Cars get built every year and the eternal question arises, how can I make my lowrider ride as quietly as my new car? Car makers are working overtime to remove road noise from the daily commute and each new model is quieter than the previous one. Panels are now double or even triple walled with an anti-vibration barrier of some type to aid in the cancellation of these noises. Every vehicle has some sort of sound deadener in it. Most are some type of asphalt-based material and older vehicles even had a straw-type heat barrier as well. But we still haven't properly answered the question, have we?
Well, we posed this same question to Scosche Industries. According to Scosche, noise can be controlled three ways: Vibrations may be damped, noises may be blocked by a barrier, or noises may be absorbed. Webster's definition of "damp" is to diminish the activity or intensity of. So when applied to our case, it's to diminish the activity or intensity of the vibration. Absorbing is easily understood and visualized as a sponge.
As for the barrier, we can think of the walls of a recording studio where both of the above concepts are combined. So there's a thick layer of damping and a layer of spongy stuff. Because of the density, the barrier also offers an insulating effect to keep things cool. So with the definitions out of the way, how do we apply these concepts in a car?
Vibrations occur all over the car. A damped car will not only isolate the outside world, but the reduced vibration will let the speakers perform as they were meant to, turning your ride into a mobile concert hall. The areas that we always damp are the doors, trunk lid and trunk walls. Hey, what about the rest of the car? The rear deck or package tray should also receive attention as it's the noisiest link between you and your bass as the sole passage from the trunk to the interior compartment.
On a two-door vehicle, don't forget to give the rear side panels attention. Just because there isn't a door right there doesn't mean that it won't vibrate. As for the most neglected part of the car, that would be the roof. No one seems to care about it until you hear the unforgivable chatter of the roof rails slapping against the sheet metal after the bass has thoroughly destroyed the bond between them. If your car is a keeper and you want some serious bass, don't neglect your roof.
The most effective use of an absorbing material is under the hood. The engine is a beast that can not (or should not) be tamed. To aid you in hearing the tunes that you want to hear, a layer of absorbing material can be used under the hood. We know that you wanted something more showing, but they don't help you contain the growl.
Additionally, the growl and heat from the engine will find their way through the firewall. To keep them out, you will need a barrier of protection. The barrier material is best suited for the firewall and is the best option for keeping out the transmission's and the exhaust's heat and noise from the floorboards as well. You want to hear the pipes wrapping with your windows down, but at the end of a long show day, you want to just chill and let the oldies wind you down.
The installation of these materials is very straightforward, and aside from cleaning up dirt and stuff, the only other thing that you have to do is take the interior apart. We know that's sometimes easier said than done. Some things to keep in mind are: the adhesives of these materials won't stick well to a dirty or wet area, so clean things up as best you can before applying the material. The barrier material is ultra-thick and isn't very pliable, so pre-fit the material before taking the adhesive backing off.
Lay everything out where you would like it to go, and if the bend over the floor rail or the transmission hump just isn't working out, cut the big piece down into smaller workable pieces. Keep in mind that the trunks on some old cars had a textured paint on them and that the damping material won't adhere to it very well. The two options are to strip it off before applying the material, or look into the sprayable damping materials on the market for these tough areas.
While on the subject of damping materials, keep in mind that they will only work if applied directly to the sheet metal. They're ineffective if applied to plastic or paper weather shields found on most late model cars. And our personal suggestion is to be aware of what you're covering. Some people just don't care and cover everything. In the interest of serviceability, we like to take into consideration the nuts and bolts of the window tracks, power window motors, door panel guide holes, etc. Restorations will need to be serviced at one time or another. Try not to make it harder on yourself.
So armed with the knowledge above, let's take a look at the basic installation of said materials. The car that we used here was being restored so a carpet was also installed. The best time to do these types of things is when they're already out. So let's follow along as our ride gets the silent treatment.
 Today's install is very straightforward....  Today's install is very straightforward. Only the key areas were hit so a damping material for the side panels and doors was used in conjunction with a barrier material for the floors and firewall and a clean carpet kit to boot. |  Disassembly is the first order...  Disassembly is the first order of business. Seats and center console first, now the seat belts, carpet and factory carpet padding are removed. Once out, vacuum the area and wipe it down. |  We'll begin with the barrier...  We'll begin with the barrier material. With the adhesive backing still in place, we'll pre fit and precut the panel. It's best to lay the material down as flat as possible, then trim the edges. Once everything is set up, start laying down the material, elevating one end and pushing the material down so as to avoid any air pockets. |
 After completing the rear...  After completing the rear floor panels, we laid down the front floor panels, then moved on to the transmission hump and finally the firewall. |  With the flooring complete,...  With the flooring complete, the ACC pre-molded carpet kit was installed. When installing these kits, it's important that you fit the kit first and trim holes after everything's in the correct position. |  Moving on to the doors, we...  Moving on to the doors, we started by removing the paper weather shield. Since these doors were fairly clean, we wiped them down before applying the damping material. |
 The material's applied, leaving...  The material's applied, leaving all of the factory holes and bolts accessible. Once laid down by hand, the material can be heated for better forming and closer adhesion. Once the inner and outer panels are complete, you can move onto the other door (or doors). As for us, this is the last panel on the last door. | | |