Designed a roof rack wind fairing

So started playing around with CAD recently and got my first project made. I got a Front Runner Slimline II roof rack with an XKGlow SAR light bar and the gap between the bottom of the light bar and the cab roof was just tall enough to cause some whistling at street speeds, and on the highway the whistling was super loud. Front Runner had wind fairings for the Slimline II but none with a light bar cutout, so I decided to make one myself.

I designed the mount tabs to use the same mount screws for the Front Runner light bar brackets. As for the light bar cutout, designed it to be the same height as the light bar with an extra width to allow it to not block light when panning light to the sides using the light bar searchlight mode.

After installation, no more whistling noise even at highway speeds. On the second iteration, I am considering switching from aluminum to steel to make it stiffer and I fine tuned the width between the two tabs used to mount the fairing. The mount tabs were too far separated by about 0.5" on my initial design so it causes a slight bow out since the aluminum is flexible enough. Here is the result of the first iteration.

 

It probably going to rub off roof paint if it concerns you.

 

I have the fairing end high enough to leave just under an inch above the roof. Would the rubber wiper clip I have attached to close that gap also rub off paint?

 

I think the rubber will eventually rub thru paint, esp once it get dirt, road debri under it. Maybe clear protective tape would help under rubber as long as you keep after it. Good luck,

 

Got it, so more of a routine maintenance task for the tape. Thanks for the tip!

 

Looks good, but this was my first thought as well. Keeping it clean will only get you so far, I would also recommend some type of protective film between the rubber and paint. That fairing will likely be vibrating a fair amount once you get up to highway speeds and that will definitely eat away at your paint in no time.

 

You live in a nice neighborhood.

 

This ^^^. I’d put some of the thick ppf there.

 

That’s going to rub the paint off, just my opinion.

 

anything that is not firmly attached to your car will be doing a whole bunch of micromovements while driving, clear paint film underneath, or maybe a seal that has adhesive on it and rubs against the rack instead. I would stick to aluminum if possible, find a way to make it stiffer, or thicker. Steel will chip, then rust, then drip down. Do you think you could incorporate a polycarb window for the light cutout to up youre wind blocking?

 

The rubber will definitely rub through the paint on your roof. My old camper shell used something very similar on the tailgate. It eventually rubbed through a layer of 3M paint protective tape AND my paint.



I highly recommend changing your design to ditch the rubber seal.

 

Oh dang, do you remember how long that took for it to rub through to that extent?

I guess a question for the thread is for those that have wind fairings and don't have a whistling noise, can you guys do me a favor and measure how much the gap is between the fairing and the cab roof? I'm thinking I can just average the distances out and redesign the fairing to leave that much of a gap. I think if I'm to ditch the rubber seal design and just have a gap design, it's a trial and error to see if it will make noise

I'm thinking of going to go up from 1/8" to 1/4" aluminum for the next iteration to see if that makes it stiff enough to have a little less movement and vibration. I'm going to have to readjust the bend point on the rack to accommodate the higher bend radius of the thicker metal.

And as for the polycarb window, I found pieces that can be cut to fit the cutout, and I don't think it should defract enough light on the light bar side to affect the light dissipation unless someone had a different experience with this issue before (the angle of the fairing is shown below). I just need to figure out a good way to attach the polycarb piece to the fairing and still allow the polycarb to be changed out for any reason.

 

It took a few years, Probably wore through the tape in 2-3ish years.

The catch with the 3m tape is if you read the package it's only good for like 2 years, after that it yellows and cracks and becomes extremely difficult to remove because it comes off in tiny chips. It took me 2 hrs with a heat gun and scraper to get off the several inches removed in my photo. One of these days I'll buy an eraser wheel to remove the rest of it but I haven't really cared enough to bother.

 

What about double sided tape?

 

what if you wrap your roof?

 

Unique faring. I ran into the into the wind noise issue on my old setup with the slimline 2. I used a rubber seal to close the gap between the rack the the light bar. That took care of the noise but I still didn’t like it.

I ended up going with the big front runner fairing, it uses the same weather seal you’re using but they come with a strip of PPF so the seal doesn’t rub through the paint. I wanted to cut up the fairing to fit the light bar up there, I wanted the same setup you went for but I ended up ditching the hole idea. Here is the front runner fairing with zero wind noise.

 

First, stiffen it up with a rib across the top with a bend at like 120. If its stiff enough, that will allow you to get a closer fit to the roof, maybe not need the rubber strip.

 

Do you still have that wind fairing on? If you don't mind, do you mind checking to see how much is the gap in between the fairing and the roof? And also see how thick the fairing is?

Like a rib bend in between the 2 mounting tabs? Like here in the pic below? So like the mounting tab but a tab that stretches across the whole thing?
Since the top edge is so close to the light bar, I might not have enough clearance for that. Do you think it'll still work if I do a big rib on the bottom instead that stretches across the entire width?

 

There is no gap between the fairing and the roof due to the weatherstrip.
The fairing measured 2.0mm thick with the micrometer.

 

i think bottom would work too, just would be a more severe bend, but doable. any rib will help. A long piece of flat aluminum, hollowed out, in the wind, it needs something