As most of you know, the Freightliners are rather noisy, so as a PhD in acoustics, you know it has driven me nuts. I have a new acoustics manufacture that does vehicle dampening as well. If anyone is interested, I will log the progress as well as the good and the bad. So far all I have done is take the interior out of the cab. The dash is next. I am installing three different types of acoustic dampeners.
1) sound barrier on the floor and fire wall
2) vibration dampeners on the doors
3) sound absorption inside of the dash

I'll post some pictures if it all works. My company does acoustic control for buildings, so this is kind of new to me.

Doc Weaver

Souns Dyn-O-Mat!
oops I mean Dyn-O-Mite!

if you roll on dyno-mat, just wash all the steel down real good with soap and water, then a quick wipe with rubbing alcohol, and the surface is reay to roll on the dynomat. you should use a small 1" roller to press it into all the grooves and corners. We put 2 layers on the floor of my GMC 6500. and 1 layer on the door panels. it took 2 guys 4-5 hours to roll it all down.
https://www.truckconversion.net/attac...0b0c314d67.jpg

According to the numbers, the products I am using have almost twice the dampening power of Dynamat. Dynamat is, for the most part, a vibration dampener. I am using three different types of product from the same company. This company has been used on the Trick My Truck show.

This is the first time I have used this company, but from the discussions I have had with the head designers, they know acoustics and they know their product. We shall soon see.

Doc Weaver

Sounds cool to me. I put a nice am/fm/cd player in my cab. Then I wired in two headphone jacks. I wear some nice Sony headphones with the leather/foam earcups that are good about sealing against my fat head and sealing out cab noise. Works great for listening to MPR while cruising. I've got tinted side windows in the cab and I sit back in the seat. So, if I spot a cop car I think I can rip the headphones off before they can spot me wearing them. And, I don't wear them around town, just on the highway where I'm mostly sitting in the right lane anyhow, except when passing other campers that is, hahaaahahah.

I've got one door done. The heat gun is paramount. This stuff is fairly sturdy, but when heat is applied, it softens right up. Instead of butylene, it is made of strange vinyl. The idea is that once it cools to the shape of the door, it is stronger and controls any vibration. It is a good concept. Testing will be after the rest is complete.

Doc Weaver

Doc,
Please tell us the name of the company you are using.

I have some experience with "Sound-Down" on a previous RV insulating the dog house. They are mostly "Boat People" but did a good job coaching me on that project.

Rad

The company is CAE. I contacted them for commercial, but they do car, truck, home theater, and boats too.

The driver door is done, and now I have the dash apart. I'm starting to understand how all of these products are supposed to work. Their theory is sound (forgive the pun). It should work well.

Doc Weaver

I've got the acoustic control installed. The first impression is a 12 db drop on the highway. The road noise and wind noise are greatly reduced. The engine noise is still leaking through a few places. I'm looking into fixes for them. Overall I am pleased with results. We no longer need to yell while on the highway.

I tried to post pics, but it didn't take. If I can get the pics up, I will explain what we did.

Doc Weaver

I found a loud spot between the door and the side of the dash. Apparently the door doesn't seal very well. I put weather stripping on the door, but I haven't had time to test yet.

The other thing I found was a hollow body piece of the body that fits between the side of the hood and the door. It seems to catch motor noise and funnel it to the front door jamb (the same place that I put weather stripping). I'm looking into foam bagging that piece of the body.

ideas are welcome.

Doc Weaver

By foam bagging do you mean expansive iceynene spray foam? If it is a hollow cavity, iceynene would work well, G

Yes, but you put a plastic bag in the cavity first and spray the foam inside the bag. This way, if you ever have to do any body work, you unbolt the piece and take the foam out. it's kinda flammable and sticky.

Doc Weaver

I test the truck after the weather stripping on the door, and everything came together. I am hovering about 70db on the highway. That is a lot more comfortable than before. Its funny, I turned on the radio and thought it sounded so loud. I can hear it so much better. I had to turn it down.

All in all, I spent about $500 and a little labor. driving to Louisiana next week will be vastly less stressful.

Doc Weaver

Doc
Any chance of more pictures? I would like to know what products you used and where. Also any installation hints on those products.
Thanks in advance.

i haven't figured out how to post pics yet. I will figure it out soon.

Doc Weaver

I have a facebook account where I post all the pics. Then you can link to them anywhere else and everybody can view them. If you're not on facebook you're being left behind by this new generation. Plus, I've re-connected with a bunch of olde friends from high school because of facebook.

Oh yeah, I check Facebook with my email. It is rather addicting. I'll look into that when I get back from Louisiana.

Doc Weaver

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Great pictures. Looks cool. Looks like a lot of work tho. I'd like to do this to my truck, but I'd probably not be able to get things back together.

Bob, my front room in the truck was full of cab parts for three days. https://www.truckhome.com/infopop/emo...icon_smile.gif

I'm still hunting down noises. I'm afraid the windshield is letting most of the noise in. The sound proofing is only as good as the weakest link. I'm contemplating making a cowl cover to redirect some sound over the cab.

Speaking of which, anyone have a good place to find a used roof fairing?

Doc Weaver

Doc
Have you made your cowl cover yet?
Where are you going to place it?
What did you do in the dash by the gauges and warning lights?
What exact products did you use and where?
Do you have any more pictures of this sound project?

Thanks in advance,
Marty

RaceItAgain,
1)I have not had time to even think about the cowl idea yet.
2) I cut and stuffed a fireproof treated cotton panel in the dash anywhere I could (including by the gauges)
3)The products are from one of brands I sell called CAE. I used VB2HD on the doors and VB4 on the firewall and floor. The cotton panel comes from them too.
4) I'll see if there is any other pictures that I didn't post already.

Doc Weaver

Thanks for the additional info Doc.
Please keep us informed about this ongoing project.

Hi Doc.......Thanks for the pics and information on your sound reduction project. I have a Freightliner M2 and am just about to start on the interior with the hopes of making it more comfortable and quiet. Do you sell the products that you used? I'd like to keep things "in the family" so to speak.

I do. I try not to push myself in any forum, but I do appreciate "keeping in the family". If you want to email me at doc@christianmanagement.com I can help you (outside of the forum).

Doc Weaver

well I did a little more to quieten down the Freightshaker.

1) the noise from the tranny seemed be as loud as the engine, so I gave it another look. The hole for the gear shifter was letting lots of noise through the floor. I took three pieces of sound barrier and pushed them down the gear shifter. the bottom one was big enough to put under the boot bracket. The hole has to be big enough for the shifter to move. the second one was the size of the inside of the boot. the top one was to make a tight fit over the movement hole.

2) I changed the tranny oil to Royal Purple synthetic. It is supposed to have a thicker gear film (the stuff that clings to the gears) so that the gears actually never touch. Acoustically that would decouple the sound and keep it from traveling from gear to gear. It would also protect the gears more.

I don't know how much each one helped, but it absolutely make a difference. The sound level is 5 to 10 db quieter. Little by little its getting better.

Doc Weaver

.....OR IS YOUR HEARING GOING LIKE MINE IS.....HUH!..(.YOU KNOW WHO)....................

On the subject of gear shift noise, I quieted down my 7.3L Ford quite a bit with 2 or 3 layers of Reflectix (available at Home Depot/Lowes and others I'm sure) under the boot and the "carpet" -- incredible noise difference! As a matter of fact I noticed on the first drive after replacing the tranny that my hydraulics guy hadn't replaced the stuff... put more down and immediately could hold conversation in the truck again.

It's number 3 on the list of all-time most important items (duct tape and WD-40 being the first 2) for if you're too hot or its too noisy, add Reflectix!

It looks a bit like tinfoil bubblewrap. Used it extensively in the GMC motorhome while mobile and stationary to control heat and noise to very good results, as well.