NC Autocross and Track Build

I have been reading GRM since my youth, and finally the time has come for my own car build. Miata is always the answer, so I tried earlier in life with a NB. Turns out my weirdly long torso doesn't agree with any reasonable roll bar and seat combo, so while I did a couple autocrosses, I let the NB go quite a few years ago because I couldn't safely track it. It is still in the family, my dad drives it with a FM2R added. For reference I'm 5'10", my dad is 5" taller but is all arms and legs, so he fits well enough for street use in that car.

After some conversations with people from Flyin' Miata, Brian Goodwin, and some locals, I determined that should I ever get another Miata, it should be a NC. The weak link was still the roll bar, besides a custom solution there really wasn't anything that was going to work for me. Then a couple years later I saw a thread on the Miata forum about a new roll bar from Blackbird Fabworx. Eventually the owner of BFW got me in touch with someone within an hour drive who had one installed in his car, and I managed to go sit in it. I cleared the stick from the windshield frame to the roll bar by three fingers without helmet, and was just touching it with a helmet on. I was pretty happy, and have been plotting to get a NC ever since, that was about 2.5 years ago.  I spec'ed out how I would do a build for autocross and HPDE, and things pretty much went dormant due to life for the next couple years. 

Early this year, I updated my build chart prices and suppliers. I then started doing research on the Miata market for the next few months. Once the covid19 thing took off, I noticed that prices started falling, and figured it was time to get one. My family out-schemed me though:  a couple weeks ago, I was servicing my Subaru daily driver, when my dad pulled up into the driveway with this:

Thanks dad!

Let the repairing, maintenance, modification, and fun, commence!!

In reply to Benjamin Jolly :

The car is a 2007 Copper Red Mica Grand Touring, with the 6 spd manual. Just over 100k miles, clean and straight. Some minor cosmetic problems, and a couple issues I'll get to later, but the stuff that really counts is in great condition. 

Having done my research on these vehicles, I knew the cooling system has a very weak link: the plastic expansion tank. I think the car had been in my garage a day when I ordered that, and a few short days later it showed it at my house. I chose the one made by Moroso, sold by Good-win Racing. It was a very painless modification, and thanks to a $7 pump from the parts store down the street I spilled less than 1/2 an ounce of coolant doing the swap. 

Before:

After:

The sight glass on the side is a nice touch too. 

I'm looking forward to following along. I picked up an 06' last summer and I am doing some mods this year to hopefully perform a little better in STR class.

That new reservoir looks sharp. I cheaped out and did a replacement Mazda unit as it was 13 years old and quite yellow.

What are some of your future plans from a modification perspective?

My objective for this build is to put a car together that I can enjoy driving on the street, Colorado has a lot of good sports car roads. I also enjoy driving faster, hence the need to move to a (somewhat) controlled environment. 

I have a lot of learning to do, so I plan on starting out in some autocross and eventually heading to HPDE. My plan is to build the car to fit into the Street Touring Roadster rules, as they allow me the freedom to modify some things I want to that would kick me out of the 'street' classes. 

Safety is one of my biggest concerns. Having been a follower of motorsports my whole life, and from some work as a flagger and official around the race course, I have personally seen some pretty hairy situations. I have watched a few of my favorite drivers die on TV.  Recently, I watched my man Robert Wickens receive some life-altering injuries in his crash at Pocono. I accept that one cannot remove all risk from motorsports. That said, I have always felt safer at the track than I did driving on the public highways to reach the track. I plan on doing my part to keep things that way.

Starting with the monkey behind the wheel, I always wear long pants, long sleeves, and closed shoes when doing anything competitive or working at the track. When working, safety glasses, hearing protection, and some heavy duty leather gloves have always been part of my gear. Driving, I have always worn a full face SA rated helmet. Since it has been many years since I have driven, it was time to get a new helmet. My understanding is the SA2020 helmets won't hit till this fall, so I chose to buy a SA2015 helmet now. I found a great deal on a Impact Racing brand helmet from Summit Racing, it fits great, fit the budget, and was made by Americans in Indiana. The cool silver color is a nice change from white or black too. 

Moving to the car, the obvious problem with the Miata is roll over protection. I personally think it is a necessity, even for street use. I know you have to do something really dumb to turn one over on a public road, but I know for a fact my neck isn't strong enough to hold up a 2300# car, to say nothing of the dynamic loads in a crash that would increase that number dramatically. So while the chance of a roll over may be remote, the consequence is so severe it must be mitigated. Some argue the roll bar is a hazard in a rear-end collision, which is more likely than a roll over, and they aren't wrong. That hazard is easily mitigated with proper padding, and will be done on my car. 

As stated in the first post, I found the Blackbird Fabworx NC RZ to be the correct bar for what I'm trying to do. I have one on order, and look forward to receiving it in a month or so. Having installed a bar in my previous Miata, helped others with their installs, and some professional experience with aircraft structure work, I believe I have the skills and tools needed to do the installation myself. I plan on properly padding the part of the bar facing the seats. I am impressed with BCSI's 'dual durometer' pad setup, and will likely install that. 

Based on my seat test with the roll bar in the other guy's car, I know I need to get that seat down as low as practical. I have done a bit of research on how others have done this, and will make a post explaining my seat lowering bracket design and fabrication when I make them and install them. 

For fire safety, I believe every car, even your daily needs a properly secured fire extinguisher at a minimum. I have ordered the materials and equipment I need to securely mount a 2.5# dry chemical unit in the car, I will do a post on that when it shows up and I can put it all together. I found a really neat bracket mount from a place in the UK.

Last, first aid is important. While it is nice to have a handful of band-aids and advil for minor things, I think the Individual First Aid Kit aka 'IFAK' is a lot more important to have than a little red bag filled with off-brand medicine and band-aids. For the unintiated, an IFAK generally contains a handful of items to control life-threatening bleeding from a traumatic injury: a tourniquet, something like QuickClot, and a few other bandages. If you haven't taken a 'Stop the Bleed' class, I highly recommend you seek one out and do it, and keep some of the stuff they teach you how to use handy. Good tourniquets are very affordable now, ~ $15. If there is some interest, I can post the setup I use and carry around. 

In reply to fusion66 :

I looked at doing a Mazda tank too, but decided to solve it once and for all. I also plan on addressing other aspects of cooling pretty early on, living in Colorado everything I do falls into the 'hot and high' category (not that kind of high ), the high altitude makes cooling a challenge.  Planning on a hose upgrade, and a larger radiator soon, along with an oil cooler. 

In addition to my safety mods, I want to tackle the suspension and exhaust. I can trim many pounds and open up some horsepower with a good setup, I'm thinking a header, midpipe, and muffler. Having ridden in some stupid loud Miatas, I want to be careful not to go too loud.

Suspension wise, I've always been a fan of Flyin' Miata. Not only can I use them as an excuse for a fun trip (~4 hours drive) to pick it up, they know what a shock dyno is, and engineer the suspension as a complete balanced system. I had one of their packages on my NB and it was excellent. I think their Koni Stage 2 package will be perfect for me, maybe next year...

I feel pretty good about the brake size on the car, for what I'm doing, I think keeping them maintained with good pads will be about it, I may go to the braided hoses for better brake feel. 

fusion66, what mods are you planning?

In reply to Benjamin Jolly :

Car as purchased came with Racing Beat sway bars (front and rear) and Koni adjustable shocks plus aftermarket springs that I have not identified the manufacturer of yet. Adjustable coil-overs are on order and should arrive in two weeks but they are a bit of a dice roll as I went with Fortune Auto which has good reviews but certainly not as respected as Ohlins or some others.

Stock rims with 215-45-17 RE-71 tires will be replaced with Enkei 17x9 rims and 245-40-17 RE-71 tires soon (I have the wheels and will pull the trigger on tires before the $70 rebate expires May 4th).

Alignment is reasonably aggressive with -2.6 camber and 1/16" toe out front and -2.2 camber and 1/16" toe in rear. 

No roll bar (only the limited factory roll over protection) so no track time in 2020 which aligns to my tire purchase as I think they are a better autocross tire than track tire. 

I have a 2.5 lb fire extinguisher and quick release mount I need to fabricate a bracket for - it's on the "to do" list.

Also planning to lower the seat as my helmet touches the top when autocrossing in the rain. 

Axle back exhaust was installed when purchased and stock location K&N filter but no idea if any power gain was realized. No plan for mods this year.

In reply to fusion66 :

That sounds like a great setup. I plan on doing the roll bar and seats this year, and probably nothing else besides maintenance, as the (abbreviated) autox season is happening soon. 

Here's the bracket I ordered for my fire extinguisher, it was ~$55 shipped to me, I don't expect to see it for a while since it is coming from the UK. It looked nicer than anything I could fab in a couple days, so I ordered it. While the fire bottle in my daily is under the passenger seat, I'd rather have this one under my seat since reaching over the tunnel is a lot harder in a Miata than in my Subaru Impreza. 

The seat lowering thing is a big deal. From everything I've seen, the idea I have cooked up should get me a drop of ~2.5". I plan to work on it some this weekend, I got most of the materials and tools I need on hand to start the process. I will have to find someone to weld the gusset in my design, since I don't have a welder yet. 

Looking forward to following your build.  If I were starting from scratch, I would definitely build an NC...

We had a '13 Club for a few years that was my wife's DD, and we ran it on the track at FM Summer Camp, and a couple of local HPDEs, but with the PRHT I was never that happy with the safety factor.  The NC has a great chassis... a little suspension work, and good rubber is all it takes to get an NC going pretty quickly around a track.

In reply to Rodan :

I ran my NB around the kart track there in Grand Junction for FM Summer Camp (sadly canceled for 2020) a few times myself... 

The PRHT is an engineering wonder, but for track use it would require a user of pretty small stature to function safely, and a very cleverly designed roll bar. 

I will certainly be putting on a serious tire set once I get plugged in enough to know what is good for the NC right now. It is wearing a set of decent BF Goodrich 400 treadwear summer tires right now, they'll have to do for the autocross and autocross school coming up in a couple weeks. I'd love to hear some suggestions from some other NC operators and what is working well for them.

I have been reading a book titled "Autocross to Win" by Dennis Grant. It is certainly aimed at someone trying to compete at the highest levels, but has a lot of car engineering advice for all of us. It is actually kind of frustrating in a way, because as an engineer by trade myself, when I read what the author says, I realize he is right, and some of things he suggests you do are a bit boring and difficult. He postulates that the best first suspension modification you can possibly make is to properly model it in software, and begin making your changes and adjustments there.  I will confess the idea of spending $200-400 on some complicated software and then spending a few weekends measuring a ton of stuff and rendering it all doesn't sound quite as fun as bolting on shiny new parts. Like I said though, I realize he's right, and if I really want to do it well and know how to adjust it well, I should probably do that. 

The number one thing he teaches in that book is to test everything you can yourself. That is something I have preached forever in my other hobbies like amateur radio. You have to test stuff yourself, just because the cut sheet says the antenna does XYZ at a certain frequency does not mean it will do that for you and your environment. 

The old steering wheel in the car was pretty ragged, so I found a decent one on eBay for $50ish and have begun installing it. Some of the trim around the steering wheel switches is missing the paint. Having seen the nice black wheel trim for this car, I decided to make my own, some 1000 grit paper and several coats of black gloss Krylon later I should be able to put the new wheel back together next Monday. 

The wheel came off easily, maybe 1/2 a turn on the parts store loaner puller and it was loose.  Now I wait for paint to dry...

It looks like I will get to drive the Miata on the course soon: I have an autocross school coming up on the 16th of May and the autocross on the day after. It will be at Pikes Peak International Raceway, with Rocky Mountain Solo .  

I have a big test all day Monday, so my car prep is going to cease for a few days while I focus on that. 

My latest mod is getting rid of the funky trunk carpet, a new carpet and a new radio antenna is on the way from GoMiata. I have saved floor mats and carpet before but alas all my tricks failed on this one, not even several days in sunlight exposure at 6600 feet could cure it 

I got the steering wheel finished and installed. I don't wish to portray the "'Instagram' everything is perfect all the time and so am I" thing, I messed up a little on my repainting of the steering wheel trim. When I tried to install after a 7 day rest, it was still a little too soft to take some wax, the cloth left some marks in the paint. I probably should have shot some clear and then waited a few more days. I'll circle back and fix that booboo down the line. Still looks ok though, this is a drivers car and not a concours prospect. It is light years better than the old wheel, and for $50 and a few cents worth of paint I can't complain. 

The trunk carpet took all of 30 seconds to put in, and the radio antenna about the same. 

I did notice when I got the car that the shifting into 1st or between 1st and 2nd was rather difficult, and it was way too easy to get it into reverse. Some study on the Miata forum lead me to replace the 'cover' in the shift turret, more accurately described as "the plastic plate that makes the reverse lockout work". 

Taking apart the console was no picnic, but a busted fingernail and skinned knuckle later I had it out and got the shifter apart. The part was about $36 from my local Mazda dealer, and they had it in a couple days. The old one was shredded: basically the part of it that guides you into 1st and 2nd was worn down, and would also allow you slip into reverse without having to push the shift knob down. I cleaned out all the plastic debris, greased the shifter per the instructions in the manual, and put it back together. About an hour job including removal and reinstallation of the console.

It feels much better, we'll see for sure when I get the car back down off the stands tomorrow. One fine point; the manual says the cover bolts should go in with a range of torque around 70-80 in-lbs. I'd stay on the low side of the torque range: one of my bolts started to spin before the wrench clicked, I said a bad word and stopped before it got worse, but do be careful and set your wrench to the low end of the range. 

Tomorrow I will get the brakes and clutch flushed and bled, and some other inspection items crossed off for the weekend's activities. 

The weekend's driving was generally successful. I completed an autocross school, and my first real autocross event on Sunday.

My PAX was abysmal, 111th out 119. On the Rookie chart I finished 12th out 17. My times improved a lot, we got four runs, and I managed to drop over 8 seconds off my first run by the final run. The course was loads of fun, quite long, my times were in the low 90s. 

The mistakes I made weren't major but in a sport of fractions of a second, quite costly. First, I failed to shut down the DSC on the car, so I imagine the electronic nanny was dragging brakes on me pretty much the whole way round. Some reading on the Miata forum indicates I can probably save a couple seconds at least on a normal course, and on these long ones probably more. Several people did say to expect to spin a time or two until you get used to it being turned off.  Second mistake I'll mention was course walking. The novice walk is a good thing, but in the future I need to take my own walk first, it was impossible to learn anything because I couldn't see around everyone spread out for 'social distancing', and it was way too slow. Lesson learned, get out there and do your own walk and notes first, then consider doing it with 'everyone'.

My next takeaway is the least fun...I have decided to reclass into C Street. Looking into the future, I am insanely fortunate to be able to even be worried about things like paying for hobby car stuff in the current economic climate.  But there is no way I am going to be able to come up with the budget to be competitve in STR. I can do everything I legally can for C Street for ~$1500, STR is going to multiply that times three or four. My main goal is seat time, and to learn to be a better driver. I get that C Street is 'Spec ND' right now, but I just think it is a better place for me to play for a couple years, and the NC is an underdog in STR too. 

So more on my changing modification plans in another post...still gonna do the rollbar, but the suspension concept is changing radically.

I like your idea of playing in CS for a while first before jumping into STR. As you mentioned, the NC is an underdog in both classes, but it can still get the job done in the right hands. CS will not only be cheaper, but will have less tuning knobs to play with (distract you) while you're honing your craft of reading the course and driving.

I haven't been to an autocross yet this season, but it has to be pretty hard to be a rookie/novice this year with the social distancing practices and what not. I was a novice in 2017, and the best tips I can give are taking several of course walks, comparing notes and asking questions of the fast guys, and riding along with those fast guys, as well as having them ride along with you. The ride along part probably won't be possible for the foreseeable future, but watching videos afterwards might be a reasonable substitute if they're available.

Keep up the good work, this is supposed to be fun after all. I get wrapped up in comparing my results to others as much as anyone, but keep in mind that PAX is an imperfect tool and is really just created so autocrossers can complain about how soft DS is.

It sounds like a great learning weekend and significant improvement was made in a short amount of time. I am a big fan of walking the course enough times (4-6 typically) that I can do a full run in my head and remember every turn plus any key points that I feel are relevant to the course. 

Running C Street will be a great learning opportunity versus jumping into STR right away. In either case the car will be an underdog in the class as you mention but the skill development will not be hampered by the change of plans and may actually be a better route. 

I look forward to seeing what you do to prep for the new direction.

Following, I love ncs and this covid crap has made is super tempting.

Good financial choice staying in CS. I had a similar experience.

I bought an NB2 for autocross and track days in 2018. It was already modified enough to make it illegal for ES, yet not any more competitive (race seat, Momo wheel, etc. with a stock suspension and drive train). It also had a lightweight flywheel which I think pushed it from STR into a modified class.

It was cheaper to sell it, and pay top dollar for an NB1 sport that was already fully modified to the ES rules than to try to get it competitive.

Thanks for the ideas and supportive comments. 

Unfortunately my PAX performance roughly equaled my performance on my FE test I took a few days before the autocross event I went to. For those who don't know, the 'Fundamentals of Engineering' is a 6ish hour long test that is basically a final on everything an engineering student learns in four years. It was a very challenging test, and I didn't measure up the first time around. I'm not a super student by any measure, and looking at the stats 2 out of 3 fail their second attempt. I really don't want to make it into that statistic,  so I am going to end up sitting out the rest of the summer's events practicing for that exam, I will take it in late August. I'm not giving up on Auto-x this year, we have a decent fall and winter season around here too, so I am going to aim for that. 

On suspension, it looks like from the Miata board, the ideal setup for a NC is the yellow Koni adjustables. The remainder is a set of 'red' 58 mm bumpstops front and a set of 'white' 58 mm bumpstops rear, and a 'yellow' rear sway bar from a RX-8.  I'm going to run the remainder of what I do this year on the tires on the car, but I'm guessing a set of RT-660s or Bridgestone RE-71Rs will be in my future.  

I'd also like to do one of the single outlet Goodwin Racing exhausts, budget permitting, but obviously the suspension is the biggest deal.

Last, the right rear wheel bearing is failing. I can hear it when I drive with the top up .  So I'm going to do those too while I refresh the suspension.  

Looks my plan to try C Street is pretty much shot. 

The lovely coolant tank is not legal for Street class, and I have no desire to replace it with a "new" plastic time bomb that has been on a shelf for at least 5 years now. I even went to the trouble of asking the Solo Board whether it was ok based on the wording of the catch tank rule, and the answer in this month's Fastrack was nooo. Would someone protest it? It seems unlikely at my level, but having been an occasional official for another sanctioning body I'm going to practice what I preach, and that is following the rules for your class.

Comparing times locally of NCs in C Street and STR, they are very close, just a tenth or two less for the STR prepared NCs compared to CS. The new plan is to stay in STR, and maybe I can put that header and exhaust in before the end of the year (after which aftermarket cats will be banned in my state ). My design is probably going to be a hybrid approach: Suspension will be the C Street suspension and I'm going to stick with stock wheels for a while. Hopefully the header/exhaust, a ECU tune, and a couple other things will give me a power bump to get me in the ballpark. 

Car is high up on stands in the garage now with the interior mostly removed for the installation of the roll bar and the suspension and wheel bearing work.

My amazing Blackbird Fabworx bar arrived a few weeks ago, and should get its first test fit this evening. I had hoped to be able to share this part of the project with y'all photographically, however the bar's maker has requested that I not do that, for reasons of protecting his intellectual property. I'll get some nice pictures once it is installed and the 'special' part is safely under the interior. I can assure anyone who wants a roll bar for a NC that retains the soft top, you will not be disappointed with this one. Having looked at the main competitor's bar installed in a car, this one is much stronger and safer: no petty bars, bolt in braces, or holes in the trunk needed. It is safely braced, and while I'm only an electrical engineer, I believe it is sufficiently braced to the rear to not fold into the passenger compartment. The finish is very good, mine is a silver powder coat. They also packed it extremely well, I think it took me close to two hours to get it unwrapped without damage. 

I had wondered about the legality of the overflow tank, ever since I saw that an aluminum radiator wasn't class legal.  Still, smart idea to look at what the classes are actually running in your area.

Good luck the next time around on your FE test. Having taken State and National board exams, I can relate.

In reply to Floating Doc (Forum Supporter) :

Thanks for the encouragement, I need it.

The radiator is another reason to stay in STR. In my question for the board I did take the "it prevents coolant leaks which take forever to clean off the racing surface" angle, but they didn't care. I understand wanting to keep the "Pandora's box" of modifications under control in Street, so that's why Street Touring and Street Prepared exist too.

I'm in the Front Range area of Colorado, so 'hot and high' describes the environment I operate the car in. In order to track the car, and have more margin for over mountain travel while pulling a tire trailer, I intend to upgrade the radiator and install an oil cooler.

an aftermarket coolant expansion tank is an idiotic reason to be bumped up a class, as is an aftermarket aluminum radiator (though I understand there may be weight implications for either).  It sounds like you're just getting started.  I would stay mostly CS legal and keep doing what you're doing.  Let someone be an shiny happy person and protest you if they want.  

In reply to Ben Jolly :

I've had a couple of rollbars from Moti for NAs. He makes good rollbars for sure. Good luck with the install.

Rollbar is going ok, having a good time getting the six 1" holes drilled for the spacers that are part of the installation. My 1" hole saw didn't work too great, so I switched to a unibit. That worked great up to 3/4" and now all hell has broken loose. I suspect some metallurgical phenomenon is going on, perhaps the metal got hardened by the heat? I used plenty of primo cutting fluid, not sure what has happened. I have resorted to using my 'hand mill' aka a Dremel tool as the instructions suggest, it is slow going but getting done.

My 100k mile 13 year old NC is from TN, and so while not to be compared to the horrors of north eastern automobiles it is a lot more corrosion than a southwestern guy like me is used to. The driver's seat belt had to get tossed, the attach point was badly rusted, and when I removed the retractor it was heavily corroded. I thought there was just a bunch of sand in the bottom of the plastic 'bucket' it sits inside of. It turns out the 'sand' was in fact all the aluminum oxide from the retractor assembly corroding. 

The misadventure continues with the rear end of the car. I have read a lot about why Mazda did the NC suspension the way they did it, but geez the NA/NB were a hell of a lot easier to deal with.  The manual and internet forums are loaded with mishaps regarding the ABS sensors, so the first thing I did was remove them from the spindle and secure them out of harms way. 

The axle nuts came off ok, 32 mm socket and big cheater. However the axles are stuck in the hubs quite nicely, hammering did nothing. The Mazda manual suggests using a 'copper hammer', which unless it is like 5 or 8 kg is probably going to do nothing, which is exactly what my collection of BFHs did.  Having permanently screwed up an axle before from excess hammering, I have decided to take another approach. Someone suggested I stand the hub-knuckle-driveshaft assembly up in a vise and PB Blaster the splines for a few days. After that I should try a puller and impact wrench, so I'll see how that goes. 

The excess sticktion is not limited to the hubs however. The driveshafts will not come out the diff, usually in Subarus and the NB I had a gentle pop with a prybar is all it took. I thought I had the passenger side free (it is the one standing in the vise now), but when I pulled on it, it separated at the inboard joint. Some research lead me to a tool specifically designed to get axles loose called an 'Axle Popper', it worked ok in a couple short YouTube videos so I have one coming from Amazon for a little over $30. I also ordered another axle from Redline Auto Parts for around $90. Some of the more adventurous on this board would rebuild the broken axle, but I have never had one turn out well so the salvage part is the best alternative for me.

The budget for this thing is going out of control, even before the axle and seat belt. I have another $200 or so I need to spend on tools I don't have and can't borrow/rent. I still have another $200 in parts I need to get to fix the electronics in the driver's door. When I looked at the total a couple nights ago it was a lot more than I thought it was up to. I think the exhaust is now off the table for a year or so, along with the radiator. If I get this thing off the stands and rolling with just the roll bar, shocks, that RX-8 bar, and new bushings all around I'll be doing all right.

I was able to get the axle I broke out of the hub. A 3 hour soak of the hub splines in a vertical orientation with PB Blaster, and about ten whacks with a little 16 oz hammer was all it took. When my 'axle popper' gets here Thursday, I'll have a stab at getting the other axle out of the diff and start it soaking too. At least something worked right today.