How to Install Sound Deadening

Posted on January 14, 2022 by Jefferson Bryant in Interior, Tech // 0 Comments

Nothing ruins a sweet sounding system more than a trunk that buzzes and doors that rattle. While most cars come with some sort of sound deadening from the factory, it is not up to par with the addition of high-quality audio gear. Along with that, the older the car, the lower the quality of materials used for sound deadening, and with the heavy resurgence of muscle cars, this becomes a serious problem.

To solve this problem, Dynamat offers numerous products to fit practically every application. The trick is deciphering which product is the best for which application. Each section of a car has its own types of noise, and requires specific properties in sound deadening. Floors have different properties than doors, while firewalls need noise and thermal reduction. Before purchasing sound deadening, you need to break it down and choose which areas you are going to deaden and what properties each section requires.

Doors: wind noise, mechanical rattles, and audio vibrations

Floor: road noise, drivetrain, and thermal reduction

Firewall: Thermal reduction, road noise, and engine noise

Trunk: Road noise, mechanical rattles, and audio vibrations

Rear Deck: Audio vibrations and mechanical rattles

Roof: Wind noise and thermal reduction

With each section broken down, the choices become simpler. While searching the Dynamat website, www.Dynamat.com, each type of material is listed with its own dampening characteristics. Some materials are suited for a wide range of applications, such as the Dynamat Extreme, which is specifically formulated to reduce road noise and vibrations on virtually all sheet metal.

Other products have specialized properties for specific panels. Dynaliner is a specialized foam pad that blocks heat, reduces wind noise, and isolates vibrations, making it the perfect solution for door panels, and when used in conjunction with Dynamat Extreme, floors and firewalls. Dynamat even has Hoodliner, which not only reduces noise, it reflects 97% of the radiant heat from the engine, which helps to protect the paint.

There are also a few materials to stay away from. Spray-on sound deadeners tend to cause rust as experienced on the 1971 Buick GS convertible project. For this article, the old OE mat and some rust-causing spray-on sound deadening is removed and replaced with Dynamat Extreme and 1\4” Dynaliner. The end result is a solid, noise free ride that will keep the music in and the rattles out.

1. A few years back, the entire interior sheet metal was covered with a spray-on liquid sound deadener. While it made a slight difference, it wasn’t worth the effort, or the expense. Add to that the fact that it is water based and resulted in a lot of little rust patches. This stuff is not advisable.

2. Using a paint scraper, some MEK (methyl Ethyl Ketone, similar to acetone but evaporates slower) and some good ol’ elbow grease, the spray-on stuff came off in chunks. It took hours to get the car clean again.

3. With the back seat area clean, the rusty areas need some attention. Using a chip brush and some Mar-Hyde One-Step, the rust was converted from body cancer to black oxide primer. On areas like this, this stuff really works and keeps the rust from spreading, which could eventually lead to the floor needing replaced.

4. The removal of the original mat is a messy endeavor. Using a metal spatula, the old mat is scraped off the floor. Sometimes it comes off in small pieces, tearing the paper. In some areas, there isn’t enough room to get the scraper under the mat. Cutting the mat down the center provides an easy solution.

5. This piece came off as a sheet, showing the ineffectiveness of the OE mat.

6. The original firewall jute padding had disintegrated to a mess that always covered the carpet with lint. The padding practically fell off in my hands.

7. The factory used a little spray adhesive to hold the jute pad under the dash. The scraper made quick work of removing it.

8. The entire floor pan gets vacuumed so the new mat will stick to the floor and not the dirt and sand. The final step before applying the Dynamat is wiping everything down with MEK to clean the metal of old adhesive and grease, so the new adhesive sticks.

9. The Dynamat is available in project kits or bulk packs. Shown here are a door kit for 2 doors, a trunk kit, and a bulk kit. The bulk kit is for the floor and contains 9 pre-cut sheets totaling 36 square feet of mat.

10. While Dynamat Xtreme does not require heat like some products, laying it outside in the sun does make it a little more flexible.

11. First a sheet of Dynamat on the floor for fitting. This piece fits great, so it won’t be cut down. The paper backing is removed after test fitting the sheet on the floor. The adhesive is ridiculously sticky, so wearing old clothes is advised.

12. The mat has a foil back, so it conforms to the corners and corrugations of the floor pan.

13. Using a rubber roller, the mat is pressed into the crevices and corners of the floor. This step is crucial for not only achieving proper sound dampening, but for better adhesion as well.

14. The tranny hump presents its own obstacles. A sheet of trimmed mat is laid over the hump with the paper still in place.

15. Using a razor knife, the mat is trimmed in several places to create a pattern for the hump.

16. With the paper removed, the mat is applied and given the roller treatment. Anything more than 75% coverage is adequate for proper sound deadening. Notice how the section behind this mount for the console is left bare. This assures the console will fit properly and the section cut out is re-used directly behind it.

17. When covering the floor pan, the wire chase running to the rear of the car needs attention. Using the rubber roller, the mat was pressed into the channel. The mat is cut away from the factory metal tabs that hold the wire loom in place.

18. The wire loom lays down in the chase just like normal, which keeps the carpet flat without lumps.

19. Since this is a convertible, the rear seat support tray desperately needs sound dampening. The factory didn’t pay any attention to this part of the car and after 35 years, it rattles quite a bit. This is a no waste operation, any mat removed from a sheet should be utilized elsewhere.

20. The seat belt holes get covered during the installation. A razor makes quick work of the mat to uncover the boltholes.

21. The entire floor looks like a foil doggy bag. The foil backing helps reject heat, making the interior a cooler place to ride.

22. The doors have their own vices. The outer skins buzz and rattle and induce wind noise. A few well-placed sheets of Dynamat cures that problem. Sliding the sheets in through the window opening is simple enough. The door skin should be wiped clean before applying.

23. Once the sheet is in place, the paper backing is removed and the rubber roller comes out again, pressing the mat in place.

24. The outer panel of the door is home to the window cranks and regulator, 2 sources of rattles. The mat serves its purpose well here.

25. Using the edge of the roller to get into the creases maximizes the effectiveness of the Dynamat. Leaving the edges and corners rounded, and not square, limit its capabilities.

$26.The final step in sound deadening the GS, is the Dynaliner. This 1\4” foam product installs just like the other mat and rejects heat and wind noise.$

26. The final step in sound deadening the GS, is the Dynaliner. This 1\4” foam product installs just like the other mat and rejects heat and wind noise.