looks legit

 

Just thought I'd update this thread and mention that I'd currently still using the 11/32"-thick plywood splitter. It's done well over 100 miles on the track now, not to mention about a full season of autocross, and it's scraped the ground pretty hard many times... still holding up great.

I did recently add a a couple reinforcements to the two middle support brackets, however.

During one track event last fall, where I scraped the splitter pretty hard experimenting with a lower setting, the splitter got shoved partially under the front bumper cover, despite the ABS plastic air dam that would discourage rearward movement (of course it's not strong enough to resist a big hit).

I realized that I needed to not only "suspend" the splitter downwards from the bottom of the car, but provide a modicum of strength/resistance to the backwards force upon the splitter when it hits the ground at speed.

This is the idea I came up with... wanting to minimize weight, and working within the limitations of not really having any decent additional mounting points under the nose of the car that are at the same level... if I did, I would have likely have built some kind of large rectangular framework out of square aluminum "piping," although that would have been fairly expensive in terms of additional materials required, and complex or impossible to maintain my height adjustability.

These are just the steel straps I originally used to use as the main, front-facing splitter supports, repurposed. The idea was to create a triangle bracket, where the short, vertical leg is the existing bracket to the bottom of the car; the longer, horizontal leg is the splitter itself; and the longest, hypotenuse comprised of the strap.

Since the strap's two ends are fixed (mounted to the same bolt as the vertical support, and tethered to the plywood splitter via a standard metric 6mm bolt and U-type speed nut), in theory, in order for the splitter to be pushed backwards more than a few millimeters (due to the inherent flex and stretch of all the materials) that metal strap will have to either rip out of either end point, or stretch (physically deform permanently), or break catastrophically (i.e., tear in half).

I realize this isn't going to an 100% effective solution... maybe in the real world, it will be at best 65% effective, to minimize backwards movement of the splitter, for impacts of fairly minor force. I don't expect these thin little steel straps to keep the splitter from being rammed back into the front tires if I were to catch a curb on track with it at 65mph, for example.

But by the incredibly un-scientific test method of attempting to push back on the leading edge of the splitter with these two brackets in place (I really should do all four mounting points) I can feel a lot more resistance/"firmness" than before.

The view of the driver's side support strap, from the middle of the car:



Same strap, more from behind it:



Below are the most recent pictures of the car with the splitter. You'll see that I've also added three small aluminum "winglets" to the leading edges of the splitter that are intended to keep the splitter from catching on a hard edge, like an entrance to a parking lot (I drive the car with the splitter attached to autocross and track events) or a nasty, uneven crack in the pavement running across the course at an autocross event.

The intention was to unscrew/remove those three "safety-margin-for-street-use" winglets once I got to the race event, but in reality I'm too lazy to remove and reinstall them, so I've just left them in place... I'm assuming the two towards the sides of the car are reducing the effectiveness of the splitter a little by disrupting airflow, but I can't say I can feel their negative effect:

PHOTO BY TODD BRILEY

 

so the splitter SHOULD be angled upward? seems odd. i'm assuming this was covered.. but reading from work/cell and i can't really load all the pages that well. sorry.

 

i wish the pics worked!!!

 

To simplify, having the splitter as close to perfectly parallel with the ground surface should work best. When I went to "version 2.0" splitter supports, I built turnbuckles from threaded rod and spherical ball joint rod ends in order to provide easy adjustment of the splitter angle.

So, this 10GB bandwidth limitation imposed by Photobucket's free account has become a problem.

I'll try to get around to moving the images to another hosting site, but in the meantime, you should be able to view all the pictures I took of my splitter and the DIY project by going directly to the Photobucket album (click the link below):

http://smg.photobucket.com/user/Hsun...?sort=3&page=1

There are a LOT of pictures in that album, so you'll have to scroll through all seven pages to find what you're looking for.

I should mention that back in the late summer of 2013, I had a custom carbon-fiber splitter made in the same shape/dimensions as the plywood ones... mostly because I wanted to see what the weight savings would be, compared to the 11/32"-thick plywood splitter.

The CF splitter is extremely minimalist in structure—its total thickness is only 3/16" thick. I sacrificed stiffness by not using a fairly thick (1/4" is typical) foam reinforcement layer inside the outer layers of CF cloth in the hopes of reducing the total weight of the splitter blade.

So how much weight did I save by spending $$$ on a carbon splitter instead of going the Home Depot plywood route?

The answer: basically, NONE.

The CF splitter weighs 10.9 pounds to the 11.18 pounds of the 11/32" plywood splitter... barely a quarter pound weight savings. The primary benefits of the CF material are not in weight savings, but:

1. It is 100% waterproof. With enough repeated exposures to heat and water, my urethane-coated plywood splitter was beginning to warp a little.

2. It is somewhat stiffer than the 11/32" plywood (but not anywhere near stiff enough to where you could eliminate the support rods and save that hardware weight and eliminate the aerodynamic turbulence the supports cause).

3. Because the CF splitter is thinner, it should be marginally better at cutting into the airflow and directing air over the car, plus a tiny bit of ground clearance is gained.

4. It looks cooler.

5. People who see you have a CF splitter on the car might think you're a baller, when in reality you have five-figure credit card balance because of your stupid Evo race car.

 

does this thread mention what you use as a dam between the lip and spliters? I didn't see anything.

 

Very first item on the V2.0 parts list on page 3 here:

You don't need nearly that much material to make a skinny little 3"-tall strip of course, but I didn't want the air dam to have a seam in it, so I needed a full 4' x 8' sheet to achieve that.

 

I really like the carbon splitter, have you considered doing carbon canards? I know voltex makes them, but I am sure they could be built cheaper. They would complete the look, but I wouldn't know how much weight savings you would get.

 

Gracias. I was thinking it was something simple like that.

 

Why wood?

 

Because cheap.

 

bumping this thread because its a great resource and i'm going to be making my splitter soon.

Have you given any thought to quick release hardware to mount the splitter? Driving around with a huge splitter on a lowered evo isn't always ideal, and probably discouraged on my 250 mile treks to local tracks.

 

Inspired by this thread I have started my own for my autox evo. I shall update as it progresses.

 

I have all the parts to build mine, but have been busy. A quick release setup would be helpful....I can't drive around town with it on.
I haven't figured out how to transport it to the track, either.

 

I did quick release hardware on the rods, then the frame is just 7 bolts. Pretty easy to get off once the front end is in the air.