The Stovebolt Site Forums The Shop Area Interiors Sound deadening

Has anyone played around with the best approach to reducing the noise in the cab. Specifically placement of the sound deadening matt products. Have you found there are certain areas that seem to have the biggest impact when applying the sound matts or should I just plan on pretty much applying it everywhere? Obviously time and money are factors. If not, just cover everything.

floors?
inside doors?
cab walls?
cab roof?
every possible surface?

What's your goal?

An AD truck is never going to be as quiet inside as a new car. It won't even be as quiet inside as a '65 VW Beetle.

Your windows are likely going to be down when driving in the summer so that negates much of the sound deadening.

I think heat insulation should be your bigger concern which will have sound insulation as a benefit.

Firewall, floor, and ceiling for heat.

Put some HushMat / Dynamat squares on the back of the cab and inside of the doors to dampen vibrations.

Applying to 1/2 to 2/3rds of the inside door skin really quieted down my doors.

I've learned the front cab mount pads in the 3100 will naturally over time settle. The rear ones not so much. I've also learned the replacement pads (which seem to be all made by the same outfit) will settle very quickly...maybe within a few months. If this happens, the front part of the cab will rest right on the mounting spot and that will telegraph lots of noise into the cab. You might think the cab would also be loose as a result, but I haven't found this to be as much of a problem as the noise. You will notice your brake pedal rod may hang in its opening, however. Doesn't take much cab-settling to make this happen. In my experience you need at least 3mm or so of space between the two. Not easy to get an image, but I tried so please look below. How to fix? Go to any hardware store or plumbing supply store and buy some of the material used for shower pan liner. It is a hard but insulating PVC sheet. Then cut rectangles about 2" x 3" and punch or cut with a box cutter a hole for your mounting bolt. Laminate these until you get a height that works for you. Do it for both sides. That stuff won't settle but it will do a good job of insulating against metal to metal transmission of noise (which can be surprisingly loud). If this is a problem for you, solving it should help.

Always felt that the inner door panel was the tinniest and most resonant part of the door assembly, so for the 46 I chose to put the sound deadening on the back side of the door panel not the outer skin, marked out where the braces crossed and fit around them.

It made a huge difference, the doors sound so much heavier/solid when you close them, and no more panel squeeks or rattles
Also did under the floor mat, firewall, and lower cab back behind seat (tank is under seat on 46.)

Didn’t do the roof as headliner is too nice to mess with᠁.

Used SummitRacing branded aluminum/rubber peal & stick kit , “Summit Racingâ„¢ Ultimate Heat Barrier and Sound Deadening Mats”, came as 9 sheets 32”x18”seemed to be a good value.

Chuck

I have a bunch of HushMatt I will start with the floors and inside door panels. I don't expect it to be quiet, just eliminate some of the in a steel drum sound. I see some of the trucks with radios and wonder how you could possibly listen to it.

I did the cab roof, All the floor, gas tank (in cab), rear cab area , both doors from the bottom access panels. It made a night and day difference! I have an original 6 volt AM radio, I can hear it unless I'm going over 45mph, then it's like whispering. Worth your time and money for sure. It keeps the heat in during winter and somewhat keeps the summer heat out.
I used a roofing material (comes in a roll), NO odor.
I got mine at a Lowes. I bought a small hard roller and it was super easy.

Dave I think once you get started you might be surprised. The doors on mine have some of the typical jute/horsehair/tar/linseed oil mat GM used so often attached (not on the door skin but on the inside area). As a boy I got to visit a factory that made that stuff for GM and other automakers. I'm certain this was put there by the factory before the skin was attached. It helps somewhat but there isn't a terrific amount you can do without adding upholstery/padding to the inner side of your doors (which I don't really like). I used foil wrapped fiberglass insulation between the headliner and top (the same stuff HVAC installers use on ductwork) and that's also helpful. Masking tape will hold it in place while you install the headliner. Originally there would have been that jute/horsehair mat I mentioned before, but I had the HVAC stuff from work I had done under the house so I used it. Note: if you do this, run it under the bow that separates the two pieces of fiberboard. On the floor I bought a big piece of 1/8" self-adhesive neoprene sponge and added some thick radiant foil barrier material on top of it using 2 sided adhesive (I could have used spray-on adhesive). You can see some of that in the attached image. Also run it under the seat...it will keep things from rattling under there (things like a jack, lug wrench, etc). For years in the 60s I drove a 1951 GMC half-ton pickup and it was actually fairly quiet. Before I gave it to a friend, I removed the floor mat to clean it well and paint it with tire black and I saw one reason it was more quiet. A previous owner had done what used car salesmen I knew sometimes did. He had taken newspaper made wet with papier-mache solution (seems it was water, flour and salt...maybe it was rice flour) and laminated that all across the floorboard under the mat. When it dried (and around here it doesn't take long), it became a form-fitting thing that resembled an egg carton and I could see he had painted the top with either varnish, varathane or something to give it more strength. It does stop floorboard noise for certain and isn't expensive. Just about anything you do will help. As for the radio, you can listen just fine in my experience unless you're trying to drive too fast. These trucks have serious wind noise problems at highway speed (even really well sealed) and that more than anything will make the radio difficult to hear. In fact having driven these several hundred miles at a time, I would say wind noise is what made those trips more tiring. However in defense of them, I will say nothing has been as tiring as a 300 mile trip I made in an IH Scout around 1966.

I also used Dynamat pretty much any where I could. It really keeps it from sounding like a rattling tin can. Kind of pricey but easy to install. I did inside my doors as much as I could reach. I did a short video on YouTube one with and one without where you can hear the difference closing the doors. I’ll come back and edit to add the link but if you search my name Donald Sessum you should see it.Dynamat doors

I used some rubberized sticky stuff in my doors. With them completely disassembled, there was enough space to get coverage on the whole outer skin. Almost got my arm stuck in there once though.

Yup. That right there. A square in the roof, one on each door, and if your fuel tank isnt in the "smoking position", one on the inside of the back of the cab. Huge difference. Or at least its a huge difference when closing doors or hitting bumps. It takes the "tin" out of the "tin can".

I used dyna mat everywhere I could get my hands. used 1/2 inch closed cell foam on top of that. Replacement firewall pad and carpet with jute padding. Big help was when i used 1/2 inch rubber pads on the front cab mounts and new replacement rear cab mounts from LMC. Their mounts have vulcanized rubber press in bushings. My truck is just as quiet inside as my wifes 2004 Subaru.

I use the harbour freight mat.