Splitters and air dams

[Andy Bettencourt]

We have developed a product for RX-7's, but we did it with a primary goal of managing cooling. It does a good job smoothing out the air around the front tires but we have no data on downforce, etc.

http://www.flatout-motorsports.com/catalog/images/105_0524.JPG

I would love to have people post pics of their solutions. We are about to develop a Miata solution but the difference is that it's primary fuction will be aero. Any hints, hits/misses would be great - not car specific, just trying to collect some data and opinions.

Thanks!

AB

[Greg Amy]

Something interesting to read... (see attachment). - GA

[charrbq]

Wow! Good article! All I could add was that a splitter on my air dam increased the turn in so much that I had to soften my rear shocks to compensate for the abrupt rotation in a sweeper.

[Joe Camilleri]

Here's one on the classic Mk1 Scirocco spoiler.[attachmentid=267]

[Bildon]

OK that's enough of that Greg! Don't be showing everyone where to get real information!
:bash_1_: :D

2000 Splitter
http://www.bildon.com/pub/PIC00296.JPG

With a little lift of the tail to diffuse B)
http://www.bildon.com/pub/turnbuckle.jpg

[flaboy]

wow...is that it legal??and if so where can i get something like that for my rabitt?


Tim

[lateapex911]

Sure it's legal, as long as it fits the plan profile and stops in the proper place.

And its strong too! look at it hold up the car! ;)

Where to get?? Looks like Lowes? Or is it HD? ;) LOL....

[tom91ita]

is there any concensus on the proper material of construction?

plastic? aluminum? paneling? masonite?

what thickness?

tia, tom

[MMiskoe]

I've been running a a similar set up to the Bildon model on my Nissan for a while now. Made out of 1/4" thick plywood. The thought process was on mtl selection was that it is cheap, easy to come by, easily formed and if it were to get demolished it won't splinter into parts sharp enough to cut down a tire (at least I don't think it is sharp enough to do that, haven't tried it). The best reason I came up w/ was seeing Trans-am cars, Formula Atlantics and Grand-Am style endurance cars all using plywood. I figured if its good enough for them, it ought to hold up for an IT car.

As far as the down force generated - yes it is noticable. The front feels much more connected and secure while going over hill crests (NHIS turn 8) w/ it on. As far as how much force - it being 1/4" plywood about 14" front to back and supported about 24-30" apart in front (either side of the radiator) I've witnessed 3 to 4" of deflection. When I'm trying to re-create that in the shop w/ my hand I am amazed how hard I have to push.

Similar to the way a Trans-am car is set up, mine is hinged at the back so I can raise it & tie it up for loading on /off the trailer. I secure it at the right height so it won't flap while on track.

[bldn10]

Matt, I remember the first time I saw a splitter on an IT car - it was the famous 70 SpeedSource RX-7 at the ARRC back in the 90s. I went over and scoped it out and was amazed to see that it was made of wood. Years later I buy a used SS car and the splitter is demolished at Barber in 7/04. Then I discovered that the "dive plane" is not your typical Lowes/HD plywood - it is Jabrock, some kind of high pressure-treated, impregnated plywood that is hard as nails. That is what is used for splitters, skid plates, etc. on pro cars. I looked into getting some and found that it was like $300 for a piece smaller than standard 4 x 8 plywood. So much for that. I made one out of 1/4-5/16" BC plywood and it looks good and has held up well over a season and a half. Do not use crappy CDX plywood - the leading edge will splinter. Or, as I did on a previous car, slit some fuel hose lengthwise and staple it over the leading edge as a bumper guard. It protected the edge and looked pretty cool too.

Can you explain your hinge in more detail? What secures the splitter in front?

[Greg Amy]

...I remember the first time I saw a splitter on an IT car...[/b]
Me, too. It was on Tom Blaney's CRX about 3 years ago; he had it in the bed of his pickup truck about to leave. I remember looking at it and thinking to myself "that cheatin' sonova..." Then I went home and read the rules, and recognized he was RIGHT!

I was never particularly convinced of the value of a splitter on our cars (the airdam was obvious), but I've gotten enough positive first-hand accounts such that I'm fabricating one now for my car. We'll see, eh?

[Bildon]

3 years? You haven't been paying attn. :P People have been running these for a long time in IT. :023:
Another nice bit to exploit is your fuel line guard. D.1.b
It can be WIDE and flat and run the length of the car. Also if needed it can be very heavy. B)

[JamesB]

Makes me wish my golf wasnt a small bumper car.

[Greg Amy]

3 years? You haven't been paying attn. :P[/b]
True, to a degree. I raced IT from '84-ish to '88, switched to SS for '89-92, then quit racing altogether. Rejoined SCCA '00-ish, hit the track again for the first time 2002. By then the IT rules had devolved from fairly straightforward street mods into the orgasmic broiling flaming pit of Satanic loopholes... B)

[RX-Heven]

LOL, that is a replica of a Demonspeed splitter for a 2nd gen RX-7 that I and others have been running for several years now.

However, it is good to know that there is an alternative to the pricks at Demonspeed as they are thieving cocksuckers.

That splitter made a huge difference in cooling, especially with my fmic since I was able to direct fresh air to the radiator below the ic. It is all boxed in and sealed with aluminum behind the spltter too.

There are pics in my sig.

[shwah]

If you take your time you can come up with a design that has a lot of horizontal area within the legal envelope on a small bumper or no bumper car. Mathis has a pretty good setup on the front of his car that certainly looks IT legal to me, as long as you set it with the lowest peice even or above the bottom of your wheel rim. We do have molds, might be able to talk Rob in to making some for sale.

Crap - forgot about the BS slow upload connection here at work. I will have to put some pictures up tonight.

If you take your time you can come up with a design that has a lot of horizontal area within the legal envelope. Mathis has a pretty good setup on the front of his car that certainly looks IT legal to me, as long as you set it with the lowest peice even or above the bottom of your wheel rim.

[MMiskoe]

[attachmentid=277]
Didn't know that about the plywood, had I konwn, I would have still done what I did. I did use the higher grade stuff & for its cost & the amount of abuse it has taken I cannot complain. The original intent had been to get more air into the radiator instead of having it just go under the car.

This is the best picture I have of it. The car has a pan between frame rails, below the radiator, but set back quite a ways back from where the bottom of the bumper cover ends. The hinges are attached to that pan so they are a good 10-12" behind the bumper cover. The plywood ends at this pan, the hinges attach to the back edge of the plywood. Since the bumper cover sticks out further, the plywood follows that contour and leads the bottom of the bumper cover. Up inside the bumper cover are mounts for fog lights w/ nicely placed threaded studs. A small pc of aluminum angle iron (horizontile) bolted to the studs recieves a pc of threaded rod (vertical). The threaded rod has nuts top & bottom that can be adjusted to raise or lower the leading edge. At the end of the day, they get backed off and it gets raised so it hits the bumper cover bottom edge and clears my trailer ramps.

My biggest problem with it seems to be stepping on it while working/walking around the car.

[seamus88]

[attachmentid=278][attachmentid=279]Here are pictures of mine. I made a drawing in CAD and had my friend waterjet the aluminum. The one in the picture has been repaired twice.So the original pop rivet tabs are missing.You can see the little "L" brackets I used in there place.The duct work is just standard gutter drain parts that connect to sump pump hoses attached to the car.I have to take it off to tie down the car.

[bldn10]

"Another nice bit to exploit is your fuel line guard. D.1.b
It can be WIDE and flat and run the length of the car. Also if needed it can be very heavy."

:o Whoa, Bill, are you suggesting what I think you are? A flat piece of metal attached to the underside protecting the fuel line but also acting as an undertray?

I just do not read that rule to allow that. All it says is that the fuel line may be "given additional protection." It then goes on to talk about metal or metal braided lines through the passenger compartment. I think all it means is that you can use metal or metal braided lines or otherwise wrap the lines in some kind of protective sleeve - not weld or bolt some piece of metal to the chassis. Has anyone actually done this? I like the idea; I just don't think it will pass muster.

[shwah]

A metal plate bolted to the bottom of the car is 'additional protection'. However a metal plat along the whole bottom of the car for this purpose would fall under the allowed modification performing a not allowed function. Otherwise it is a smart interpretation of the rule IMO.

[charrbq]

I bought an airdam/splitter for my Honda when I first started racing it. The thing was a beautiful piece of engineering and worked great on my car. It was made of quality material so it wasn't cheap.
The first race, a SM missed a shift, spun, I spun avoiding him and went off track. As I drove back on course, I saw my very expensive, well made, now rumpled and crushed air dam lying on the ground.
Since then, I've been making them out of ABS. It's strong, flexible, easy to work with and modify, takes abuse, can be repaired, and looks pretty good...not as good as the metal one, but not bad.
Every once in a while it gets well good and screwed, but I just get out the jig saw and heat gun and make another one.

[p99ro]

Hi
I need one for a 89 CRX. I too dragged mine on the track then melted the plastic on the pipes. I drove over it even before I mounted it :bash_1_: . I need one that can be remove to put the car on the trailer. So if anybody has any Idea`s let me know. I had a Blaney nose it worked fine but I`m not sure what good the d. NASCAR guys say they need to go over 125mph before anything happens. But I have stuck my had out the window and it has a lot of force so what do they know.
Scott CRXsi 07 NER and board. It`s so nice in CT wish LRP would do a track day. Somebody`s must be on that track.

[paulydee]

Sorry I am chiming in late on the subject. I have been off the forum for a while. I decided on an aluminum solution to the splitter option. I have some good pics of the work up here:

http://www.iridiumracing.com/NewMods.htm

It is kind of nice to have the metal because when I have an off road excursion, it generally just needs a little massaging to get it back in place.

[Jiveslug]

Ok guys, so this talk about splitters got my curiosity going and I decided to take a few measurements and see what I could come up with for my Corolla. Looking at the front of my car, I realized that it would probably be best to build the splitter and air dam as one unit. No one makes decent air dams for the TE72 Corollas. ANYway, as of right now, the car has a ride height of 10.5” at the rocker panel. Granted, this is with the stock suspension, stripped interior, and half the motor out. Anyway, I can basically drop the car 5.5” from its current height and be legal. Lets round that to 5” to be safe. Ok, so the lowest hanging section of the front end is the tiny valence that just pokes down below the bumper. It’s 13.5” off the ground as of now. Thus, if I drop the car 5”, it will be at 8.5” from the pavement. Cool. Subtract another 5” from the 8.5” to stay within legal ground clearance, and I have 3.5” of empty space under the valence that I can fill. I then looked for the best theoretical mounting point for the air dam, which just happens to be right below where the valence mounts to the car. I measured from that spot to the ground and got another 2”. Ok, so it looks like the air dam can be a total of 5.5” tall if I use that mounting point (the air dam will cover most of the valence). Ok, now, I had to guesstimate (didn’t feel like removing the bumper) how far out the bodyline of the car went. I measured the distance forward from the air dam location to that point and came up with 3.5”. Thus, if the air dam is perfectly perpendicular to the ground, that leaves me all 3.5” to utilize in building a splitter. If the valence is 56” wide, then I’m looking at an assembly that is 56” wide (duh!), by 5.5” tall, with a 3.5” splitter.

Ok, here come the questions.

1. How far around the side of the car can the airdam go? I have about 7.5” before I hit the front of the wheel well. Can I go that far back?
2. I was thinking of putting hinges on the front of the airdam so it can swing toward the front of the car and up in a 90 degree arc for transport. Is that legal?
3. Anyone have any general thoughts to this design?

I’m going to have to make final measurements and whatnot, and of course I’m going to make sure to have the 3” holes for brake ducts. What do you guys think so far?

[dickita15]

Your air dam can be lower than 5 inches. What limits it is17.1.4.D.8.c “

No part of the car, except the exhaust and suspension components, shall be lower than the lowest part of the wheel rims”

The test is to measure from the ground to the bottom of the wheel and make sure that air dam does not hang below that. This will be different depending on what profile tires you run. When I went to 45 series it allow more air dam.

To be honest you can start working on the design now but if you want to go as low as possible you will not be able to finalize that until you have the race tires on and the ride height set.

[benracin]

Do you think this would be more bad then good on a car that's a bit rear end happy like a first gen rx7? I know that they sure do look cool!

[Andy Bettencourt]

Do you think this would be more bad then good on a car that's a bit rear end happy like a first gen rx7? I know that they sure do look cool! [/b]

Depends on when and why your car is loose.

[lateapex911]

here's my rather generic version.

[bldn10]

If you are thinking of going lower than you are now and/or extending a splitter its max allowed distance forward, you MUST take into consideration the effect on getting the car on and off your trailer. Unless it is easily removable, you will be amazed at the reduced slope that will now be required.

[JLawton]

Also remember those spots on the track where your suspension gets compressed big time. In my 944, it was the done hill at Lime Rock. Between cornering and hitting the bottom of the hill, my extended spoiler would scrape the track. It was sheet metal so I would just pound it back.