Sound Deadening Material Question

There is also a brand called Fatmat. Similar to to dynamat but not supposed to stink. Never used it.
www.fatmat.com/

 

Can you show me in greater detail how to do this? "My" columbia is loud as hell.

 

Oh man, sound damping is a classic problem. Truck/car companies spend lots trying to do a good job at a reasonable cost and weight. Big trucks make a lot of low frequency noises (<90Hz), which are difficult to absorb.
I can't give you exact details for your truck because I am not familiar with it, but I can give some basic rules to follow.
First, the noise in the cab has four sources.
1. Outside noise transmitted into the cab via hard surfaces. Windows, firewall, floorboards, etc. This noise is reduced by changing the mass/dampening ratio of the item. That is heavy carpeting, mats, rubber mounts, thick flexible seals to stop windows from transmitting.

2. Outside noise that enters via open spaces. Gaps in door and window seals, clutch linkages through floorboard. Seal the gaps, but be careful, don't provide a vibration path from one part to another. Soft, flexible seals.

3. Noise created inside the cab from parts hitting each other. Loose items rattling around, loose panels, hard surface to hard surface contact. Again soft flexible seals to prevent rubbing.

4. Noise inside reflected by hard flat surfaces inside the cab. Bare floorboards, cabinet walls. Cover any hard flat surface with something rough and flexible. Carpet, leather(with a thin pad under it), heavy thick cloth, etc.

The traditional way, and the most reliable methods involve shear mass. Heavy, soft. flexible materials, like 'leaded vinyls', rubber, etc. work very well.

There are newer, hi-tech ways, but it requires a lot of data and analysis to work.

But we don't want to add a lot of weight. I mean it would be easy if you don't mind 300 lbs extra, or maybe a little more.
For Number 1
Concentrate the thick heavy padding on the firewall (and engine cover if Cab Over) and cover as much as you can, even if you have use some thinner stuff in some areas.
Glue this in place if possible. Use a glue that stays soft and pliable and is easy to remove. Do the same on the floorboards, though you might use a thinner lighter material than on the firewall. A good pad and carpet should be enough. Again, glue it down, or at least the pad to the carpet. Velcro can be used if you like.
Also, you can buy spray on dampening (undercoat) and use where you see fit, but a lot of guys don't like it. Think of as permanent.

For number 2
Seal all openings. Simple rubber grommets for holes. Make sure the door and window seals are in good shape. Heavy tape can be used to cover small holes, cracks, etc. Use a metal foil tape. Check the windshield seals, make sure the glass is touching only seals or sealant (it would crack if it wasn't).

For Number 3
Check every panel, bolted on item, access panel, etc. Dash panels are frequent cause of rattles. Glove box door, fuse panel, etc. Little rubber pads, silicone 'caulk'. Put the silicone where you want it, cover with plastic wrap and put the panel back on. When it dries, you can peel the plastic wrap off and have a perfectly fitted seal.

Number 4
Cover every hard smooth surface you can with something soft and textured. Yeah, somethings need to be hard and smooth, so you can't do all of them.

As to which products to use, I will say this. For the heavy sound dampening mats buy the one that offers the most weight per $, at least 3/8" thk. Note: some of these mats come with a smooth side and a rough side. The smooth side contacts the panel, the rough side faces into the cab (yeah, it is important). The carpeting is up to you, but for noise purposes, the thicker, softer, and heavier the better. The tape, rubber seals, grommets, silicone sealant (caulk) are all standard hardware store or auto supply store stuff.

Really don't need to spend a lot of money, but it will take some time and work. You don't have to do it all at once. Concentrate on items 1 and 2 first.

Obviously, I have rambled enough. The engineer in me escapes once in a while and this is interesting subject!!!

 

http://www.quietride.com/catalogpdfs/peterbilt_truck_catalog.pdf

prefab kits seem kind of high$$$ but i havnt found any cheap sound insulation

 

I have used roofing tar (blackjack), on my pick up floors, yeah it smelled, but helped. Friend recommended the Kool Seal elastomeric (rubberized) roof coatings designed for metal roof mobile homes.
http://www.koolseal.com/product_family.asp?family=elastomeric
Very durable coating, reasonably priced (approx. $15/gal. at local home improvement store.), water based, easy clean up, dries in about 30 min. I have used it on other projects, but not for sound control. Hoping to coat the floor (in cab, and under side) on my W9 next slow spell. I also bought some 1" neoprene sponge to put on the underside of the floor after I "Kool Seal" it.

 

I have been into car stereo's most of my life and I can tell you from experance dynamat is the best out there yeah it does cost a bit more and heavy but its well worth it, but my only thing is using it in a rig would that add extra weight and still be legal at 80,000lbs? oh and the spray on stuff its ok but its MESSY!!!!

 

www.secondskinaudio.com

Good stuff. Good information. Never used any personally, theirs or others, but my research shows them to have a solid product and great knowledge.

http://forum.sounddomain.com/ubbthreads.php?ubb=showflat&Number=882568&page=1#Post882568

http://forum.sounddomain.com/ubbthreads.php?ubb=showflat&Number=1487187&page

Also check out those links. I have been a mod on that forum for a while and know that there is a TON of helpful people on there. As far as I know, that first link directs you to the only really scientific review of sound deadening materials.

 

Any one try spray on lizzard skin ceramic coating ?

 

Great info, thanks all, been researching this sound stuff for a while, now I can stop thinking LOL yippy, thanks again