Technology has come a long way in the thirty or so years since the muscle car era, and modern cars now have very dense insulation throughout to reduce the noise, heat, and vibrations caused by the car's running gear, the road, and the wind. Luckily, companies like Hushmat sell this same OEM approved material in sheets and in kits for older cars, giving us the opportunity to make our old cars ride more like new ones, at least in terms of heat and noise. The Hushmat material is specifically designed to dampen vibrations, reduce noise, and act as a thermal barrier, and is self adhesive requiring very little prep to install. Although the material is dense, and heavy, it can be very effective even when used sparingly so it won't necessarily add a bunch of weight to your car. Since we were assembling our '67 Barracuda after paint, and since this car will be a regularly driven street car, we decided to try and make it as quiet as possible. Being a convertible, and prone to wind and road noise anyway, we figured this would be a good test of both the original replacement materials from YearOne, and the modern Hushmat dampening material.
Once we completed the job and got the car on the road, we can honestly say the results were nothing less than amazing. While we can't say our '67 Barracuda convertible rides as quietly as a modern luxury vehicle, we can say that it's the quietest riding A-body convertible we've been in, and we'd venture to guess that it's as quiet as far more modern cars like the Chrysler Sebring convertible. The best part is that now we have one less excuse not to enjoy driving our Mopars on a regular basis.
Before installing the interior...
Before installing the interior of our car, we sprayed the entire inner floor with rubberized undercoating. This will act as a sound and vibration barrier, and will help insulate the floor from exhaust heat and noise as well.
Before installing the interior,...
Before installing the interior, we'll add Hushmat self adhesive pads for modern, OEM quality sound, heat, and vibration dampening.
Engine noise and heat can...
Engine noise and heat can be transferred through the firewall and cowl, so we placed Hushmat in these areas as an additional barrier. We'll replace the factory firewall insulation with new insulation from YearOne, but it will now work in conjunction with the modern Hushmat material.
Installing the Hushmat insulation...
Installing the Hushmat insulation to the inside of the door skin, and the inner quarter panel in the rear, helps reduce noise and vibrations from the side. This is an area that didn't have any factory insulation or coating, so adding the Hushmat will make a big difference.
The Hushmat insulation comes...
The Hushmat insulation comes in conveniently sized sheets and cuts easily with scissors for a custom fit.
Hushmat recommends at least...
Hushmat recommends at least 80 percent floor coverage for the best results. We paid particular attention to the areas above the mufflers, and doubled up over the transmission and driveshaft tunnel to reduce noise and harmonics.
As you can see, we've nearly...
As you can see, we've nearly covered the floor with the modern Hushmat material. This is a trade-off between how quiet you want your car and how much weight you want to add, but even one layer of coverage will greatly reduce noise, heat, and vibrations.
Some Mopars had insulated...
Some Mopars had insulated carpet and some didn't. Since we're replacing the carpet in our car, we ordered a carpet set with insulation from YearOne.
Using a decibel meter, we...
Using a decibel meter, we tested the noise inside the car at 60 mph with the top and windows up.
We got consistent readings...
We got consistent readings between 70 and 80 decibels at these speeds, which is well within the comfortable range and is far below the levels (92 decibels and above) that cause driver fatigue.
When your car was put together...
When your car was put together at the factory, everything was sealed in place to the firewall and body with gaskets. Over time these gaskets get brittle and break, so we ordered complete body gasket kits from YearOne.
Sound and heat can sneak through...
Sound and heat can sneak through broken or missing rubber body plugs as well, so they should be replaced if they're missing or bad. Additionally, a rubber trunk mat will help insulate the car from noise and heat.
For comparison, we checked...
For comparison, we checked the noise levels behind the car with the car stationary and got decibel readings of nearly 90 with the car idling and close to 100 at 3,000 rpm. Our Barracuda is now far quieter inside than it was from the factory, making it easy to hear music or carry on a normal conversation while driving down the road. Since we plan on putting some miles on this car, we'll sure appreciate the quieter ride.