Sound proofing

[Jelmer]

Now that our 93 goes into hibernation for the winter it is a good time to get the truck a bit more quiet.
What have you guys done to make it more quiet on the freeway? In Holland the normal freeway speed is 80-85mph so pretty fast which causes a lot of noise.
A lot of noise comes from the doors, rhs under the dash and from the gear boot.

[Philip]

I used Lizard skin on the floors. I then went over that with Dynamat. I also did the roof and inside of the doors with Dynamat. I had the dash out at the time so the firewall was also done.

The biggest improvements are the floor and the doors. Our doors let a lot of sound it. The firewall has enough supporst welded into it. There isn't much noise from it.

The floor shifter lets in a lot of sound. My truck used to be an auto. When I converted it to stick. I noticed the extra noise from the shifter.

[meby]

I used dynamat extreme on the roof, floor, doors... basically anything resembling a flat surface. The doors I also gave a thin layer of dynaliner. Two layers of jute insulation on the floor with a third over the hump.

Presently the truck is within 2 decibels of dad's 05 Cummins at 60 mph.

[Richie O]

Where and how do you do the doors? Where does the material go?

[PToombs]

Where and how do you do the doors? Where does the material go?

You just peel the backing and stick it to the outside of the door. The noise comes from outside, so that's where you need it the most.

[meby]

Where and how do you do the doors? Where does the material go?

before I reassembled the doors, I put strips of dynamat extreme on the outer shell and then right before I put on the inside panel, I covered each door under the panel area with an entire sheet of dynamat extreme. Plus I put some thin 1/8" soundproofing on the back side of the panel itself.

[Richie O]

before I reassembled the doors, I put strips of dynamat extreme on the outer shell and then right before I put on the inside panel, I covered each door under the panel area with an entire sheet of dynamat extreme. Plus I put some thin 1/8" soundproofing on the back side of the panel itself.

Ok, I thought that would be a pain to have all the layers between the panel and the door.


And to Pete, as always your a great help, you pinhead

[PToombs]

Well, I figured it was kinda common sense to put it on the door skin.

[meby]

before I reassembled the doors, I put strips of dynamat extreme on the outer shell and then right before I put on the inside panel, I covered each door under the panel area with an entire sheet of dynamat extreme. Plus I put some thin 1/8" soundproofing on the back side of the panel itself.

Ok, I thought that would be a pain to have all the layers between the panel and the door.

If I ever have to get back inside the door, it will be a bit of a pain. Until then, I figured one solid sheet should help cut noise a lot.

[Philip]

Hea Matt Give me some DB numbers on your truck.

Base number just setting in the truck not running. My number was 60

Truck idling setting. Mine was 90.

Running 60 MPH in OD cruise set no radio. Mine was 94

[Jelmer]

Thanks guys! Looks like Dynamat is the stuff to get!

[meby]

Hea Matt Give me some DB numbers on your truck.

Base number just setting in the truck not running. My number was 60

Truck idling setting. Mine was 90.

Running 60 MPH in OD cruise set no radio. Mine was 94

It's been eight months since we tested...I think mine was 70 db after. No before numbers. Don't hold me to that though, a lot of things have run through my brain since. If I get a chance, I'll look it up tonight.

[meby]

70 db was right. 55 db idling.

[Pausma]

When I soundproofed my cab I removed the seat and carpet. The product I used was called fat mat, similar to dynamat but a little cheaper. I put fat mat as far up the firewall as I could without pulling the dash apart. I then applied fat mat on the entire floor and all the way up the back of the cab to the rear window. Made a huge difference mostly with engine noise and vibrations in the cab.

At highway speeds the wind noise is still pretty loud. I have some fat mat left and I plan to put it inside the doors.

Another area to look at is the quality of your door and window seals. I know the triangle windows are a leaky spot on first gens. I plan to do door seals on my truck and see if it helps and if I get ambitious enough I may replace the window seals as well but I know those can be a real pain.

[Jelmer]

It is indeed noisy at the door seals and window seals. We replaced both already (OEM Dodge) but the window seals are not keeping the window thight. You can wiggle it front and back and you feel the wind coming in when driving. I'm thinking about putting some foam like stuff behind the window seals so that the window sit thighter in them.