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      06-15-2018, 08:59 PM   #1
AndyW
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Front Splitter update

UPDATE: Thread is now really about my journey to build a splitter so I changed the title. Original post below left for posterity.

So there are a number of threads on this but nothing going in the direction I want to go, which is a thicker splitter without rods, ala the M8 DTM (or similar). Anyone using a particularly strong splitter? I have looked at the OMG, APR, and Hard MotorSport options (among others)...all are great, but I think, too thin. I do have the front lip I mentioned in my previous thread:



And i know it produces some downforce because at the end of my last track day, the front left had pulled away from the tape, so I had to pull it off, retape, and add additional screws (was actually encouraging...and I am only up to 130 on the straight!). So now I want to add a slab to the front that could hold it's own without rods (I just don't like the rods...I have no other justification...but hey, BMW is doing it without rods on the M8 DTM so I can't be completely off the mark!)

Maybe I need to roll my own...and in that case...will take recommendations there as well!
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Last edited by AndyW; 08-03-2018 at 11:03 PM. Reason: Title change
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      06-18-2018, 02:59 PM   #2
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Comparing aero on a professionally built race car costing far more than most people's home isn't a good comparison to a street car with homebrewed aero mods.
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      06-18-2018, 07:21 PM   #3
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Quote:
Originally Posted by OkieSnuffBox View Post
Comparing aero on a professionally built race car costing far more than most people's home isn't a good comparison to a street car with homebrewed aero mods.
True...but it's a "how close for what cost" question. Apparently in the Miata world the answer is "Baltic Birch"...
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      06-21-2018, 01:15 AM   #4
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Splitters are usually made of a carbon honeycomb on top level cars like the M8 you reference. They are incredibly stiff for their weight and why they can get away with not using stanchions. If you tried to do the same size splitter with plywood it would either need to weigh a ton since it would be thick like crazy, or will bend to the point of not being effective. Stanchions are a good thing - embrace them.

-Mark
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      06-21-2018, 08:58 PM   #5
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Go with a custom cut out Alumalite splitter with a cheap air dam sandwiched between. Use the subframe as a mounting point for the lower splitter. My setup ran me ~$225 all in.
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      06-21-2018, 08:59 PM   #6
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The white pieces you see below the splitter are sacrificial delrin skid pucks to save my splitter from high G-force braking and long sweepers where the splitter would scrape.
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      06-22-2018, 06:50 PM   #7
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Spxxx...that is awesome, but you are so next level from me...lol.
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      07-08-2018, 10:41 AM   #8
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Spxxx, how many inches is your splitter? Looks like 3"? I made one out of 1/2 birch plywood that is 4" but it seems a bit much now that I have it on the car. It's good up to 70mph right now, so there is that...
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      07-09-2018, 11:59 AM   #9
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1/2" plywood!?! Damn that sounds thick, I bet it's damn sturdy too though...how much does it weigh and what did you mount it to?
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      07-10-2018, 08:03 AM   #10
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Quote:
Originally Posted by BimmerAg View Post
1/2" plywood!?! Damn that sounds thick, I bet it's damn sturdy too though...how much does it weigh and what did you mount it to?
It's not too bad. Apparently a lot of semi-pro racers use 1/2" birch...its where I got the idea.
The 4" version is about 9 lbs but I decided to cut it down to 3" so it is less now. I mounted it to the subframe and 4 points on the hard plastic "frame" behind the bumper. I did also mount the two "wing" outside points to the bumper cover but am using nylon nuts there so if something bad happens it shouldn't take the whole bumper cover with it. I'll post pics when I get finished, including the mounting points..
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      07-11-2018, 03:02 AM   #11
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Quote:
Originally Posted by AndyW View Post
Spxxx, how many inches is your splitter? Looks like 3"? I made one out of 1/2 birch plywood that is 4" but it seems a bit much now that I have it on the car. It's good up to 70mph right now, so there is that...
Just about 3 inches, little less.

The supports are overly aggressive but I'm done considering splitters wear and tear items lol
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      07-13-2018, 02:07 AM   #12
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OK, here's some pics of my splitter...gonna be testing it tomorrow so wish me luck!

Here is the subframe bracket design. I used two.



Here are the mods I made to the undertray with a dremel.



Here are the front mounts. One set through the front plastic frame and two support brackets I bent into shape and attached to a pre-existing bolt.









Here are two pics of the underside, showing the boltup points. Splitter bolts to the aluminum brackets, aluminum brackets bolt to the car with bolts that go through the splitter as well. 8 mount points total to car, 6 mount points splitter to aluminum supports.





Here is the splitter after one coat of spar urethane and one coat of gloss black.



Installed with rubber dam screw points revealed. Honestly, I am not sure if this aspect is going to work. But i had the rubber piece and decided to try it.



Front view.



Side view.



Ready for track day!

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      07-14-2018, 03:03 PM   #13
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I am happy to report that Track Day went great...no drama. Splitter stayed in place fine. Didn't really notice if the car was more planted or not on the straight (got to over 130MPH) but I was really doing this for margin and to balance with the diffuser vice gains. Rubber strip needs to be moved back about 1/2". One 4" section kept popping out. I had a camera pointed at the splitter for the first couple sessions and will review the footage today to see how much deflection I had. Foam rub strips were unnecessary...until I get a sportier suspension (and I am happy with the M-sport suspension currently) that lowers the car, I think this will be fine.
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      07-21-2018, 09:08 AM   #14
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Thought I would throw my hat in the ring. Mine is made out of 1/4 inch plywood and mounts to the bumper and the rear skid plate mounts. I haven't tested it on the track yet since the cheap struts I bought broke... Its painted black with truck bed liner and is actually pretty stiff. I can actually stand on it and I weigh about 160lbs. I am going to use it as a template for alumalite sometime in the near future.


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      07-24-2018, 01:29 PM   #15
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Good podcast with James Houghton/Chris Boersma and Mike Lewin from Professional Awesome. Towards the end, Mike Lewin talks (high level) about front splitters and air dams. Great rules of thumb.

Link: http://podcast.timewithattackers.com...pisode-03-2017

Also, some photos of Devin's S2K from Professional Awesome.
Link 1:

Link 2: https://www.instagram.com/p/Blk6Yy-l...roawesomedevin
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      08-03-2018, 10:57 PM   #16
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Update: Converted the mounting to 1/4 turn fasteners (dzus) for quick on and off and flatter profile. Pics below.



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      08-03-2018, 11:01 PM   #17
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Here's a good profile shot showing the splitter and difusser with the left side of the car under load, from a track day last month. Getting close to needing a stiffer suspension, I suppose!

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      08-04-2018, 01:49 AM   #18
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Quote:
Originally Posted by xBlueStreakx View Post
Good podcast with James Houghton/Chris Boersma and Mike Lewin from Professional Awesome. Towards the end, Mike Lewin talks (high level) about front splitters and air dams. Great rules of thumb.

Link: http://podcast.timewithattackers.com/138048/609821-time-with-attackers-episode-03-2017

Also, some photos of Devin's S2K from Professional Awesome.
Link 1: https://www.instagram.com/p/Bi5fcyAFwlU/?taken-by=proawesomedevin

Link 2: https://www.instagram.com/p/Blk6Yy-lXDz/?taken-by=proawesomedevin
Love these podcasts.

Splitter looks good OP!
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      08-23-2018, 12:06 PM   #19
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Quote:
Originally Posted by JCip91 View Post
Thought I would throw my hat in the ring. Mine is made out of 1/4 inch plywood and mounts to the bumper and the rear skid plate mounts. I haven't tested it on the track yet since the cheap struts I bought broke... Its painted black with truck bed liner and is actually pretty stiff. I can actually stand on it and I weigh about 160lbs. I am going to use it as a template for alumalite sometime in the near future.


wow that looks great!!! Badass!

What's the small lip you have? (not the 1/4" splitter part)
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