Ask any roof cargo owner about the main advantages of their roof box and you’ll probably hear about the convenience and extra space it provides. But ask them what they don’t like about it, and noise is likely to be high on the list – that pesky humming or whistling sound caused by wind rushing over the top of the cargo box as you drive along. It can be pretty annoying, especially on long journeys, but there are ways to reduce or even eliminate roof box noise completely. So, if you want to enjoy a quieter ride without spending a fortune, read on for our tips…
Causes of Roof Box Noise
To understand how to stop your cargo box from making so much racket, first you need to know what causes this problem in the first place. Essentially, when air passes quickly over an object (in this case your cargo box), turbulence is created which produces vibration and hence noise. The steeper the angle between the airflow and flat surface of your car roof, generally speaking, the louder will be noise. This effect is more pronounced at higher speeds because airflow becomes faster than movement increased due to resistance of air.
Of course, it is the poor fitting Roof rack and not the roof box itself that is to blame for this problem in many cases. If your roof rack isn’t fitted correctly, it will create more turbulence than necessary as wind passes over it, exacerbating noise levels. Sometimes badly-fitting racks can also cause damage to your car Paint or Roof, so it really pays to take the time to get things right when you’re installing them – even if that means asking a professional for help.
Roof racks with consistent shape cause the wind to generate a whistling like tone as it passes over the top bar of the car. There is a technical name for it that is – Aeolian noise. If you are good at math, you can definitely figure out the precise point at which the wind starts making a whistling noise but for other mortal humans like me, this formula is overly complicated.
The volume of the noise is directly dependent on these following factors – drag coefficient, shape of the surface and speed of the wind as it passes over the surface. Drag coefficient is a formula which quantifies the amount of air resistance an object has as it moves through the air. Air flow, inclination and surface shape are the three factors that are used to calculate drag coefficient.
How To Stop Roof Rack Noise
There are a few different ways to go about reducing or eliminating roof cargo box noise, and we’ve outlined some of the most effective below.
Drive Slower
This one is pretty obvious. The faster you drive, the more noise it will generate (irrespective of whether or not you have a roof cargo box). So, if bringing down noise is your main priority, then driving at lower speeds is definitely something you need to consider. I understand that you hate to move like a snail but sometimes, we just have to accept the reality and make compromise accordingly. We know this isn’t always possible (or desirable), but even dropping your speed from 70mph to 60mph can make a big difference. Just remember: safety first!
Check The Roof Rack For Damage
A damaged or poorly-maintained roof rack is more likely to produce noise than a well-looked after one. So, before you start looking at ways to reduce noise coming from a roof rack, it’s worth making sure that your roof rack is in good condition. Just go out of your car and look for signs of wear and tear, such as cracks or loose bolts, and make sure that all the parts are clean and free from rust. Fasten the loose bolts with a wrench. If any parts need replacement, just do it rather than waiting for some mishap to take place. If you spot any problems, get them fixed ASAP – not only will this help to reduce noise but it will also improve the safety of your cargo box and all the belongings inside!
Remove The Roof Rack
I know you just spent a lot of money on that new roof box, but if you’re looking for the quickest and most effective way to stop roof rack noise, then removing the rack (and cargo box) is it! Obviously, this isn’t a viable option in the long-term. But taking off a roof box is not that complicated. So, if you are planning a long journey and want to enjoy a little peace and quiet, it could be worth considering. Once you reach your destination, simply put the roof rack and box back on – it’s that easy!
Wind Deflectors
As the name suggests, Wind Deflectors are designed for only one purpose and that is to change the flow of air. In other words, it will redirect the wind away from your roof rack (and cargo box) which should help to eliminate the whistling noise significantly. The best thing about these Wind Deflectors is that they are universal in nature and can be fitted to any roof rack with ease! All you need is a few minutes, some basic tools, and voila – no more whistling noise!
Padding The Crossbars
By cut off the flow of air, the noise coming from roof rack can be reduced to a great extent. I know the very concept sounds complicated on paper, but it’s actually pretty simple. All you have to do is to cover the smooth metal surface of the roof box and the noise will be gone in no time. So, what can be used for this purpose? Well, you can use pretty much anything that will break up the airflow and create a barrier between the wind and your roof box – things like crossbar pads work well! Crossbar pads, when attached correctly, can make the bar rounded. A rounded surface, compared to a completely flat one, will result in less noise. Moreover, these crossbar pads are made from soft rubber and that means, it will score high when it comes to drag coefficient. However, in order to reap its full benefits, you need to make sure that you are not driving at high speed. However, Crossbar pads can’t change the flow of air; all it can do is to change the drag coefficient.
Use Edge Bars Instead of Load Bars
Load bars are designed and developed for carrying heavier items. They have got longer bars and they have also got a large surface area. Unlike Edge bars, these Load bars have got square
Many wind fairing brands are universal and will fit most cars, but you can also get models in varying lengths. They simply clip onto the front crossbar and rest on the roof of the car.
Typically, you can expect to pay up to $120 for a wind fairing, although this will vary depending on brand and size. Some brands only make wind fairings compatible with their roof racks, so check this out before buying.
The price is also impacted by material and build quality. Realistically, you’ll want something fairly durable and of good quality in order to get your money’s worth. You can even find some wind fairings made from carbon fiber, but this isn’t that necessary.
