FL5 Air Guides On a FK8

Ah, the infamous air guides on our beloved FK8s. Let’s be honest, they’re the epitome of “meh.” These little plastic things pretend to guide air, but they’re more like lost tourists giving directions in a foreign city. The engineers must have had a lightbulb moment like, “Hey, we forgot about cooling the brakes! Quick, grab some random, flat plastic pieces, and let’s pray that the ricocheting air somehow cools them down.” Talk about innovation! cue eye roll

Air Guides serve the crucial purpose of augmenting the rotor and caliper’s heat dissipation rate by improving the airflow and optimizing air cooling to these vital components. Their primary function entails enhancing the efficiency of heat rejection.

Like many other FK8 owners who track their cars, I have struggled with the “Brownbos” and consistently overheating the brakes. I have tried many different pad combinations but still struggle with my front brakes getting too hot. Just for your reference, my pad choices over the years on the FK8 have included Raybestos ST-43, Hawk DTC 60 and 70, Carbotech XP10, XP12, and most recently XP20. As for the rears, I used Project Mu Club Racers for a while and then decided to try a more aggressive compound, Winmax/Paragon R5.

Here’s a pic of the temp sticker to give you an idea of the crazy temps I’m seeing. I know it’s a bit hard to read, but it’s showing a whopping 490°F! That’s seriously scorching hot!

I also have Girodisc front rotors installed which made a huge difference in brake cooling compared to the OEM 2-piece rotors. Along with the rotors, I run the Girodisc titanium shims too. Now as for Titanium shims… the jury is still out. I mean yes, the science is there and it makes sense how TI shims reduce the heat transfer. But remember, heat is energy and it all has to go somewhere. Where does it go if it’s not going to the caliper?

Below is what my current front setup looks like.

Yeah, maybe I should reconsider how I drive. I mean, the Spoon FK8 is a beast! It can go for a whole 25 hours of Thunderhill with its factory Brembo’s, Paragon two-piece rotors, and endless pads, without a single brake issue. Those skilled race car drivers who handled the Spoon car during that time were top-notch. There’s no way I can outdo them! So maybe the problem is me?

Additionally, there are also several FK8 owners who are much quicker than I and do not encounter the issue of caliper discoloration, commonly referred to as the “Brownbo’s”.

Since my initial track day with the FK8, I have encountered a persistent issue: the unsightly discoloration of my Brembo brakes. Determined to enhance brake cooling and optimize performance, I embarked on a quest to ensure optimal brake function and preserve its appearance. Ensuring the utmost control and reliability during my track days has become my foremost priority.

Currently, as of August 2023, there is a lack of readily available FK8 brake cooling enhancements accessible to the general public. Although there are options such as BBK’s, two-piece rotors, and Titanium shims, no products exist on the market specifically designed to increase airflow and aid in brake cooling. While a company claims to have developed a brake ducting kit, it has not yet been perfected nor widely adopted.

That’s why I was super stoked when the FL5 came out and was claiming to have better brake cooling. I was like, “How the heck did they pull that off, considering the FL5 and FK8 have practically the same brakes and suspension setup?” I couldn’t wait to see how they did it!

This illustration below depicts the implemented approach regarding the optimization of the brake duct shape and improvements in the air plate/guide. Additionally, the relocation of the air duct inlet more towards the center of the bumper is undertaken, resulting in heightened air velocity.

Honestly, I gotta say, the only thing that caught my attention was that air guide thingy attached to the suspension. I mean, if the new and improved brake duct, now more centered on the bumper, made even the tiniest difference (like, seriously, a 0.1% improvement), Honda’s marketing team would spin it as a major upgrade. They’d probably use that data to convince folks to buy this car (although, let’s be real, they don’t really need any help selling these badboys!). So, I was sold on it being the air guides that made the drastic improvements in cooling.

below is a screen grab from the Honda press release kit for the FL5. As you can see they claim more airflow to the rotors by way of increased airflow and routing of the air.

So, now that I’ve found out that the FL5 air guide was a whole different design and being that the front suspensions of the FK8 and FL5 were pretty similar, I had a sneaking suspension that these would be interchangeable with both chassis. I went online to see if I could find the part number for the FL5 air guide and hoped that it was a direct bolt-on upgrade for us FK8 owners.

Upon thorough research, I embarked on a quest to unearth the elusive part numbers for the FL5 brake air guide. Alas, the task proved to be a formidable challenge, testing the limits of my resourcefulness. In my usual fashion, I promptly sought solace in the realm of Hondapartsnow.com, relying on their meticulous cataloging system. However, to my dismay, the sheer novelty of the 2023 FL5 rendered its parts uncharted territory, and devoid of any visual representation. (Basically, there is no option to select a 2023 model on their site)

So, I had to put in some serious effort to track down these part numbers and hopefully get them ordered. After trying out a bunch of different search terms, I finally stumbled upon this helpful site with the diagram and all the part numbers for each air guide.

I had never heard about that website. So, I just snagged the part numbers and Googled them to find a safer place to order from.

For reference here are the part numbers. And the official name for them is “air intake plate”

After pasting the part numbers into the Google search bar, the first site that popped up was in fact, Hondaprtsnow.com. Again, since the car was so new, there weren’t parts lists and diagrams for the FL5. But if you happen to know the specific part number, you could search for that part number on Hondapartsnow’s site.

So, get this – those air guides (aka air intake plates) were a steal, only 20 bucks a piece! I was like, “Heck yeah, I gotta try these on my FK8.” Even if they don’t fit, I’m only out for 50 bucks. Talk about a no-brainer!

They arrived at my house a few days later. Here is what they looked like.

It was too good to be true… these weren’t a direct bolt-on…boooo

Hold your horses, my friend! Let me break it down for you real quick. These bad boys might not be a perfect fit, but they’re darn close! Just a little tweaking and they’ll be ready to go.

Below I will go over the process of what is needed to get them to work.

Please note that it is not necessary to remove the caliper to replace the old FK8 ones with the new FL5 ones. The removal of my calipers was only done because I was also rebuilding them with new seals, while simultaneously upgrading the air guides. (caliper rebuid will be in an upcoming blog post)

Below you can see the stock FK8 air guide and how it is attached to the damper fork with only two 10mm bolts.

The second 10mm is slightly hiding (becasue of the angle that the picture was taken)

Simply loosen both 10mm bolts and the air guide will come right off. (again you can do this with the caliper in place)

You can now see the two threaded holes on the damper fork which the air guide bolts too.

Now take one of the 10mm bolts and using the top hole, loosely bolt the FL5 air guide on. You will notice right away that the bottom of the air guide interferes with the nut on the suspension linkage.

I used a sharpie to trace around where the nut hit the air guide. Then, I took my band file to grind out a notch so the stopper linkage nut would now clear.

So, I just took out a bit of plastic material, and bam! The FL5 air guide could totally squeeze past that stopper linkage nut. And guess what? The second bolt hole on the air guide lined up perfectly with the damper fork. Excited, I quickly screwed in both those 10mm bolts and secured them in place. Voila!

Below you can see the small amount of modifying I had to do. The one on the left is the modified one and the one on the right is the unmodified stock one.

For all the pessimists out there who think that the brake ducts from the FK8 and air guides from the FL5 when mounted to the FK8 won’t line up and receive adequate airflow. Please take a lot at my science experiment below.

I’m sure this rudimentary way of measuring if the airflow is aimed at the air guide isn’t the most scientific method. But it does show that the light coming through the bumper brake duct and out the wheel well is lining up with the FL5 air guide.

The light goes in the front bumper (as air would)

and comes out one small hole in the wheel well.

Then, it hits directly center on the FL5 air guide.

As you can see from the comparison below, the FL5 air guide is much more like a scoop that helps to force air directly onto the rotor/caliper. Whereas the FK8 one looks a lot less impactful.

Below are just a few other random shots of the fitment around the stopper linkage nut.

Then a shot of how the air guide now directly aims the air at the brake rotor/caliper.

Everything was reassembled.

When maneuvering at full lock in either direction, there is ample clearance. It is important to note that the brake hardline does not make contact with the FL5 air guide. Additionally, none of the suspension components come into contact with any part of the FL5 air guide. Lastly, it is worth mentioning that the CV axle boot does not rub against any section of the FL5 air guide. Rest assured that all these potential points of contact have been properly addressed and there is no interference, rubbing, or any sort of contact witht he new FL5 air guide on any part of the FK8 suspension/drivetrain.

Due to the FL5 air guides larger size, it is tight though. but again noting rubs.

I am confident that this upgrade will effectively decrease overall brake temperatures. While I don’t have empirical data to support this claim, my understanding of the increased surface area and superior design of the air guide leads me to believe that this modification will undoubtedly have a positive impact. Although I have not tested it on the track yet, I am convinced that this enhancement will successfully aid in reducing brake temperatures.

I am thrilled to share this valuable information with as many individuals as possible, ensuring that you can promptly benefit from this cost-effective brake system modification. It is my sincere hope that others will seize the opportunity to enhance their braking performance through this economical alteration.

I believe that this development in the interchangeability of air guides is highly beneficial for all owners of the FK8. However, it is important to note that this enhancement does not address the persisting concern of the dust shield squeal caused by rocks becoming lodged. Regrettably, this issue will continue to pose challenges for all of us. Hpwever, you should all be jumping for joy now becasue there is a cheap, OEM way to improve your brake cooling effenciency on your FK8.

I am filled with gratitude for taking the time to peruse my blog post. I am genuinely committed to delivering content that is nothing short of exceptional and highly beneficial to you, dear reader. My unwavering aim is to provide valuable insights and knowledge that will be of utmost advantage to all FK8 owners who are fervently passionate about improving the performance of their cherished vehicles. If you have any questions, comments, hate, or just want to say hi. Please feel free to reach out to me via Instagram @Functiontheory, Email Billy@Functiontheory.com, or simply comment on the post below and I will get back to you.