Road noise and how to reduce it

[1STMP]

One of the stark differences in older cars and newer ones is the amount of noise that is heard while driving at freeway speeds.
I can go for a ride in a newer Challenger and feel somewhat isolated from the outside world.
The same road and duration in my '70 Charger and I feel overstimulated, almost like you feel after leaving a live musical event.
It isn't all bad but I wonder what can be done to take the edge off just a bit.
Several factors add to the noise so I think that there are areas to address to limit some of the noises that we don't want. For me, part of the problem is that due to some hearing deficiencies, I may have a hard time identifying what is causing the noise that I want to scale back.
I don't want a silent car. Hell no......
I just want to scale it back a little. I just need help finding out what is responsible for the noise that bothers me the most.
First off, I have NO drone. This car has somehow never had a problem with overheating or exhaust drone noise. Somehow, I dodged those two bullets.
Secondly, I have tires that are sticky and wide. 100 treadwear tires do not last long and are not great for wet weather.

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How much of the noise that we have is from the wind itself? Looking at new cars, you see hidden rain gutters, flush bumpers, wheels pushed to the edges of the body and mirrors with rounded or pointy shaped sections facing forward. For contrast, look at this:

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Starting from the rear, you have a bumper that has a noticeable gap from the body where air can get disturbed when flowing by.

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Moving forward, there is the rear wheel opening that has a gap between the tire and body. Above that there is the quarter window taper which has a bit of a pocket in it at the bottom. The side view mirror is almost flat at the front side. Above that, the A pillar has the start of the rain gutter and the wing window. The windshield wipers certainly grab the air along with the front wheel openings but how about the huge sugar scoop grille?

Looking at a late model, you can see a lot of differences if you look close.

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As you might expect, the recessed grille is a step backward for aerodynamics but was deemed necessary to get the styling right for this car. Still, look at the gentle shape of the front bumper, not how the tires are out to the edges. The windshield wipers are tucked down and out of the air flow. The mirrors have no flat or blunt faces either.

Part of what attracts me to the classic cars is the styling. I'm sure that you feel the same way. Because of this, we are limited as to what we can do in terms of styling changes to reduce the noise. I do have my tires out wide but not for aero...It is because I loved the NASCAR look:

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I need windshield wipers. I love the way the grille looks. I may change to the late 1970 style racing mirrors though that alone will result in almost no noise reduction.
What else can be done to reduce noise?

In 2012, I did add a fair amount of "Rattle Trap" matting.


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The late models have flush mounted windshields. This can be replicated but now I'm looking at a custom windshield or shrinking the stock opening and fitting the stock windshield, both options are not cheap.

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Flush door handles? Hmm...Hard to do without going custom....plus, I like the stock design.


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Hello, @Kern Dog
Though you point out some
possible noise causing
areas, bear in mind that
Cadillacs, Lincolns, and
Imperials of the same year
as your charger, rode
whisper quiet while sporting
the same traights as you
point out, that may be
suspected noise causers.
If I may ask;
Have you installed any
polyurethane bushings?
Body mounts, K-frame,
Control arms, Spring Eyes,
Motor Mounts, etc, are
great enhancers for
performance, but transmit
vibrations and noise.
Does that new Challenger
have rubber bushings in
most of the above listed
areas? My guess is yes,
though they may be of a bit
higher durometer than the
the old land yachts used.
I run rubber bushings
throughout on a vehicle
that is 80 years old. The
only thing I hear when
crusin' down the road is
the hypnotizing rumble
of the 440, and a little wind
blowing past the windshield
seal.

 

[Kern Dog]

I only have urethane in the strut rods and sway bars. The upper control arms were rubber bushings until I swapped in the QA 1 UCAs. Imperials had exhaust manifolds, a closed element air cleaner, mild cam, most of the time a single exhaust system that was much quieter. They also had taller tires, softer spring rates and shocks.
I think that the lion's share of the noise is the engine and exhaust system. Swapping to a hydraulic cam would cut out the valvetrain clatter but I'm not interested in toning down the exhaust system. I actually think the exhaust system and mufflers that I have are too tame. I miss the Flowmaster sound.

 

[1STMP]

I only have urethane in the strut rods and sway bars. The upper control arms were rubber bushings until I swapped in the QA 1 UCAs. Imperials had exhaust manifolds, a closed element air cleaner, mild cam, most of the time a single exhaust system that was much quieter. They also had taller tires, softer spring rates and shocks.
I think that the lion's share of the noise is the engine and exhaust system. Swapping to a hydraulic cam would cut out the valvetrain clatter but I'm not interested in toning down the exhaust system. I actually think the exhaust system and mufflers that I have are too tame. I miss the Flowmaster sound.

Thanks for the response
@Kern Dog
I saw the pic of the sound
deadener.
Is it used throughout your
car?
Floor, firewall, doors?

 

[Kern Dog]

I refused to pay for Dynamat. I went with a generic alternative. It is from half way up the firewall, across the floor and under the rear seat. I put strips in the doors on the inside of the outer skin. Same behind the quarter windows. If I would have been thinking, I would have put it on the roof skin before having the headliner done. I almost wish I had a tear in the headliner.....It would motivate me to pull it, insulate the roof skin and redo it!

 

[Randy Wilson]

What brand did you end up going with?

Softseal

 

[Black_Sheep]

I did a layer of FatMat from the firewall to under the back seat, mass backed carpet and stuffed fiberglass sound insulation into the back seat cushions. There is also FatMat under the package tray and on the trunk divider. Even with the loud Flowmasters I can hear the radio and carry on a conversation…

 

[Bighouse]

A slant 6, auto, squishy 14” tires and 2.76 axle should quiet it down…

 

[dart4forte]

Speaking of road noise, reminds me when me and my buddy rode down to Spring Fling in my 67 Dart GT. All the way down we had this persistent whistle. Slow down the whistle would subside, speed up the whistle would get louder. Every time we would stop a detailed check of every nook and cranny on that car. Just couldn’t find it. Got down along the I-5 between Stockton and the Grapevine, very few places to stop but we managed to find a place with little traffic noise. I was bound and determined to find that whistle.

Anyway, finally narrowed it down to the front of the car. Turns out it was a piece of trim. On the 67 Dart GT there’s a shark fin piece of trim that houses a blinker. I had removed the lense to fab up a piece of plastic to replace the faded piece. The trim covers a hole on the front of the fender where the light harness runs up in the trim piece. The wind would enter that hole and escape through the opening for the blinker lense. A small piece of paper towel shoved in there along with some wadded up painters tape eliminated the whistle.

It sure made for funny conversation the rest of the trip.

 

[1 Wild R/T]

When you shut off the engine at freeway speeds, what changes, and what stays the same?

Same:
Tires on the pavement
Wind over and under the body
Rear axle And driveshaft spinning, but zero load.
Wheel bearings

Changes:
No engine noise
Reduced or altered transmission noise
No exhaust noise.

So if it changes much or gets rid of the undesirable noise then you know where to look..

Yeah, swap in a Tesla powertrain...................... Not!!!!