Another easy mod a novice can do.

Estimated time: 1 hour

Requires simple tools:
-car jack, jack stands (probably WAY easier with car lift)
-5/32 allen wrench
-13mm socket
-flathead
-philips
-pliers
-scissors that can cut plastic


1)jack the Fit up. the higher you go, more space you have to work with.


2)
Removal of stock underpanel.
there are 8 plastic lock tabs and 2 philips screws to remove the stock underpanel.




3) installing rear mounting hardware.
This requires 13mm socket to tighten the mounting hardware to the car frame.



The green arrow shows where the mounting plate that goes on the inside has to enter.


4) Installing Front mounts
There are two corner brackets and two skinny flat brackets for the middle.
Here is the location it has to go to get it inside to mount correctly.
Pliers were used to bend the flat bracket a little to get inbetween the radiator and the radiator shield thing (the metal part that is going to be sandwiched between the mounting plate and the underpanel)




When installing the underpanel, I removed a plastic lock nut (seen removed in the right of the picture) which holds the plastic molding that was blocking the corner hole.


The front middle mounting plates had a sharp bend in them which I flattened out with some pliers because the location where it is at is very tight. I bent them just enough so the tab can still stick out in order to be held when installing the panel.



5) Modifying the stock panel to keep the panel wings

In the other thread Wbd posted the wings of the stock panel should be kept. This is why..



Install tip: notice in the above picture how I used the rear mounting plates to hold up the underpanel. It makes installing the front bolts a lot easier when doing it by yourself.


I just used wirecutting scissors to cut where the yellow line is. it's the perfect spot to cut.




6) Mounting the underpanel to the rear hardware.

I had PMed gd3kamiwanaB the night before on why there was extra drilled holes seen at the rear of the underpanel. He said the USDM Fit is shorter, therefore required the extra drilled hole (used in the picture). The JDM Fit uses the unused hole in the picture.



7) Peel off the blue protective film! Finished!!




QUICK REVIEW:
- Looks awesome! (if you look)
- With aftermarket intake, engine noise is amplified and is noticeable after 2500rpm.
- It's mounted pretty secure so there isn't any rattling. Mounting hardware could have been simplified to be more convenient during oil changes.
- My crappy MPG was probably due to aggressive driving.. 70+mph highways. Going home today on a route I know I normally can get 35-36mpg on going 65mph, I got 41.1mpg going between 55-65mph drafting more than 70% of the time. This is probably the 2nd time i have ever reached over 40mpg since nov 07. The temperature shown in the scanguage is high because I just got home and parked and was trying to get a good picture. Normal Intake temp is 75F and water temp is 170F.

- I did notice I could coast a little longer than usual drafting behind big rigs.

- cornering stability at fast speeds: I've been trying to doubt this statement just because i thought it was a placebo effect. And probably because most of the time you'll never reach 'fast' speeds off the track. But the car does seem a lot more planted going faster than most people would want to go in curvy and hilly canyon passes. I asked my passengers if they felt body roll, they said no. I myself did feel a lot less body roll.

-stability: i suppose i can say the car does seem more 'planted' to the ground. I was on the 395 to mammoth mountain and there are some nasty crosswinds as well as on-coming traffic. The Fit didn't budge.

 

Great write-up!

I was kinda interested in this. Got this description of the product from a website. I Liked the 2nd bullet-item...:

 

Thanks man

yeah those three bullet points seem feasible. But for my current setup:

•Air turbulence is significantly reduced, producing a more stable ride at higher speeds and increasing down force by creating higher suction pressures between the panel and road.

I think the effect of this would be greater if my Fit was lowered.

•Engine temperatures are reduced and stabilized by removing heat from the engine compartment with specialized slits made to draw out hot air while the vehicle is in motion. This is successfully achieved during the creation of down force, as this negative pressure sucks out the heat and is then swooped out by colder air moving underneath.

I think this might actually work. I did notice my intake temperature was at 67F most of the way home tonight. Water temperature reading was 170F. I don't have any readings before intsalling it so I can't really tell if those are low numbers, but the intake temp reading seems pretty low (readings are from scanguage)

•Provides greater protection under the engine than stock plastic panels during heavy track or circuit racing competitions.

Even off the track, the underpanel covers a lot more area so it is protecting more of the engine from anything that could possibly fly under the car and bounce and hit the engine bay area from underneath. (Scroll up at the comparison picture)

 

Fantastic article! Much better than my "don't worry, you'll figure it out once you're under there" approach to how-to's. Great pictures too, including the very graphic view showing why it's a good idea to cut off the vertical pieces of the stock part and put them back on the car.

Now that I see how the factory hardware mounts to the car, I think I'm a lot happier with the setup I came up with. All of the mount points on my car are fixed in place and will not move. Plus I put those little screw-keeper-inner thingies on all of the mounting bolts. The end result is that I can slide under there, loosen all the bolts, and take the whole thing down as a single piece without worrying about keeping track of any little bits. Going back in is just as easy. I have done an oil change since installing the underpanel and it adds maybe 90 seconds to the whole process - in other words, it's a non-issue.

I noticed a little bit of extra noise in the passenger compartment as well, but it wasn't very much and I had pretty much forgotten about it until reading your post. People with headers and intakes may want to consider this particular aspect a bit more seriously, but then again they may actually like hearing the extra sound.

I'm still very happy with my decision to add the underpanel. I did it for fuel economy originally, but the added stability is my favorite reason by far now that I've lived with it for a while. It doesn't hurt that gas is under $1.50!

 

i think the engine compartment temps would be higher

 

Im going to get this after i get wheels/coilovers.

 

Maybe adding some RAAMat or Dynamat to the Beatrush Underpanel (side facing the engine) might help reduce some of the noise.

 

i think adding that mat thing would absorb the sounds, but then there would be insulation, which could definitely lead to more heat buildup. The engine bay is much louder to me because I have an aftermarket intake, if it was stock, then I'm thinking it wont be so noticeable.

 

A very thin piece, just enough to dampen 'boominess' that might come off the underpanel would probably work very nicely.

Underhood temps should be lower or, at worst, the same. At rest the underpanel will have little or no effect, and in motion the louvers in the panel will cause additional air to be drawn through the engine compartment. In addition, aluminum is a fabulous conductor of heat so it will draw some heat out of the engine compartment that way as well.

 

I know I'm dragging up an old post from the past but this seems to be the best walk through of install with pictures. I just came back from Japan and picked up my 2nd GD3 Fit that has been up for sale. As I'm going through making it mine I picked up the Beatrush Underpanel. Problem is the instructions are all in Japanese, and I can't read it. I found this thread the pictures aren't there anymore Does anyone still have the install pictures and could send them to me or knows of another spot to find them?
I searched Youtube couldn't find a video. Any help is appreciated in this!

 

I searched and found this:

https://www.fitfreak.net/forums/fit-...nderpanel.html

If you can’t find anything, I know they made a similar piece for EK hatches. Might be worth looking that up just to see. I’m sure they’re different but you might get some clues if nothing else.