47-55.1 Sound barriers / Interior insulation

[e015475]

Here's what I did to address the points Russ made in his write-up

"knowing that, seal the direct paths: holes in the firewall, floor, doors and door jambs, anywhere that air can leak in."


Every panel that was removable, like the transmission cover and battery cover, I sealed with a gasket made from 3/16" closed cell foam. I used the Steele Rubber products on the doors and used the 'dollar bill' test to make sure there was contact everywhere. I run stock pedals so I found some rubber gators to replace the factory felt seals. For the steering column firewall penetration, I used Dumdum on the interior side and a boot on the firewall side to seal it. I found a Dodge shift boot and a substantial chrome trim ring that I mounted to the floor with nutserts so I could pull it down for a good seal.

..... adding mass (usually asphalt) to a panel lowers its frequency, and lower frequencies are much harder to reproduce and need a lot more power.

You can do it cheap with the foil-lined asphalt stuff from Home Depot, but it stinks (literally, especially in the Arizona heat). Killmat is about the cheapest alternative and that's what I used (Made in Russia - kinda strange) I had 100% coverage on the floor, underneath the seat, as far up the firewall as I could get it and the back of the cab, and on the roof. For the doors, I only covered about 40% of the door skin. As Russ mentions, complete coverage is probably overkill, but it came in 30SF boxes and I kept applying it till it was gone.

As Mr48Chevy suggested, I also looked at some of the car audio guy's suggestions, and I put a 1/4" layer of closed cell foam over all the interior surfaces I'd installed Killmat on.

The upholsterer who did the carpet put a nice jute pad, and that helps a lot. He even put jute and carpet under the seat. He also put carpet up the wall of the cab in back of the seat and carpet under the seat cushions, which probably helps a little with sound absorbtion in the cab.

All-and-all, I have about $100 in Killmat and foam, and maybe another $100 more in pedal gators, shift and steering column boots/bezels

Pic of the boots and bezels for sealing up the floor. (floormat is just a coconut door mat from HD that's been edge banded)



Killmat before the foam installation on the roof