Cummins600

With most of my driving at 75 mph I'm attempting to reduce the sound level in the cab. It would be nice to hear a cleaner stereo at this speed. I've already sprayed about 5 cans of rubberized undercoating under the cab and that helped some. Will soon be installing 50 sq. ft. of Dynamat type (really B-Quiet Ultimate) deadener material in the cab. Any recommendations on the best and most impactful place to start installing to reduce hi-way speed noise (tires, wind, tranny, muffler, etc.)?

I'll be conducting my own test on the effectiveness of this project also. A new professional sound decibel meter is on its way to me so I can record sound levels before & after install. Planning to test at the same speed, on the same road surface, and near the same ambient temps. I really want to see how many decibels are reduced from my efforts.

Don't get me wrong, I love the sound of the Cummins, but want my quiet time on the hi-way in the cab.

BigBlue

The back wall of the cab lets in a lot of noise. I put one layer of dynamat on there and it quited the cab down a lot. Then the doors and floor. Firewall.

IA_James

There was a thread on this on TDR, the guy had done a load of work trying to quiet his truck down. Wound up getting called the "Noise ****" or something. Had alot of info on silencing these things.

mishkaya

Check out these two threads, they will answer most of your questions:
http://www.turbodieselregister.com/f...ound+deadening
http://www.turbodieselregister.com/f...ound+deadening
Mishkaya

BarryG

When I did mine here is what I did.
I put a layer of bquiet and or dynomat extreme on the inside of the outer door skin, the inside of the inner door skin and the outside of the inner door skin. I did that on the front doors and the qc doors. I also put as much as I could in the space behind the rear door and the back wall in the corner. I put 3 layers on the back wall. The back wall behind the seat has no insulation it is just bare tin. I put two layers under the carpet behind the front seats. That is where I ran out of material. Up to that point I used one 36sf box of dynomat extreme and one 50sf roll of bquiet brownbread. I still have about 8sf of dyno extreme left but Iwasnt going to tear out the front interior just to put that in. I have since ordered another roll of the bquiet ultimate sitting in the garage just waiting for it to warm up to finish the job. I also put some in the cowl area under the hood in the fresh air intake. That thing is a cave. I put in as much as I could reach in there. So I have done everything except the roof which I am not going to do and the front half of the floor on up the firewall. There was a definite difference I do not have db meter so I could not take any measurements to verify the difference but you can sure hear it. Cant wait to finish up the job.

I did not check out the above mentioned threads but if they are the ones I am thinking of they are informative.

The bquiet ultimate is certainly cheaper than the dynomat extreme and though the specs are very close to each other the dynomat extreme seemed to be of higher quality. I suggest that you do it when it is warm I had my stuff laid out on the driveway in the sun and it sure made it easy to get it to conform to the contours easy.

Good luck, you will hear a difference and it will definitely be better but dont expect the noise level of a lexus.

Cummins600

Thanks for the links and info. Sounds like 50 sq. ft. can be used-up pretty fast depending on the layer amount. I'll use the db meter to try and locate the main source areas for higher sound levels and tackle those places first. Apparently, the doors and rear wall will get the highest readings.

Cummins600

Man, after busting my butt to install 50 sq. ft. of sound deadener I'm not so sure. Did it over three installs so the effect may not be so striking. Overall, the ride cab noise is a bit more muffled - even things like road bumps. although, my main focus installing was 65+ mph cab noise and that didn't seem to change too much. My install focus was the front doors and rear cab wall & under rear seats (what a blast to install). I was really hoping for better results after that amount of time spent. I'll re-use my decibel meter when the weather conditions are about the same as my first test to really see what happened.

Lightman

Cummins600, if you like go to TDR and view my reader's rigs - under LightmanE300. I have pics of all the dynamat xtreme I installed. I used 72 sq feet just doing the floor under the rear seats, the rear wall, and the doors. The improvement was significant! Hopefully you have good luck with the b-quiet stuff, but I know people that have had problems with its adhesion once temps get hot. The glue would start melting and the stuff would move/come off.

I dont see any reason to use imitation or knockoff dynamat when you can get a 36sq foot bulk pack of xtreme for $89 on ebay.. These are $250 in the store.

As far as your noise reduction results, how much did you put in? Did you cover every bit of paneling in the areas you did, and make sure they were well rolled?

I got three full sheets (12 sq feet) in each door, doing a SINGLE layer If you hit them from the outside with your fist you get a serious dead/vibration free thud, compared to the hollow/tinny noise of the stock doors. This helped a lot.

Another area where a majority of the sound is coming through is the headliner/roof. I still have to do the floor below the front seats as well as the headliner. As you have found Cummins600, it's VERY VERY labor intensive. Not difficult, just time consuming.

Does your thumb hurt yet from using the roller?

Cummins600

Lightman, I have seen your photos and your install work should be the example to follow. It looks like dynamat art! I covered the front doors very well with one layer inside and out. Also did the rear wall w/one layer and two in some spots. The rear floor under the seats and feet area got one layer (covered about 85%). Used my 50sq. ft. roll of b-quiet (http://www.b-quiet.com/brownbread.html) Utlimate. Which seems to be a good quality product (pretty good eye for that stuff). It cost $100.00 (shipped) for 50sq. ft. Also, I read-up on the product and found it to be very well received by many. My research told me that this stuff is very close to dynamat (some say better and others don't).

So, today I drive my normal 85 mile drive and got a better idea of the improvements made. My main goal (like yours) was to reduce the hi-way speed noise, but that was minimal, but better and improved. Slower speeds have really improved and the stereo is clearer now. Things like being in a cement parking garage (w/rebound motor noise) are much quieter and trucks to your side down hi-ways are better. Not sure I'm going to invest any more time and money into this type of project.

Decibel meter compression to follow.

Shovelhead

Nice work.

Here's a couple of pictures of Lightman's work from his TDR gallery:



Before:
http://www.turbodieselregister.com/u...d=9455&width=0

After:
http://www.turbodieselregister.com/u...d=9461&width=0

Cummins600

Look, no ear muffs in use here......dynamat must be installed!

http://www.turbodieselregister.com/u...d=9465&width=0

Lightman

I just hate to leave a job half finished. One of these days I'll do the rest of the floor under the front seats and the headliner. I really think a good deal of the wind noise is coming in thru the headliner. I'm not sure how hard it is to remove or not.

Thanks for the compliments on the dynamatting - it took forever!

Cummins600

Yep, that hi-way speed noise from wind, tires, motor, headliner, exhaust, etc seem to come in through all parts of the truck. The whole thing kind of turns into a tuning fork of sorts. My decibel readings would pretty much read the same in open space, but get the tool closer to any parts (window, floors, doors, dash) and the reading would increase by about 2-3 db's, but be consistent again. It is a real time suck and by back is slightly jack-up too now. Good thing I have some fun while doing these type of projects.

Cummins600

Here are the results from my meter test after the install. Basically, the sound level from the drivers seat area was reduced by one decibel. Idle, 65 mph and 70 mph test all reduced by one db with fairly controlled conditions. Apparently one db makes a difference because it is noticeably quieter. Even some passengers claim to notice a slight change in sound levels.

Idel: 50db to 49db
65mph: 65db to 64db
70mph: 68db to 67db

DSLRammin

200 sqft later, 3 layers, Stereo sounds better, better for highway noise, only a little better for the drone from a 5" exhaust




2 layers in all doors.