Cxracer
Cxracer New Reader
4/29/20 1:50 a.m.

This is probably going to be boring for most of you who have actual fabrication skills and the guts to try something out of the ordinary.

I'll start by saying I've been a big Miata enthusiast ever since a good friend of mine and Spec Miata racer talked me into a Miata around 12 years ago. He argued that it was a better track car alternative to a 240z project car I had, since I was fairly limited on time and money. He was definitely right. I did eventually get the 240z running and then realized how much more time and money it was going to take to get it anywhere near a fun sports car vs. an ugly money pit and sold it off. Since then Miatas seem to be multiplying like rabbits and our family has owned and sold a number of them (all NAs). At the moment we've got 4 NA series Miatas and a street legal Exocet Race.

The project sort of started as a dare with a friend of mine who's team had recently blown up an engine in their 5 series E30. I told him I was signing up for the 2018 Miatas at Laguna Seca event and that he should sign up too. The only catch was that he didn't have a Miata. I told him that it wouldn't be a problem, he could use the running (ish) 91 Miata that I bought for $350 as a parts car and had been sitting behind my garage for the last 2 1/2 years and a handful of second hand CL parts that I'd been squirreling away in the garage. 

 

Cxracer
Cxracer New Reader
4/29/20 2:18 a.m.

So as usual I always forget to take pictures at the beginning of projects so this is after the point that we got the car to fire up (it actually needed a bit of starter fluid to get it to catch) and then drove in onto the driveway. From there we proceeded to take the crappy Auto Power roll bar out of it and put in an extra tall Evil Genius roll bar that I picked up cheap because it won't fit under a soft or hard top. Good thing too since my friend is just a little under 6' 4". After making some new mounting plates we got the big new bar in and the Track Rat started taking shape. Just check out those incredible 17" wheels!

Cxracer
Cxracer New Reader
4/29/20 2:27 a.m.

With the bar in place of course we needed to find some race seats. Of course it was important to stay with the theme here and find seats that were up to the caliber of of this build. Not quite a matching pair but both needed some duct tape to keep the padding in place so I'll say close enough.

Cxracer
Cxracer New Reader
4/29/20 2:36 a.m.

Not wanting to skimp on safety I put together two sets of BSE (made by Schroth) 6 point belts. You might not recognize the buckles but they are from a Humvee gunner's harness and I believe the belts are from a BSE (made by Schroth) new military surplus helicopter harness. They work great and are super easy to adjust and are very comfortable.

Cxracer
Cxracer New Reader
4/29/20 2:45 a.m.

Of course a Miata is nothing unless it can handle. Let's face it, a 225K mile 1.6l is not going to thrill you with horse power so it better go around a corner.

To that end, we pulled the old blown KYB stock replacement shocks and bolted in a set of second hand Bilsteins with Eibach springs and spring height adjusters. Considering that I picked them up for $150, I'm really impressed with them.

Cxracer
Cxracer New Reader
4/29/20 2:56 a.m.

We also through in some stopping power with an old FM big brake kit on the front with VW Corrado 11" rotors and Wilwood 4 piston calipers (way over kill). Some Hawk DTC60 pads rounded things out.

Oh, and my friend contributed a set of 15" TR rims with sticky Star Specs from his E30 car to give us something better than dry rotting tires on 17" wheels to roll around on the track with.

And then it was time to make the car go straight.

 

Cxracer
Cxracer New Reader
4/29/20 3:03 a.m.

While the car was up on the rack I got a good look at the frame rails. Not exactly what I'd call straight, what do you think?

Cxracer
Cxracer New Reader
4/29/20 3:09 a.m.

After a 1/2 quart of ATF in the oil and running it at 3500 for about 20min I got the rings un-stick in 2 of the pistons probably doubling the horse power!

Oil, transmission and diff fluids all changed, it was a regular site to see a good amount of crap on the drain plugs frown

Cxracer
Cxracer New Reader
4/29/20 3:59 p.m.

Ready to go in all of its glory!

Cxracer
Cxracer New Reader
4/29/20 4:39 p.m.

So surprisingly this beauty the held up quite well on its first track day.

Unfortunately we were up until about 1am the night before the event getting the brakes on and bled correctly. My friend decided to take a nap through one of his track sessions and handed the keys over to me to take a spin. Aside from a low brake pedal engagement due to the larger calipers up front the car did really well for 255K on the clock and I passed a number cars in the session.

My friend went from "this engine is half dead" to "I'm getting faster every lap" after I explained that you need to keep your foot down and don't shift until 7,000rpm. Being used to his E30 he was shifting around 4,500 but in a Miata you are just tickling beginning of the power band. I said just wring its neck and keep increasing how much speed you carry through the corners.

After that successful outing I offered it to a friend for his first track day and even with a Corvette in the garage he was really happy with the little Miata and had a great day. Since then he drove it in the rain at Thunderhill and again at Laguna Seca for the Miatas at Laguna Seca 2019.

A 3rd friend blew up his EcoTech swapped miata a month before the 2019 Laguna Seca event so of course I offered the car to him to share (run the car in two different groups). So all in all 3 friends shared the car over the weekend of Miatas at Laguna Seca 2019. (I drove my Exocet both days)

 

Miatas at Laguna Seca 2019 (me in the red Exocet following the Track Rat down the corkscrew)

Rainy day at Thunder Hill as the Track Rat heads over the bypass on the orginal East track

Cxracer
Cxracer New Reader
4/29/20 5:10 p.m.

Remember that long brake engagement I talked about? That started turning into a squishy brake pedal and that was diagnosed as a leaky distribution block at the rear brakes.

Trying to fix more than pressure loss I decided to MacGyver a master cylinder solution that would up the volume of fluid pushed into the bigger calipers and raise the brake pedal engagement. Another nice side effect is that it reduced the brake line pressure ratio to pedal pressure so it made the larger brakes easier to modulate.

Enter the Ford Explorer 1.05" bore diameter that fits (ish) the NA brake booster. Aside from a bunch of SAE to metric flair adaptors and an interesting adjustment to the interface rod coming out of the booster it fits and works great. The pedal engages high enough for proper heel-toe and is nice and stiff making it easy to modulate and get right up to the limit but not lock.

Cxracer
Cxracer New Reader
4/29/20 6:32 p.m.

So speaking of brakes, one of the things I've learned is that taking aggressive track pads and oversized rotors and putting them on an underpowered car driven by beginner and novice drivers means you don't generate a lot of heat. The byproduct is premature wear on your pads and rotors. 

These pads and rotors made it through 6 or so HPDE sessions (the rotors were already a little used but the pads were new) and the result was almost completely used up front pads with rotors that used to have slots being polished clean. The rear pads and rotors held up better but really only have half their life left. Luckily the Corrado 11" rotors are pretty cheap when you can find them. We decided to switch to DTC30 pads on the assumption that their lower working temperature would mean less wear.

Cxracer
Cxracer New Reader
4/29/20 6:45 p.m.

Well, I guess you can only expect your luck to hold up for so long before a 255K engine might decide to stop turning laps. Unfortunately for us it was the first session of the day where 3 of us were going to share the car. It was running great until our first driver noticed the stock temperature gauge started to spike on the way up towards the Corkscrew and by the time he pulled into the pits all of the fun had leaked out.

It was all due to that stupid rubber coolant plug Mazda decided to cap the back of the head off with instead of some sort of indestructible metal plug! The genuine Mazda rubber plug is robust but they obviously didn't plan to make a part that would last 255K and 28 years,

After pouring water into the radiator and watching steam come out between the head and the block we knew our day was over.sad

Cxracer
Cxracer New Reader
5/1/20 9:26 p.m.

So, since that sad day last November the car has been parked in front of my garage.

 In the meantime lacking the time and motivation to get the engine fixed I decided to do the next best thing and grab all of my friends who had driven the car (3) and one more friend of the Exocet persuasion, and invited them to form a team and build this little bugger into an enduro race car. I figured if I could talk 4 others to help split the costs and some of the work and help keep me motivated that this car could actually be turned in to the first w2w I've had a chance to race.

Cxracer
Cxracer New Reader
5/1/20 9:29 p.m.

First step forward 

jimlowe
jimlowe New Reader
5/2/20 2:04 p.m.

The  Cursed Water Plug strikes again!  That, and the Devil Hoses, have waylaid and sent many a Miata to a premature grave.

Looking forward to the endurance race car resurrection.

Cxracer
Cxracer New Reader
5/2/20 6:21 p.m.
jimlowe said:

The  Cursed Water Plug strikes again!  That, and the Devil Hoses, have waylaid and sent many a Miata to a premature grave.

Looking forward to the endurance race car resurrection.


You can see the damn coolant line still dripping out the back of the head as we hauled it out. 

Cxracer
Cxracer New Reader
5/2/20 6:25 p.m.



pulled the blown 1.6 engine and sold it to a guy who is going to rebuild the lower end. His car had a 1.6l with a short nose crank that someone JB welded the pulley on.

jimlowe
jimlowe New Reader
5/3/20 9:37 a.m.

That puffed up heater hose looks a decade past its prime also.  Part of the problem is that oil leaking from the CAS right above the Devil Plug pretty much eats the plug up in short order, spreads to the heater hose, and eats that too.

At least before the next motor goes in you'll have excellent access to check over and correct all of those weak links inherent to Miata engines.  To be fair, 28 years and 255k miles is pretty good service from rubber hoses and nipples, and if that CAS hadn't been leaking they'd probably last considerably longer.

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