Splitter, and Faster!

I had gone back to The Ridge and had the success I thought would be “easy” for GTA.  But, my splitter was beyond repair.  It also wasn’t nearly as effective as it used to be.  Every time a support rod failed, it was violently flapping in the 100+ mph wind.  The core had been compromised, it was too flimsy to be trusted any more. 

I know when I made this splitter, I said the next version would be a composite sheet.But after a lot more research, it sounds like alumalite isn’t that ideal to use. AJ Hartman aero has a quality youtube channel, and he explains it better than I here:

About $350 for a 10mm white sheet is the best I could find locally.   

So, off to Youtube University I went.  The streetclass winner at GTA, Jared with the Sector One s2000, had built a simple splitter with a birch plywood core, and single layer carbon exterior.  He said it wasn’t that light, but ridiculously strong. 

Let’s give it a shot.  The plywood cost about $60, and the carbon material about $220. 

I bought a very nice sheet of 3/8” birch (birch is light and strong) plywood from a local wood specialty shop.  Home Depot usually carries 1/2”, maybe 1/4”.  If you used more carbon you could get away with 1/4”.  If you use no carbon you could use the 1/2”.

Trace out your old splitter as best you can, and cut with a jigsaw.

Then I sanded the leading edge.  Ideally you want the larger radius curve to be the underside of the splitter.  In this pic the bottom of the splitter is the left side of the wood. 

I wasn’t sure if one layer of carbon sheet would leave some exposed wood to be seen beneath it, so I gave it a coat of black stain.  I chose stain so the carbon epoxy could still soak into the wood vs a paint, which would just be a layer on top that could fail. 

I don’t think I needed to do this in hindsight. 

For the carbon layup, I followed this great blog as close as I could for an S2000 build, just with a different core.  S2000 SPLITTER

Basically, put down a layer of epoxy with a squeegee, then lay the carbon cloth, then epoxy over it and finish with more squeegee work.  They used plastic sheeting as the epoxy cured to help keep the top layer nice and even, so I thought I could do the same.

The next day when I peeled the plastic… I was pretty disappointed.

That’s literally the “finished” surface.  Luckily I laid up the bottom side of the splitter first, so this was my test.  For the top, I think we’ll try a simpler method, just let the epoxy cure without a plastic sheet on it. 

To try and salvage the underside, I hit it hard with 80grit on the DA sander and when it was nice and smooth, I squeegee-ed one more coat of epoxy.  It’s not pretty, but it’s nice and smooth to promote proper airflow. 

The topside turned out pretty nice!  It has a 3D textured finish to it. 

Yes you can tell it was done in a garage by a novice… because it was done in a garage by a novice.  But hey, that’s how we learn.

If I had a large enough piece of glass, I would’ve attempted a vacuum bag layup process.  Basically you seal the entire piece in plastic and vacuum out all the air.  This provides a nice uniform finish and eliminates any air in the piece.  I plan to try some smaller pieces that way this summer. 

I gave the splitter a coat of rattle can clear to help protect it from UV damage.And moved onto building a skid protection system.

There’s a few vendors that sell splitter skid plates/pucks.  It’s inevitable the splitter will touch the ground sometimes.  If you add some skid pucks, they’ll be sacrificed before your splitter ever touches the ground.  Mostly vendors make them out of titanium.  It’s very light, and produces those awesome sparks you see when contacting the ground at speed.  See:  Every F1 car.

The titanium pucks are badass, but I’m on a budget!  So, I picked up a 1/2” thick plate of scrap steel from work.  I wanted four pucks, two in the front, and one on each end laterally.  I thought, why not use the end plate mounts?

So I made these simple skid pads, and tapered them for best airflow.  I tapped them for the bolts holding the end plates up.

I liked how those turned out.  For the front skid pucks I wanted to use the same holes as the splitter support rods.  Get two birds stoned at once.  I made these round as they only have one mount hole, and any ground contact might spin them around some, I didn’t want their aero effect to be mitigated. 

I also painted them all black, they’re bound to rust a bit but I didn’t want them to be a total eyesore. 

Moving onto mounting the splitter.  I wanted this to be stout!  I also didn’t want to have to attach it to my bumper in 15 places.  Ideally I would have 6 attachment points to make removal a 10 minute process.  I would love to have a trick system to remove the front bumper and splitter in 30 seconds to load onto the trailer… but we’re not at THAT level of racecar… yet. 

I wanted as few holes in the splitter as possible.  So I used carriage bolts on the underside to make it as smooth as possible.  These worked really well!  I also used aluminum angle to keep things light. 

The quick release style cotter pins were an experiment, which failed.  They just didn’t seem trustworthy.  I swapped to bolts through the uprights later.  You can also see the lateral support I built with some aluminum flat stock.  This bolts to the framerail of the car on the OEM radiator support. 

With the splitter test mounted, I installed the Pro Awesome splitter rods again (VERY tight this time).  Time for a stress test!

Success!  With minimal deflection too!  I’m about 160 pounds for perspective.  The new splitter is a bit porky, 28 pounds with all the mount hardware.  About 4 pounds heavier than my older one….BUT it’s probably 5 times stronger.  With added weight as low to the ground as possible, I can live with it. 

Now that I was happy with the mounting, it was time for the airdam.

I should’ve built a new airdam, but another track day was pending.  So I re-used my old one.  It’s made of some aluminum angle (with lots of cuts in it so it can be curved) and stock car plastic sheeting (cheap from Jegs).

It’s mounted with some short wood screws.  They don’t go all the way through the splitter blade, we’re trying to minimize penetrations through the underside of the splitter.  Since the core is wood the screws had plenty to bite into.

With the splitter finished, we had a track day at an old enemy of mine, Pacific Raceways.  Five years ago, this track claimed my first MR2 build.  Looking back, my tires were pretty much bald, and was still a very novice driver in the wet. 

It’s an intimidating track.  Built in 1959, it has a huge history of racing in the PNW.  Unfortunately, all the little trees in 1959 are now big.. and close to the track.  There’s only a few safe runoffs around the entire track.  I did come here last year before GTA to shake down the car, and was very happy to run a 1:34.4 lap.  But, over the last year, I feel my driving has grown leaps and bounds.  I came into the day with a goal of sub 1:31 on A052, and hopefully sub 1:30 on the Hoosier A7s.

This was a twilight track day, meaning it started in the afternoon and you got 5 sessions, but they’re also 30min each. A solid amount of track time for the price. 

The first few sessions were very busy.  I rarely got an open lap, but did manage to get my times down to the high 1:32s. 

On the 3rd session, I found a fast car to chase, a 911 GT3rs Weissach package.  One of the most beautiful cars made in the last few years, and ridiculous performance to boot.  I pointed him by to give chase and hopefully learn a few things. 

 What a fun session!  We had a hell of a time playing cat and mouse.  He obviously had me on the straights (500+ hp), but the corners I was catching him, with more brave cornering speed and better lines.  I have to give the owner credit, I’d be pretty timid driving a $250,000 super car at that pace around a track that has trees 3’ wide around every turn. 

 After the session I found the owner and introduced myself.  He couldn’t have been a nicer guy, and was asking about my line choice (especially through 3a/b, the two hairpins).  We hi-fived and I was hoping we’d get to play more out there, but he left after that session. 

In the Porsche chase laps, you see my predictive timing had a low 1:30 on that lap, maybe even a 1:29… but we hit traffic on the front straight and I ended up with a 1:31.1. 

 I could tell people were starting to leave, and we still had 2 sessions left.  So, on went the Hoosiers. 

The 4th session was a good one, but I was still catching traffic at inopportune times.  Everyone did a great job checking their mirrors, but it’s tough to set a PB when you’re on the track with guys going 10-20 second slower pace.  I came in with two 1:30.0 laps on the timer.  So close!

I had to go out for the last session, even though I was exhausted (I had worked a full day at work that morning).

 The last session had beautiful sunset light, which was BLINDING going into turn 2, coincidentally the biggest braking zone of the entire track.  That being said I took it conservatively there and still ripped off a 1:29.1!  I know a 1:27 is possible with braver driving and better conditions.  The Hoosier A7s are still a paradigm shift for me.  They can stop in 2/3 the distance the A052 require, and can brake and turn at the same time MUCH better than the A052.  With more seat time these tires can really push the chassis to the limit. 

 Overall a great day, learned the track fairly well, and really want to come back this year.  Not to mention, it’s only 45 minutes from my house (Ridge is 1hr45m).  The car performed great all day.  I heard the splitter scrape the ground a few times, and no damage, the pucks worked as intended.  The front end felt solid all day very planted and no flapping at 130+ mph. 

No Ego, All Fun!