How To Stop Wind Noise On Roof Racks (4 Easy Ways)
When you’ve been driving fast with a roof rack it tends to increasingly get louder or even start making whistling noises. Having sounds coming from right above you when traveling is worth avoiding, especially when using a sunroof. So, why are roof racks loud at all?
The amount of noise coming from a roof rack, roof carrier, roof box or cargo basket depends on the shape, the angle at which air hits, and the speed of the air moving by. You can influence all of those three factors either by manipulating the rack itself or your driving style.
Based on this, there are some working solutions – apart from removing the roof rack entirely, which is always the obvious option. But probably not the one you were looking for, since roof racks don’t necessarily need to be removed when not in use. Stopping your roof rack from making annoying sounds is not that hard.
Noises are only one aspect a roof rack affects your car. In order to understand how it can generate whistling sounds in the first place, and what we can generally do to stop that from happening, let’s look at the underlying physics.
(I promise I’ll keep it simple!)
Why roof racks can get noisy
The phenomenon is called an Aeolian noise and can basically occur when air moves at certain speeds around an object of a certain shape, hitting it at a certain angle. In our case, it depends on the shape of a roof rack’s parts exposed to wind, the angle at which air hits the rack, and the speed of the air moving by. You can influence all of those three factors either by your driving style or by manipulating the rack itself.
Just think of what you need to do in order to whistle with your mouth: particular lip shape, airspeed, and angle. If one of those is not quite right, the only audible noise is the spit exiting your mouth, but no fine-tuned whistling. Just as learning to whistle yourself requires everything to fall into place, so does your roof rack before it can whistle.
Manipulate just one factor to disrupt airflow and it will stop making noises: Shape, speed or angle.
Buy an aerodynamic roof rack
Roof rack manufacturers are of course aware of this issue and developed solutions to eliminate it from happening without any extra steps from your side. If you are not yet the proud owner of a roof rack or cargo basket, consider also factoring the aero properties into your buying decision. There are roof racks – specifically the crossbars – specifically designed to prevent this whistling issue.
Look for product descriptions like “aerodynamic and quiet”, “includes wind fairing”, “wind diffusion”, or “wind tunnel tested”. Here are the best-rated aero roof racks on amazon.
If in doubt, the shape is a good indicator of the aerodynamic properties of crossbars. The more they resemble a plane’s wings, the better for airflow and noise. Square-shaped bars are obviously less aerodynamic than oval ones. Their shape is highly dependent on what is mounted on the roof rack and what attachments are needed.
With all that being said, there is a factor that can not be covered by the roof rack itself, and that is the angle of the vehicle’s roof, which dictates the angle the rack is sitting at and is hit by the wind. Even in the rare case, this is an issue, there are of course multiple ways to go about it.
Fit a roof rack wind fairing
What are roof rack wind fairings? Wind fairings are simple, often concave, shields, that are mounted to car roof racks to deflect frontal winds in order to greatly reduce noise and improve fuel economy. Investing in one can quickly be worth the cost by the resulting fuel cost saving.
So, a wind fairing is basically a spoiler in front of the roof rack to change its frontal profile and break wind before it hits the actual rack frame. This achieves two things: changes the shape exposed to wind and changes the angle wind hits the parts behind it.
If a wind fairing doesn’t come with your roof rack, there are many aftermarket options available. The easiest to find and fit are of course offered from the same brand as your rack.
Many wind fairing brands are universal and will fit most racks, but you can also get models in varying lengths. They simply clip onto the front crossbar and rest on the roof of the car. As you would expect, brands with their own roof rack line-up tend to make their wind fairings compatible with only their roof racks.
How long should a wind fairing be? The fairing should cover as much of the roof rack’s cross-bars as possible in order to deflect as much wind as possible over the bars. In the best case, it can be secured to the towers (feet) on either side of the rack. The less air hits the actual roof rack, the greater the effects of the fairing.
How much are roof rack fairings? Generally expect to pay around $50 and up to $120 for a wind fairing (here are amazon’s best offers). Prices vary depending on brand, material, and size. Size and safe fitting are the most important factors here. It should cover most of the length to have the best effect. Material is not something that influences the performance much, so don’t get sucked into fancy high-end constructions. All it needs to do is deflect wind and mount securely.
Wrap crossbars in pads
What are roof rack pads? They have several uses, most importantly to protect your roof rack. That may be from any cargo, that is directly mounted onto the crossbars like a kayak, surfboards, paddle-boards, or all other cargo without the use of specialized mounts (like bike racks). But also from weather and corrosion when not in use. As a side-effect, they change the shape of the crossbars, also affecting airflow.
These are extremely easy to install, just wrap around the crossbars of your roof rack. As with fairings, there are many shapes and sizes of roof rack pads. There are also pads designed by roof rack manufacturers to perfectly fit their rack. For pads, fitting is usually less important apart from the length. Again, look for the most coverage you can achieve by padding your rack.
As far as prices go, you can expect them to be around $40 for a pair of roof rack pads, depending on length and manufacturer. Some come with additional accessories like straps and hooks. One that’s available in many lengths and colors would be the rack pad from the reputable brand Dakine, which can also be found on amazon.
As with roof fairings, there are ways to DIY these pads yourself, if you are handy. This is the easier way to do yourself out of those two options. In order to disturb airflow and reduce noise, you could do this with rope, cord, or any fabric wrapped around the crossbars. Just be sure this is done securely and safely. You wouldn’t want any of your attachments to fall off due to high winds while on a highway.
Change your traveling speed
If all else fails, let’s remember one of the three factors required to create noise from air passing by: airflow speed. Of all the measures you can take, this is the easiest and cheapest one to do and it can be done immediately. Just change your speed by 5mph up or down and listen for changes in the sound profile. (Obviously within the maximum speed limit).
You may notice the noise level still be varying even when going at a certain speed. The airflow generated from moving through the air is only one aspect. There is still wind to factor in to arrive at the relative air speeds hitting the car and roof rack. Depending on surroundings (wind-sheltered or not), wind direction, and wind force, wind can be enough to make a roof rack whistle when it otherwise wouldn’t. Simply counteract by regulating your car’s speed to change relative wind speed.
Important Caveat
With all that, we still need to keep in mind, that the actual roof bars are only the connection between the car’s roof and the various carriers and attachments that can mount to a roof rack. With whatever is on top of the rack it’s significantly harder to noise-cancel.
In the simplest case, turning a bike’s pedals or handlebar will do the trick. Bike covers are another, but not free, option. Or propping up a cargo box to change the angle wind hits it. To find out which part of the whole system actually is noisy, try and use different configurations to eliminate silent parts to find the loud ones.
