Aerodynamic wind noise suppression - 1951 Mercury custom

[mercguy1951]

Originally Posted by teoman

Those mirrors appear to be the culprit of the noise.

On some Nissans this was also an issue, so they made the front signaling lights protrude outwards to deflect the air past the mirrors. Cool solution but the slightest bump and you have to replace the whole headlight assembly.

There is only one small mirror on the left outside of the car. The A pillar has a drip rail starting at the bottom of the pillar and extending the entire length of the roof. That drip rail causes a lot of turbulence at the A pillar. Pretty easy to check with a listening tube stuck in my ear (ha!). It is just as bad on the right side where there is no outside mirror.

In any case, air gets trapped at the bottom rear of the door glass on both sides and enters the inside of the door because the stock weather stripping does not provide a good seal. It is just the nature of this 70 year old design. I drive the car on long trips to Rod Runs out of state, and at 75 mph the wind noise becomes deafening! It may not be possible to fix this short of a clear teardrop capsule to slip over it! I bet I could get 30+ mpg if I could do that.

[kach22i]

The rear view mirror appears to be at "ear height", so the wind noise will be at ear height.

Yea, between the hinged vent window and the side view mirror location there is going to more noise than a modern vehicle.

This YouTube video below claims cleaning you rubber door seals helps. Does your car even have rubber doors seals? If it does, what shape are they in?

https://www.youtube.com/watch?v=5sc3UdpHD0I

Published on Apr 15, 2012
A few simple ways to clean your door seals and to keep wind noise down in your car.

One of the comments in that video said this:

carforumwanker1 year ago

undo the door latch a absolute fraction. using a block of wood and a hammer tap the catch a fraction back and tighten. so the door is closing a fraction more .you cannot see any panel difference . but that tiny amount will form a better seal on the rubber .

On my S-10 I tore one of my rubber door seals forcing it open after some freezing sleet, I'm used to the extra noise now but in the winter I get a jet of cool air passing through it if the wind is just right.

[Daschicken]

Wind noise doesn't correspond directly with drag. If you got a 1st gen insight, you would still notice wind noise. In your case, look for any bad or missing door seals, exterior antennae (especially the whip style), thin side windows, panel gaps, etc. Also, you should look into making an undertray as the underside is a large source of both drag and noise.

Identify the areas producing noise, then apply the applicable solution, don't forget about sound insulation either!

[Ecky]

On my car, I added a weather strip right around the seam of the door, so there's no place for air to circulate at all.




A smooth underbody panel would be better than an air dam, and is also invisible from the outside:

[freebeard]

Another option: I thought "wind wings" might be the answer for the B pillar noise, so I built large Lexan wings that attached to the front of the door and extended out about 5". Even that was not enough to kill the noise on the B pillar.

Any ideas folks?

Welcome, etc. I wanna see this.

Can you be sure it's not road noise? Is it lined with Dynamat or anything? The suggestions about seals are good.

For the A-pillar: Reducing Windnoise / Raingutter Fillers – Gerrelt's Garage



Overall, for that body, I'd be torn between the style of Ron Courtney's X-51 and the Bertone BATs:


http://www.kustomrama.com/index.php?title=Ron_Courtney%27s_1951_Ford


https://en.wikipedia.org/wiki/Alfa_Romeo_BAT

[mercguy1951]

Guys, I've been building wrecked and custom cars for 58 years. I've even built and flown a 2 place airplane from blueprints. I've done all the correct seal tricks, used heavy insulation, I even have heat shields above the mufflers.

The problem is the shape of the A and B pillars is very old technology. What I am looking for is some kind of temporary deflector either mounted on the front of the car or on the A pillar that will smooth or direct airflow to prevent wind noise. Does anyone have experience with a front deflector that helped make your own car quieter? Thanks.

[Vman455]

I haven't gotten to it yet, but Hucho has an entire chapter on wind noise. I should have some free time Monday and will read through it.

[Vman455]

Well, here's why your deflectors didn't work:

"Wind rush noise is produced even if the flow is attached everywhere on the vehicle surface because the boundary layer flow is turbulent over most of the car. Hence, it is not possible to achieve zero wind rush noise. However, if the flow is separated, the wall pressure fluctuations are more intense by a factor of approximately ten, and much more wind rush noise is generated.... Usually the most serious wind noise problems are associated with the A-pillar area flow.... The flow velocity around this corner can be 60% higher than the free-stream air speed." Callister, John R. and Albert R George, "Wind Noise." Aerodynamics of Road Vehicles, ed. Wolf-Heinrich Hucho (Warrendale: Society of Automotive Engineers, 1998): 347-48.

Their suggestions to address it:
-radius of A-pillar as a whole should be as large as practical
-exposed rain gutters should be avoided
-auxiliary seal is needed to seal the A-pillar gap, and should extend down to where the door meets the body

[Vman455]

From the same chapter:

"R. Buchheim, et al, in a survey of fifteen production cars, found no correlation between aerodynamic drag and interior wind noise levels. One explanation for this lack of correlation is that the aerodynamic drag depends largely on the exterior airflow over the rear of the car where the wake separates from the vehicle. Conversely, interior wind noise depends largely on the details of the exterior airflow around the A-pillar and windshield."

So, start there. Adding an air dam would probably lower the car's drag, but it won't make it quieter--in fact, I'd bet it will increase wind noise as more air is routed over the body instead of under it.

[Isoldmysaturn:(]

Things the oems so for wind noise, and what members on here have had luck with shouldn't be so quickly dismissed. You have a wind noise problem, so have most of us at one point or another. I, for one, almost completely eliminated wind nose in my Saturn ion. This is a common mod around here.

The problem with a deflector is it will just move the point of noise generation, and add a bunch of drag for the trouble. It is a much better idea to try to smooth the airflow, and this will usually have added side effects of a more stable car, less drag, and happy driver.

Heavy insulation is a not so good approach, I would remove it from the floor of that's where you have it, a belly pan smooths the air so there isn't nearly as much noise to be heard in the first place, but will also block a lot of what's left. For the top, reshaping pillars may be a much better use of your time than attaching big flaps, and bullet mirrors, panel gap seals, replacing worm weather seals, and insulating where the front fenders end in the for jamb with carpet oad or similar insulation would all help your case much more.

I doubt anyone here has tried a flap, because that's the opposite of what this forum is about, but please don't assume our ideas are bogus just because our cars are newer, we're just trying to help you.