Custom Undertrays
 

Ok, some shit flew up and smacked my motor, and I've driven over enough shyte that I'm enlisting the help of some people here to make a custom under tray for my Evo VIII. Mark (TKRPerformance) says he can cut the metal after we get the templates laid out, and he wants one for his own car (Evo3), so it seems like we can get it done together. I know hughes wants one of these for his Evo IX, so we'll prolly end up doing one for his car too. I'm thinking we'll keep the templates and help out other locals if this goes well. If it falls to shit, then let this serve as a guide on what not to do.

Ok, so first things first, what do we want? Something to cover the bottom of the motor compartment. Why? Two reasons. One: aerodynamics. Any car can benefit from an undertray, the farther it goes back, the better. All high-end sports cars have full belly-pans that cover the entire bottom of the car. Two: protection. One cool thing that I have noticed about the my evo is that it has a lot of extra protection in the form of shielding covering the oil pan, the starter, and the bottom of the tranny. This must come from years of rally experience. Still, it was not enough for my car.

Design: SIMPLE. I want this to be as simple as possible. Buschur is making some cheap ones that basically tuck under the front lip around the entire front of the car, go back to the front of the wheel wells, around the wheel wells, and all the way back past the back of the engine compartment. I want one big solid sheet, and possibly some access panels for the front tow hook and the oil filter.

Materials: several people suggested Discount Steel down on washington, I'll hit them up and see what they got.

Fasteners: I'm eyeing these DZUS/Panex fasteners as seen here and here. These are 1/4 turn quick-release aircraft quality fasteners with D-hooks on the back so you can remove it with your fingers.

I'm open to suggestions, tips, or even if anyone wants to help, let me know. I happen to have a big-ass piece of cardboard in my garage right now for the design of this thing.

Re: Custom Undertrays
 

I would like one for my car.

Re: Custom Undertrays
 

I want one! I would think aluminum or plastic would be the best material since it won't retain heat and be lighter than steel.

Re: Custom Undertrays
 

someone suggested acrylic, I'm gonna see what we can get for how much. I'm thinking aluminum will be the way to go, as it won't be too spensive and will be pretty tough.

Re: Custom Undertrays
 

I just did some searching online and given the prices I think you should stick with something metal.

Re: Custom Undertrays
 

Acrylic is pretty brittle, but UHMW works great. Here is a 4'x8' sheet at Grainger. Should be enough for 2 of them.

http://www.grainger.com/Grainger/items/1UWG4

They also have polypropylene much cheaper and I think it would have the flexibility, but I am not as sure.

http://www.grainger.com/Grainger/items/1YYC2

This looks like a good possibility too, but I don't know anything about it.

http://www.grainger.com/Grainger/items/1ZAT5

Re: Custom Undertrays
 

I think black or grey would be a little more appealing. ;)

Re: Custom Undertrays
 

I want a green one.

I was thinking a big sheet of tag-board would work great for making the template. Its cheap, easy to get, thin, and flexible.

Re: Custom Undertrays
 

I personally used some sheet aluminum on the one I built. Mine isn't a complete undertray though, it's just mainly used to trap air so that it has to go through the radiator. I don't remember the thickness, but it was pretty thin. I got it from Lowe's. Discount Steel would have been a better bet, but Lowe's was 2 minutes from my house.

Re: Custom Undertrays
 

i personally dont have a need for an undertray, but im really curious to see how this works out for you guys. good luck and keep this thread updated.

let me know if you guys need an extra hand.

Re: Custom Undertrays
 

Hughes I like the tagboard idea, any idea where we could get some big enough but cheap enough?

Re: Custom Undertrays
 

I used cardboard to make my templates. Derek used cardboard to make his as well. Worked pretty well for us.

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The sheet I want to make is pretty big, I'm just worried the cardboard will flex a little too much. I'll give it a try.

Re: Custom Undertrays
 

Walmart, we can tape a few together.

Re: Custom Undertrays
 

Fuck walmart.

Re: Custom Undertrays
 

Fine, go to Target and spend more :)

Re: Custom Undertrays
 

I'm thinking we could use some 1" x 1/8" straps to fab up a piece like this. The stock undertray has a part of it like this, it bolts to the center crossmember and then hangs down a bit to offer support for the tray in the middle:

http://i228.photobucket.com/albums/e...d_IMG_2122.jpg

That way its not flappy in the center.

Re: Custom Undertrays
 

I have big pieces of cardboard here from all the parts coming on pallets all the time. just use that and some zip ties to hold it up. sense you have the stock tray still we will start with that and make it go all the way back. It will not be to hard to make them

Re: Custom Undertrays
 

I've been thinking about making one for my car as well. I'll probably use 1/8" aluminum sheet with Dzus fasteners for a little extra strength. I want to keep my nose from buckling in at high speeds since I'm planning on trying a standing mile competition this year.

Re: Custom Undertrays
 

Will over-heating be an issue if one is implemented?

Re: Custom Undertrays
 

it should not be a problem sense we are just going to make alum ones to replace the oem plactic ones

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Ya these cars come with hood vents, so there's plenty of places for the air to go once it comes through the IC and/or radiator.

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My bad, didn't know they came with plastic ones.

Re: Custom Undertrays
 

Heh I was going to call discount steel for a quote, but guess what, their stuff is available online!

I need advice, they have 5052 aluminum sheet:
http://www.discountsteel.com/index.c.../itemID/83.htm

or 6061 aluminum:
http://www.discountsteel.com/index.c.../itemID/84.htm

I did some measuring:
http://www.scheides.com/gallery/evoundertray

and I figured out that I need about a 63" x 38" sheet.

The above links will give me a price, but the size is listed in .032-.190, is this supposed to be like .032 inches, or is it a gauge or some sort? .125 in the dimensions I want is going to be like $90 for a single sheet of the 5052, doesn't this seem a little expensive? I don't mind spending this much, just want to be sure I'm getting the right thing.

The site says they also offer precision cutting, I might hit them up and see how much that'd be....would be a nice way to reproduce this for other evo owners....

Re: Custom Undertrays
 

.032 is 1/32 in
.125 is 1/8 in
.190 is 3/16 in

6061 is aircraft grade alum.
alum is not that cheap to start with. could always go with steel and have them power coated

Re: Custom Undertrays
 

Overheating probably wouldn't be an issue, but it wouldn't be hard to make some louvers in it to pull some heat out the bottom. As far as using some type of plastic goes, I'm not sure if that would be such a good idea. You have to remember that the down pipe would be right next to it, and of the ones that Jet listed there, the highest max temperature rating was only 210*. Also, the one that listed an impact rating was only 1.3 pounds. As far as template material, I would suggest cardboard. I can get pieces more than big enough from my shop from the boxes we get parts in. To me, tag board would be a little too flimsy to work with.

Re: Custom Undertrays
 

We sell those 1/4 turn bolts at my volkswagen dealership (they go in passat bellypans and they dont have the little handles) and we sell those speed nuts too. so i guess if you need a replacement or somthing you know where to get them without waiting.

Re: Custom Undertrays
 

1/8" aluminum is going to be pretty flimsy on a piece that big. I would look at the 3/16". I really love the UHMW, it takes a serious beating. Aluminum will work well too and be slightly lighter, but will dent.

Re: Custom Undertrays
 

This is really ghey.

To get a sheet of aluminum the size I need, the metal alone is going to cost me $180+ and if I screw it up, too bad (sorta).

To get a thinner sheet of stainless steel (heavier, but stronger), I would go with like a 12ga (1/10") sheet.....~$300 :(

Anyone have any other ideas? Otherwise, if the price is right, Buschur is selling a pre-cut, pre-measured undertray for $175+shipping, no muss no fuss.

Re: Custom Undertrays
 

Also, looks like I can get regular steel for $70, but doing the math, it's going to weigh 60 pounds! Geebuz....

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No ABS plastic sheets? I think Polypropylene would be good, I have some speakers that use that for the cone, it seems to me it would be a great material for an underbelly tray.

The thing is, even if you had a metal tray, if you hit something that is oblong and "tumbling" down the road, depending on its solidity, mass, it would punch a hole right through thin metal. It seems to me that the greater purpose this tray would serve is for aerodynamics, plus shielding from smaller stones and things of that nature, rather than the huge, random piece of flying debris that you hit.

I also want to get one of these, but that plastic or poly sheet from grainger posted above looks perfect for me.

Re: Custom Undertrays
 

ABS won't work at all, it is way too brittle. Polypro is a possibility, but is pretty stiff and brittle also. UHMW is not brittle and takes a lot of abrasion. I am sure Buschur's are plastic and probably pretty brittle in the cold weather (most cheap plastic is), down south you could get away with a lot more.

Re: Custom Undertrays
 

I wouldn't want to use a plastic undertray in any case, considering the close proximity to the down pipe. Unless it was something proven to be resistant to the heat.

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Just do a little cut away for the DP. Worst case scenario is that it would droop down a bit in that area, but I doubt it. Wrap it and it would definitely be fine.

Re: Custom Undertrays
 

Ok, I finally FINALLY got this done! I was going to order the buschur undertray at $175, but UPS got sick of shipping them for a 'mere' $75 and upped shipping charges to freaking $200. So, I decided to just get the beatrush undertray and get it done. In the end, I'm SUPER happy with it. MAP got me a killer deal on it, and with some minor modification I got 2 bags of dzus fasteners from kurveygirl.com to fit nicely. These are nice 1/4 turn fasteners used on airplanes, motorcycles, and now evos :)

Oil change = 4 fasteners
Tow hook = 4 fasteners
Whole tray drop = ~10 fasteners

http://www.scheides.com/albums/evo-u...9252.sized.jpg


http://www.scheides.com/albums/evo-u...9253.sized.jpg


http://www.scheides.com/albums/evo-u...9254.sized.jpg

Drilled out the holes for this panel for the new fasteners:
http://www.scheides.com/albums/evo-u...9255.sized.jpg

Aero veins mounted:
http://www.scheides.com/albums/evo-u...9257.sized.jpg

Fully installed!
http://www.scheides.com/albums/evo-u...9264.sized.jpg

Just in time to use these puppies:
http://www.scheides.com/albums/evo-u...9267.sized.jpg

Bring on the snow :D :D :D :D

Re: Custom Undertrays
 

That is pretty slick! Nice!

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I'm very impressed with the undertray; definitely a great piece which I'll be getting once my stocker gets all busted up.

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Those looked pretty nice when they came in, glad to see some pics of them on and being put to good use

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Yah, you need to consider heat and airflow as well as water drainage.

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This is why the Beatrush is so far superior to Buschur's in my mind. Buschur's is great for a drag car since its smooth and extends so far rearward, but for a daily-driven street car its lacking in many regards.