t enough noise to even move the meter (range was about 60-80). There is an odd constant peak at about 130 Hz. Not sure what that is.
In human reaction terms that is “WOW! The noise is almost totally gone!” Originally, I was going to install these on the door tracks also, and install pads where the tracks attach to the garage wall. But after the decrease in noise, that became unnecessary.
This project is likely beyond the ability of many homeowners, but could be installed by a contractor easily. It did take several hours because I was still working out the details as I was going.
I don’t think that there will be any issue with the motor not having a rigid mount. It seems to operate normally and with very little visible jiggling except when it first starts or when it is about to finish.
I also did this fix at another house, but felt that it would also benefit from having the door raceways muffled a bit more. Sadly, I didn’t take any sound readings on this before starting the project.
I used Sorbothane bushings and washers, since I already had some. The object here is to float the perforated metal between the jiggly material. The top part is like a washer, but has a middle insert. I had to drill out the hole in the metal to 1/2 inch first so that the insert would fit. Then I used a lag bolt that is 1/2 inch longer than was originally installed, so that I could get the same grip while leaving a bit of slack so the metal could vibrate without being tightly pressed against the beam (the white area at the top of the picture). This should help absorb a bit more of the vibration without transferring it directly through the metal parts to the beam. I may leave a bit more slack than is shown in the picture. If the material is too squished, then it loses its ability to jiggle and becomes pointless. I used a washer under the material to help hold it in place. Sorbothane is easily torn by metal edges or screws.
But now that we are selling the house, I’m going to remove the isolators and reinstall the lag screws. If anything were to go wrong with the unit, the blame would be on me regardless of whether or not that blame were real, and I can’t afford that. But that gives me more isolators to use in my other house where we have two garage door openers.