I have dual Viair 480C compressors mounted in my truck toolbox. When they kick on, the vibration can be heard and felt in the cab of the truck. I know that the compressors have rubber isolating grommets on the mounting feet, but I have been thinking about adding something else to deaden the vibration. What have people used to accomplish this? I was thinking about buying some hockey pucks (which are made of rubber) and drilling a hole in the center, then placing one at each corner of the compressors.
You could try a sound deadener. for instance dynomat, fatmat, peal and seal, second skin etc. I personally havent tried it but im pretty sure that would help.
Bigger rubber mounting feet 
You can get the larger grommets at lowes/HD I forget exactly where they are but they have a couple, and just put them under the pumps rubber grommets and they work wonders!
Iso-mounts are definitely the way to go. They’re about an inch tall and an inch wide with threading in the top, and a bolt coming out the bottom. Run these on top of sound deadening material, as mentioned above, and you’ll seriously reduce the noise.
We used to have three 450Cs running in this manor and it made seemingly less sound than one pump mounted to the frame using the ‘stock’ grommets.
The compressors are mounted to sheetmetal. A sheetmetal installation will always result in noisy vibrational operation. Chassis mounts are always recommended. You’ll need to vibration-isolate your tool box.
Try this first though…
Remove the brass inserts from the vibe isolators and shave 1 mm from each one, and reinstall. Be sure to use nylock nuts and lock washers on each mounting point. to This allows the rubber isolators to compress more and dampen vibrations further.
I know this is an older thread, but I’m looking at a similar mounting on my 08.
So I was wondering what the final solution was; isolators or relocation?
My plan is to mount the compressor and tank to the bottom of the tool box using plywood to beef up the box (on the inside).
Any thoughts?
How bout putting dyno mat down first? Or just get some dense foam / rubber, possiblt something that has some sort of a heat shield to it and put it down… it will absorb sound.
mine are mounted on a 1/8" aluminum plate then the plate is isolated by springs. works well but I need to rebuild the spring holders with a different, more durable material. will post pics when it’s done.
u could always mount the compressors to a piece of wood and have the wood set on top of a piece of 1" Styrofoam or enen a softer foam such as the foam for seat cushions
Isolation
Sounds like a good idea
RTV has less compression resistance than say rubber or other anti-vibrational material. Its best use would be as a sealant, or gasket material.
I stand corrected. From what I understand RTV is silicone?
RTV stands for “room temperature vulcanization” meaning it will solidify at room temperature. Typically, its made of silicone rubber but is best used to make gaskets and such. All RTV I’ve played with hasn’t had the strength to do much as a vibration isolator - unless you used a lot of it and allowed it to set up first. Even then I’m not sure it would work well.
In semi-liquid form, it would just flow out when pressure is applied to it.
I experimented with several different mounting options and materials before settling on the following:
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Use large rubber spacers or grommets under each compressor screw, bolt, or leg. The small rubber grommets included with the Viair units and most other brands help but they are not enough. To make your own spacers just take a solid black rubber bungee cord and cut it into 1" or 2" strips. You can make a few dozen spacers from one strap for less than a dollar and the black EPDM rubber will stand up well to the heat, moisture, and vibration. The Dollar Tree and Big Lots stores sell these straps dirt cheap.
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Mount the compressor to a removable wooden base cut from a 2x6, 2x8, 2x10, or thick 5/8" plywood panel. Use pressure treated wood if it will be exposed to the elements. The wooden platform is cheap and easy to build and it makes it a lot easier to remove, repair, or replace the compressor as needed. It also allows more noise dampening in conjunction with the next item.
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Cover the bottom side of the wooden base with a layer of black foam rubber like the kind which you line toolbox drawers with. You can get a whole roll of this stuff for less than $5 and you can double or triple the layers if the stuff you buy is too thin.
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In most installations such as a trunk or truck bed you won’t need to permanently attach the wooden platform since the weight of the compressor(s), wood, and the non-skid rubber layer on the bottom will keep it in place. If you do need to secure the platform then you should use a few more black rubber bungees. I cut one of the bungee in half and screwed the cut ends to opposite corners of the wooden base. Then the hook ends of the bungees are free to latch on to the truck bed but there is no direct contact between the hard surfaces.
I avoided the use of enclosures because the compressors get very hot and running enclosed makes the heat much worse with a longer cool-down period. They will still run but you will shorten the life span of the compressor. You can install cooling fans in the enclosures but they make their own noise and the fans might fail without your knowledge.
The above solution works pretty well for noise isolation and it is cheap and easy. I also like that I can remove the compressor assembly in less than a minute. When I had a smaller 1-gallon tank I mounted it to the board as well but now I mount my 7-gallon tank separately.
I did notice a significant jump in vibration noise when going from the small single compressor to dual 400C units but the noise is still very reasonable, more like a low and gentle bass rumble, and it can just barely be heard or felt when in the truck cab with the windows up. If the AC or radio is on low then I can’t hear it at all. Definitely acceptable considering that the dual 400C units fill up my 7-gallon tank from empty in about 2 minutes.
My 380c which is mounted in my trunk, directly to floor Vibrates my entire car.
My friend who works in a Lab brought me 4- 1" Rubber Bottle Stoppers w/the hole in the middle.
Just picked u some 2" screws and will install 2night.
James
OK remounted my compressor
same location
still only used 3 screws
installed the 1" rubber stoppers and ALL OF THE VIBRATION IS GONZO.
still noisy, gonna install a foam mat on rear of trunk behind compressor…
I installed my compressor and tank on a 10 ga. steel plate. I mounted the plate to the bottom of my tool box using some rubber belting and hard plastic bushings to provide isolation. Can hardly hear compressor running outside of truck. I can’t hear it at all from inside the cab.
I mounted the horn and SOV inside the left frame rail on a S.S. bracket.
So far, not a single leak. 