Presented by Nine Lives Racing
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WonkoTheSane (Forum Supporter)
WonkoTheSane (Forum Supporter) SuperDork
5/8/20 1:39 p.m.

Back in January, I ordered a Nine Lives Racing Medium Downforce Kit for my 94-spec-miata-turned-track-car:

In between, there was a run on affordable aerodynamic products apparently, and some sort of pandemic (Covid?  I hardly knew her!), which meant that I didn't get my kit until about two weeks ago.

In the meantime, I've been meaning to head over to my friends' house to check out his new router, so making a splitter seemed like a good idea.

My initial opening shows that all of the components were packaged really well and they seem to be pretty high quality, especially around the wang.  As you got to the mouth end, there was a lot more ambiguity, the lack of instructions was a bit concerning, and the machining quality wasn't quite as nice/finished. 

Overall I'm quite happy with the kit at this point, but you can tell that you're not working with Flyin' Miata, Paco, or GoodWin on the instruction department.  That's not so much a knock against Nine Lives, but more a note that since I order a lot of stuff from FM, I've been pampered by the clarity of instructions :)

WonkoTheSane (Forum Supporter)
WonkoTheSane (Forum Supporter) SuperDork
5/8/20 1:47 p.m.

The first (and easist) part of the install was to install the new wang. 

I'm not going to rehash all the steps, as there's a great install guide listed on their website.  I followed that recipe with a few changes.  

My changes were to pull the rubber gasket off of the trunk lip and then cut little Vs into it so I could line up the drill easier and I didn't destroy the gasket:

Note that I didn't cut the Vs all the way down to the corner I left plenty of meat at the bottom to divert all but a solid wall of water.

Also I made sure to coat it all with Eastwood's Chassis Black so it doesn't rust. 

Finally, I kept the deck cut a whole lot closer to the wing, which looks a ton better, but took a lot more time and measurements:

WonkoTheSane (Forum Supporter)
WonkoTheSane (Forum Supporter) SuperDork
5/8/20 2:31 p.m.

Because I work for a CAM software company and a few of my coworkers have routers in their garage, I opted to just buy the dimensions to make a splitter from Nine Lives instead of buying one of theirs. 

For reference, here's what theirs looks like:

I got the PDF and I have to admit I was a bit let down here.  I was hoping for a DXF with all critical dimensions laid out, but I think as a guy who works in manufacturing, I had my hopes set a bit too high.  Here's what I got, note that I horribly, horribly compressed this and intentionally hid the two dimensions that were on it.. Buy it from them if you want pretty lines and the dimensions, ya mooches!: 

Obviously, there was a discrepancy between what they were selling as a complete splitter and what the PDF was intended to do.   

After badgering them with about 200 questions, I got the critical details I needed, here they are for posterity:

  • The splitter is made of 1/2" birch plywood (it cost me ~$63 from the local lumbar yard, NOT a box store)
  • The "X" pockets are for weight reduction, not critical dimensions, and they're 1/4" deep (1/2 of the thickness)
  • The Low Pressure pocket on the bottom of the back part is not a critical dimension, although larger is better as long as you don't damage structual integrity.  Also 1/4" deep.
  • The Damn Dam is .115" thick, so the slot needs to be at least that.  I made mine .2" with the intention of adding a bit of RTV.
  • The splitter is made in two pieces because you can get two splitters out of a single sheet if you do that.
  • The front edge of the splitter should ideally be a "bullet" style design, or at least a "bull nose" that's nicely tapered if possible.  This is not critical, but ya know, aero and stuff.
WonkoTheSane (Forum Supporter)
WonkoTheSane (Forum Supporter) SuperDork
5/8/20 3:07 p.m.

The good news is that the two given dimensions looked correct, and the PDF was scaled correctly, so nothing left to do but break out the crayons and markers and make it into:

Okay, okay, there was a bit more to it than that.  Because it wasn't a DXF, I had to run it through Inkscape to convert from a PDF to a DXF, and then scale it appropriately.  Scaling it was easy in our software (Mastercam).   Then I cleaned up some ugly noise that seemed to be induced by their output to PDF, finally I extruded the basic shape they gave me with drill holes.  After that, I split up the model like they do with theirs for shipping/material reasons, before finally doodle-ing up the pockets and extruded them down into the part.  Other than that, it was just nesting the two parts onto a 4x8' sheet.

Slap some toolpaths on, and it'll look like this when it's cut out: 

Time to head to my buddy's shop:

All that's left is to finish sand them and coat then with some truck bed liner..

WonkoTheSane (Forum Supporter)
WonkoTheSane (Forum Supporter) SuperDork
5/8/20 3:31 p.m.

We haven't had a nice day that I wasn't working, so I haven't gotten then splitters finished yet, but in the mean time I decided to get the front of the car off to install the mounts.

This is where the lack of instructions was definitely a hinderance.  Johnny said last month that they were working on getting them done, but in the mean time he helpfully released some youtube videos.   Watch these before you open the box, so you understand what the pieces are:



Basically, you want to end up with this:

And the side mount panels bolted here:

Note that there's a really nice "L" bracket spacer that goes behind the side mount panels to take up the gap caused by a fold in the factory metal.

I did have to find my own M6x1.00mm bolts, as there were only two in the hardware kit and you need 4.  Luckily I have plenty.

Note that the "sturdy boiis" that mount to the splitter need to have the receiver brackets mounted to the side mounts.   The video above sort of covers it, but it did take me some trial and error.  Here's what it looks like when properly assembled:

This is another instance where you can tell you're not quite dealing with FM, as a lot of the holes of the brackets were not punched all the way through, and the water-jetted receiver brackets needed to be snapped off.  I cleaned that all up with the bench grinder, as I don't like sharp bits under the car when I need to reach in to sort something out!


The only thing I ran into is the issue of spare parts.  I have no idea what these parts are for:

I just sent an email in this morning to Nine Lives, to see if they can point me in the right direction.

Other than that, I'm going to replace the nuts that came with the side mounts to be Nyloc nuts, as I don't trust the nuts that are there.

This quick-connect splitter connection looks awesome!   I can't wait to get the Damn Dam installed next!  ...  As soon as I figure out how :). I'm assuming it's just tack it in place using the included rivets after cutting the bumper away.  We'll see.

Rodan Dork
5/10/20 9:54 a.m.

Thanks for posting this!

Aero is the next big project for my NA, and I've been debating over DIY vs. 9LR...  I have a set of splitter brackets from TSE, a roll of plastic for the air dam, and the garden border material for mounting it to the splitter, but that's as far as I've gone.

My plan for the airdam was to use rivnuts for attachment to allow easy removal.

I really like the 9LR splitter, but it looks like the mounting setup will still require a lot of work to seal the ducting.

Watching with great interest...

WonkoTheSane (Forum Supporter)
WonkoTheSane (Forum Supporter) SuperDork
5/10/20 11:44 p.m.

Glad it's useful Rodan!

Yeah, I was a bit concerned about the gap, but I realized that it's already way better than the stock black plastic surround, and I haven't had any over heating problems, so I don't plan to do anything immediately about it.

I was also thinking about rivnuts for the dam, but honestly, anything that would require dam removal can probably just as easily be done with bumper removal, so I'm going to just rivet it.  It'll still pop off with the bumper.

I will say that all of the stuff from 9L seems really well thought out and pretty high quality.  

I just got my splitter sanded and glued together today, so I'll hopefully have an update for you soon if it's nice, then I can get it all finished up.

thatsnowinnebago (Forum Supporter)
thatsnowinnebago (Forum Supporter) UltraDork
5/11/20 3:07 p.m.

I gotta say, having that size of CNC router is pretty clutch. Your parts came out looking great. 

WonkoTheSane (Forum Supporter)
WonkoTheSane (Forum Supporter) SuperDork
5/11/20 5:41 p.m.

Thanks!  Yeah, it's a cool toy :) I'm lucky to work with people who have them and will let me play with them!


Small update:

I ended up getting the sanding done yesterday and putting the rounded nose on by hand.  I didn't do it on the CNC since I couldn't remember what size round over bits I had, so I didn't want a mismatch with his.  Also, we weren't going to do a second fixturing to do the underside anyway.

Then I glued it together and bolted it temporarily until I can get the proper hardware next time I venture out:

WonkoTheSane (Forum Supporter)
WonkoTheSane (Forum Supporter) SuperDork
5/11/20 8:31 p.m.

I'm thinking colonial maple for the leading edge will go nicely with the color of the car..  the rest will be coated in truck bed liner.

WonkoTheSane (Forum Supporter)
WonkoTheSane (Forum Supporter) SuperDork
5/16/20 10:06 p.m.

Today's update:


On Facebook, they got back to me and said that the two smaller plates shown above are for reinforcement plates for the locking bobbins, and the u-shaped bar is to go over the subframe to help lock it in place.. 

I'm not completely certain what they mean, though.  This would be a lot easier if they had instructions as none of these are shown on their YouTube channel videos.

I'm assuming that the reinforcement plates go like this:

WonkoTheSane (Forum Supporter)
WonkoTheSane (Forum Supporter) SuperDork
5/16/20 10:10 p.m.

I got my splitter finished:


However, I can't get it to mate to the car, as the back of the splitter is getting interferance from the steering rack mounts:

It also seems to long to have a bracket go above the rack.  Again, at even a picture of the bracket installed would be helpful..  it's not shown in a single picture, nor is there any holes for it on the splitter shown on their site.


Thinking about it, I flipped this piece over because I made it like they do on the website, but I did not flip the slots over.  But it's still too long.

WonkoTheSane (Forum Supporter)
WonkoTheSane (Forum Supporter) SuperDork
5/19/20 2:31 p.m.

After a bunch of cutting, and talking to a friend that purchased one of the first splitters from 9 Lives, it looks like the PDF is based on the first design of the splitter, because we both ended up cutting off about 1.75" @ the back to get it to fit and doing a bunch of other cutting to fit it.

The slots are a bit to small even after inverting, and if you get the PDF note that the whole thing is the "bottom" and the slot for the air dam should be on the "top", basically, if you get it, you'd have to cut it out following the outline, flip it over, cut the slot for the dam (or add your brackets), but the back profile will still be off.   

Here's what mine was off in reality:

If you assume the PDF is supposed to be the top view (i.e, the one the dam slot is cut into), then here's the difference in the rear profile:

So yeah, I'm still not sure the PDF didn't cause me more problems, but I'm erring on the side that it was worth the $10, but not any more than that!


With that said, I'd like to open-source my derivative work.  Feel free to send me an email with proof that you bought the PDF from 9LR, and I'll give you a DXF or PDF of the rear profile to scale so you can graft that onto your template.

Let me know if that's not okay with you guys, 9LR, and I'll recind the offer :) 

One more picture showing that "U" bracket mounted:

Finally, it's mounted!  Time to get the body work back on and the damn dam on!

WonkoTheSane (Forum Supporter)
WonkoTheSane (Forum Supporter) SuperDork
6/10/20 10:51 a.m.

I just realized I never finished updating this thread.

I spent way more time than I should have had to getting the splitter mounted up.  At this point I'm thinking I lost more time than I gained by using the PDF, or at least broke even.   Very disappointing. 

To recap, this was what I got from 9LR (with the dimensions obscured and intentionally crappy quality for this post):

The problem is that either the slot is on the wrong side, or the profile on the back is upside down.  If the slot is supposed to be on the opposite side, it should be displayed as a hidden/dashed line to indicate that, and the view should have been labelled appropriately, "Bottom View, Top View, etc."  And the back is completely wrong anyway relative to the Sturdy Boii mount holes.

When I went to mount the air dam, I noticed this:

Now, that's obvious to anyone who has used mounts like this to support an air dam, but as a complete novice, I didn't realize that the front of the Sturdy Boiis were supposed to be flush with the slot.

There wasn't enough adjustment in the slots, so I ended up re-drilling all of those holes .75" closer to the front to get the Sturdy Boiis to mount flush:

That slide the whole splitter back, of course, which meant more cutting to the backside:

So for the record, that was 2.5" of material total cut from the back end.

But it's finally on!

WonkoTheSane (Forum Supporter)
WonkoTheSane (Forum Supporter) SuperDork
6/10/20 11:03 a.m.

Now that the splitter is FINALLY in the right place, it's time to get the air dam on.  For this, I mocked it up in place to see what was required to cut. 

Here's the minimum it takes to get the bumper mounted:

After that I figured where the top of the dam will go, and marked that to line up to the middle of the bumper:

You can cut it off as far up as you want to within about 2" of the seam (the pre-drilled holes in the dam are .5" below the top).   I didn't cut any more yet, because I needed to mount my side markers (more on that later).

After that, it was a real pain to try to get it to wrap around.  It would have been a lot easier if they has wrapped it up the opposite way for shipping, as it was curling in the wrong direction.  I had to use a heat-gun a lot, and then wrangled it back to clamp it (no pictures during this bit, but you can see the clamp holding it to my bumper in this pic).

After that, pop some holes in and get your rivet game on:

For my purposes (still street-legal), I wanted to use the stock side markers, so I just marked out where they were with painters tape left-to-right, and measured how far down the center was.  Then I used a dremel with a spiral bit to cut out out the slot.

Finally, I needed to get my brake cooling kit intalled.  I went with the Singular motorsports brackets and kit from Good-Win-Racing, which came with the front grommets and hose.   I had to cut my bumper back a bit to make it easier to route hose, so I did that with a multi-tool:

Here's the finished product!


Marcus_NineLivesRacing New Reader
7/7/20 9:38 a.m.

Solid thread! I appreciate the effort you put into this. As with any multi-piece component kit for a car, it will be a tad different for each user and their own chassis.

It's also interesting what you ran across with the PDF, I have all of the prototypes in my garage and they all lined up on my NB steering rack properly. Maybe the file Johnny used for the PDF is off or maybe it got off during the conversion to DFX?

Hardware note, the m6x1.00 bolts used to mount the top of the sturdy-bois, there's already two on the frame(unless yours are gone) so we include the other two required.

QA note, which holes weren't all the way punched through? We've got another full-time guy in the shop to help Johnny, so I'm confident these things shouldn't happen anymore, but we always like to know small things to improve.

Air-dam note, yes as you found out the front of the sturdy bois sits flush with it. It was designed to be at a 4.5* angle for the air-dam, to be in compliance with NASA 5* limit.

Splitter note, have you made side-supports yet? We talked about putting some cables in with the kit, but it would have increased the cost for just the splitter by about $40 for $15 worth of parts. We opted to have users choose their own on this part. Also, 3" is the default size to comply with GLTC rules. Some gains can be had with 4" and we saw diminishing returns after 5" on CFD runs.

I'm ok with you sharing your DFX file with other PDF owners. Obviously letting them know this is still a very DiY route.

So have you gotten to the track with it yet?! At the end of the day, we love seeing people being able to go faster after getting this setup.

WonkoTheSane (Forum Supporter)
WonkoTheSane (Forum Supporter) SuperDork
7/7/20 3:38 p.m.

In reply to Marcus_NineLivesRacing :

Good timing to bump the thread, I was going to update it today with results :)

To answer the most important question first:  Yes!  I dropped almost 3 seconds off of my personal best at both Palmer Motorsports Park and Thompson Speedway in the past two weeks!  It was enough to win my class @ the SCCA Time Trials National event this past weekend :)

I'm not a terribly aggressive driver, and this kit makes me feel a lot more confident.  I'd liken it to driving your car on track right after you put in your first race seat and harness.  

I do need more springs now :)

It's also interesting what you ran across with the PDF, I have all of the prototypes in my garage and they all lined up on my NB steering rack properly. Maybe the file Johnny used for the PDF is off or maybe it got off during the conversion to DFX?

Absolutely possible.  I had to convert from PDF to DXF using Inkscape, and then after cleaning up the DXF in my CAD/CAM system, I had to scale it to the dimensions given.  I did the conversion 3 times to make sure it lined up to the best of my abilities (i.e., I didn't fat-finger something somewhere). 

I'd happily send in my DXF to compare to yours if you'd like to check?  I have to say that I was disappointed that I didn't just get a already-to-size DXF without properly labeleled views and dimensions other than those two..

Hardware note, the m6x1.00 bolts used to mount the top of the sturdy-bois, there's already two on the frame(unless yours are gone) so we include the other two required.

That makes sense.  This car was a spec miata before hand, so pretty much everything unneccessary that was legally allowed to be removed was already.

Splitter note, have you made side-supports yet?

Not yet, but I do have to snag a picture of my last mod done to the splitter.. was obviously having some deflection as the dam kept popping out and there was a bunch of gravel and rubber getting jammed in the little slot.  What I did was just put some "L" brackets behind the slot (only secured to the splitter) and a bead of RTV in front of the dam.  Seemed to work great.  I'll make side supports if I still seem to be getting separation after this, but it's hard to beat a $5 tube of RTV :)

QA note, which holes weren't all the way punched through?

I'd say about 75% of them on the brackets were not punched through. It looks like the normal smearing you'd get drilling aluminum where you pushed some material at the end instead of cutting it.  The base that mounts to the splitter was fine.

Marcus_NineLivesRacing New Reader
7/19/20 8:37 a.m.

3 second improvement, hell yeah! We're there any other changes to the car?

I too had to up my spring-rate, was slamming tire to frame in a couple of spots I didn't before aero.... including some braking zones lol.

I've also let the guys know about the holes not being punched through. 

accordionfolder SuperDork
9/17/20 10:47 a.m.

In reply to WonkoTheSane (Forum Supporter) :

Love this thread - considering the same setup for my track rat - What class did the aero slot you in for TTN??

WonkoTheSane (Forum Supporter)
WonkoTheSane (Forum Supporter) SuperDork
9/17/20 2:20 p.m.

Oh man, I never replied to Marcus! I'm sorry mate!

Thanks for pinging me on this, Accordion!  The only other changes I made were to use some things I had on the shelf for another car.. I put on the Paco Motorsports front arms and the flyin Miata rear subframe brace.

Accordion - they put me in the P4 class for TTN.  I'm not a big rule guy, and I've found that it really doesn't help me much with the SCCA, so I always just ask them where they want to put me :). I only notice very obvious infractions (2.5L engine in a < 2.0 class kinda thing), so don't take this as an endorsement that you won't get protested at Nationals! A lot of those guys are way too serious for me :)

accordionfolder SuperDork
9/17/20 2:50 p.m.

In reply to WonkoTheSane (Forum Supporter) :

According to the rules I'm slotted into T5 (I think, lol), which I'll probably be midpack between the serious folk and the beginners according to last years results (so who the heck knows?). I've just been eye'ing the aero but don't want to get EVEN MORE outclassed in my tiny 1.6 N/A car with full interior, etc...

WonkoTheSane (Forum Supporter)
WonkoTheSane (Forum Supporter) SuperDork
9/17/20 3:52 p.m.
accordionfolder said:

In reply to WonkoTheSane (Forum Supporter) :

According to the rules I'm slotted into T5 (I think, lol), which I'll probably be midpack between the serious folk and the beginners according to last years results (so who the heck knows?). I've just been eye'ing the aero but don't want to get EVEN MORE outclassed in my tiny 1.6 N/A car with full interior, etc...

Yeah, I think I was in the "Ts" last year before the aero.  I will say that with the exception of having to step up my dampers and springs some as mentioned above, there has been no drawbacks to aero.  But I don't drive the car other than to the track.. I don't think I'd want the splitter on a daily beater.

accordionfolder SuperDork
9/17/20 4:30 p.m.

In reply to WonkoTheSane (Forum Supporter) :

This little monster is just driven to the track and back, it's car #6 - it's only used on smooth roads or on the interstate to get to the track. One of my primary concerns is classing with aero - unfortunately I think it bumps me up to the class you're in to which I'm under-motored for (I'm technically under-prepared for Tuner as well, but not as massively - since a 1.8 car slots the same and get another ~4+ mph on the big straights at NCM) with a whopping 90whp (maybe??) from my box-stock 1.6. But it makes great oil pressure and teaches me to be a better driver, so the VVT engine (dyno'd at 140whp) I have will wait until I break this.

So last question, I tried emailing 9lives, but never heard back from them - does the aero work like really sticky tires? Covering bad habits? I've always heard you drive an "aero car" differently, but maybe this aero is just giving the miata a bit more poke since it's fairly tame? 

Thanks for answering all my random questions!

WonkoTheSane (Forum Supporter)
WonkoTheSane (Forum Supporter) SuperDork
9/17/20 7:07 p.m.

In reply to accordionfolder :

No problem.  They're pretty busy people but active on Facebook so I've had luck taking to them there.  Yeah, the top speed hit is pretty evident if you go to higher speed tracks, I'd imagine it's worse with ~15 less hp at the wheels or whatever. 

In my completely unprofessional opinion, aero is like the opposite way to gain time over sticky tires.  The slower you go, the less grip you have, so you have to balance between carrying speed and a varying amount of grip.

It definitely alters the line that you were taking before.  I find that I'm staying mid-tight on my entry or exit where before I had to use all the track to maintain the rpm through a turn.  Now, due to the increased amount of grip, I don't have to track out as far, for example, which shortens the distance of track I use.   That's 100% due to aero for me and the lack of HP :)

WonkoTheSane (Forum Supporter)
WonkoTheSane (Forum Supporter) SuperDork
9/17/20 7:08 p.m.

If you find yourself in new England, you're welcome to take it for a session or two.

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