1994 Mazda MX-5 Miata: What's It Like to Live With?
Read the latest updates in our long-term road test of the 1994 Mazda MX-5 Miata as our editors live with this car for a year.
What do you want to know about?
- Introduction
- No Brakes. No Suspension. But Good Oil Pressure.
- Beater? That's Our Project Miata.
- A Good Starting Point
- Some Video Inspiration
- Underway
- Touching My Feminine Side
- Baseline Dyno Test
- Baseline Track Test
- Makes My Day
- Hand Wash
- Under The Knife
- Our Favorite Caption
- You Write the Caption
- A Tight Squeeze
- Suspension Ruminations
- Overhauled Suspension
- Ice Cold
- Seat Pickle And Suspension Impressions
- More Grip Than A GT-R
- The Ritual
- Sweet 16
- Preventative Maintenance
- DIY Floppy Mirror Fix
- Blast From the Past
- 6UL Wheeling
- A Weekend In the Sun
- Timeless Detail
- Refused
- T35 Torx, Round Two
- Suspension Walkaround
- Forced To Take a Breath
- Vital Fluid
- Certainly No Lack of Character
- Bringing Balance To The Force
- Small But Still Useful Trunk
- Super Mad Crazy Grip
- Small and Boxed In
- Holey Soft Top, Batman!
- Not a Lockbox
- Chassis Ruminations
- World's Tallest Pop-Up Lights
- Crapwagon
- Erratic Fan
- First Impressions of Our Well-Worn Friend
- Old Car, Old Key
- Table Scraps
- Back in the Saddle
- New Lid Changes Its Character a Little
- Coupe > Roadster
- More Room Inside Than You Might Think
- Wheels and Tires Make the Car
- Dealing With the Hard Top
- Rear Window
- It Was a Dark and Stormy Night
- Drinking Problem
- The Bonehead Rule
- Thermostat Walkaround
- In Good Company
- So, This Happened.
Introduction
You might think that a discussion regarding which car Edmunds.com should take on as our next project car would be filled with hours of heated point-counterpoint arguments, passionate pontifications and lots of beer.
Instead, it went something like this:
"We should do a Miata project."
"Yeah, you're right."
When the Mazda MX-5 Miata debuted in 1990, there was a waiting list to get one and people would stop on the street and stare at them. There was nothing like the Lotus Elan-inspired roadster on the road at the time. The Miata proved to be a simple, affordable sports car with a small, robust engine, terrific double-wishbone suspension and correct-wheel drive. Mazda sold 50 trillion of the things.
Today, a first-gen Miata is just another P.O.S. for sale on Craigslist. Yet time has only magnified the car's fundamental strengths, which creates something of a perfect storm for an enthusiast seeking to create his own personal interpretation of fun.
What We Bought
A couple months of searching and a few near-misses turned up a white 1994 Mazda MX-5 Miata optioned with the C-package, which includes a limited-slip differential, cruise control, air-conditioning, power mirrors and windows, power steering and a rather gauche interior with tan leather upholstery. When new, its DOHC 1.8-liter inline-4 engine generated 128 horsepower and 110 pound-feet torque, which seemed plenty since the durable little motor was saddled with just 2,300 pounds.
Though this Miata had been touted by its owner as an accident-free example, it had evidence of numerous minor shunts, plus countless scratches and dings and a generous serving of apathy. It reeked inside. Fortunately there was no evidence of any kind of major wreck, despite 174,000 miles on the clock. It was also completely stock.
If there's a downside to the Miata's inherent toughness, it's that the car can limp along for years with little if any maintenance, and this can breed neglect. This particular car had an engine with a rough idle and which pinged and occasionally misfired at part throttle, while the convertible top was literally in shreds, the ribbons of which were pinned to a beach towel in a hundred places and the whole mess duct-taped to the windshield header. A tacky film of tarlike grime covered the entire cabin. You could watch the pavement whiz by through the giant hole in the shifter boot of its five-speed manual transmission. Did we already mention that it stunk like a gorgonzola-stuffed gym sock?
It was perfect. After a short drive, we bought it on the spot for $1,750.
A basic DIY tune-up — new spark plug wires, adjusting the idle bypass and setting the ignition timing — cured the drivability issues. The shifter boots were replaced and the stench was largely chased out by a comprehensive de-filthing of the cabin with a bristle brush and a half-dozen potent household cleaners (we wore rubber gloves, although a Hazmat suit might have been in order).
We also threw on a later-model soft top that had been left lying in a friend's driveway after he replaced it with a hardtop. It's got a couple of small tears, but it'll do for now while we locate a hardtop of our own.
Shopping Tips
When it comes to Miata shopping, it helps to understand the changes that Mazda made to the first-generation car, which was in production from 1990-'97. The first cars had a 1.6-liter engine and a differential with a 6-inch ring gear.
In 1994 the Miata sprouted a new 1.8-liter engine, more chassis bracing, a stronger differential with a 7-inch ring gear, increased fuel tank capacity, bigger brakes and a somewhat revised interior with an added airbag on the passenger side.
The larger engine and optional Torsen limited-slip differential of these 1.8-liter cars makes them particularly attractive for guys who want to get all nutty with modifications. Guys like us.
Though the later parts can be retrofitted to an early car, your knuckles will thank you if they're already installed, which is why we limited our search to a 1994-'97 Miata. We figured a slightly ratty car would command less money than a nice one, but more important, its imperfections would make us less leery about molesting it.
It turns out that we're not the only ones who have stumbled upon this combination as the ideal Miata project car. Any rough Miata with a Torsen diff is snapped up literally within hours of being posted to the classifieds. You've got to be on your game to land the right car.
Why We Bought It
We're not going to do a year-long test of a tired 16-year-old stock 1994 Mazda Miata, that's for sure. This ratty roadster's getting a new lease on life, and its pale shade of white paint is a convenient metaphor for the blank canvas for innovation that this car represents.
Extensive modifications will be fully embraced. Faster and cooler, it will be built with an eye toward track durability while remaining a street car at heart. If it can cut a respectable lap in our local Miata time-trial series, then that's fine, too. But it's got to be cool. Think mini-Cobra, not poodle chariot. Function takes precedence over polish. You won't see Project Miata getting a custom pinstripe job or teeth in its grille opening.
With some help from the aftermarket and motorsports worlds, Project Miata will serve as a platform for sharing with you a lot of very cool hardware and tech along the way. At this point, everything is on the table — forced induction, an engine swap, a built motor. Heck, maybe all the above.
A Year of Fun
A cheap sports car has psychological implications. If you keep reminding yourself of the hobo-cup value of a used 1994 Mazda MX-5 Miata, each nickel spent making it faster will make you wince.
You've got to flip that mindset. Lubricate the brain-wallet interface by envisioning a used Miata as something more like a Porsche Boxster Spyder with $59,000 on the hood.
It's got to grow into those shoes, though, and that's part of the fun.
Current Odometer: 174,145
Maintenance Costs: $112.67
Problems: 2nd-gear synchro grinds; broken outside rearview mirror; brake pads feel like plywood; dampers are a bit tired. But, hey, it's a project car.
Edmunds purchased this odorous vehicle for the purposes of evaluation and to make it cooler and really, really fast.
Last night I drove our new project car for the first time. How was it? Well, let me just say we have a lot of work to do, starting with the stench that still permeates the interior.
Incredibly, however, even with no working suspension parts, or actual braking ability, our 1994 Mazda Miata is fun to bang around town in. The engine pulls to its redline without any funny noises, the transmission shifts well if you take your time and the steering wheel changes the car's direction even if it is in my crotch (I never did fit well in first gen Miatas. The driver's seat is just too high and the steering wheel too low.)
Other goodness is the air conditioning, which froze me out, the clutch, which seems fresh, and the oil pressure, which is as it should be.
Should be a fun year with this thing. In the meantime, I hear our Corvette Z06 is fixed. Full update on that tomorrow. Cross your fingers.
My neighbor Dave walked across the street the other day, pointed to our slightly used Miata, which was sitting in my driveway at the time, and said, "Scott, what's with the beater?"
"Beater?" I said with manufacturered shock. "That's our new Miata project car. We just bought it for the website."
"Why?"
"What do you mean?" I snapped back.
"Don't you guys at Edmunds.com have a bunch of new cars you can drive?"
"Yes," I said. "Dozens of them."
"Than why bother with this thing? First of all, it's a girl's car. Second of all, look at it, it's all worn out." Then he opened the door. "And it smells inside."
"We thought it would be fun," I countered. "It was dirt cheap, and these first gen Miatas can be cool if you fix them up. Manly too. Do it right and this thing is like a little Shelby Cobra. 289 of course. You'll see when we're done with it."
"Well, I don't get it," he says walking away. "Let me know when you get one of those Aston Martins, you know like James Bond. I always liked those."
By the way Dave drives a beige Toyota Avalon. And no, he doesn't get it.
You know those images you saw of Project Miata in its intro article? Well, that photo shoot was literally the first time any of us had driven our new old 1994 Mazda Miata with any kind of spirit.
And in those few hours we learned a lot about what's good about it and what needs work.
Hit the jump for those early impressions and the reason for the above image.
The Good:
First, the car has an immersive quality. Even this many years on, the first-gen Miata's inherent appeal shines through. And despite this particular car's neglected state, it's just plain fun to drive.
Its quick and linear steering responds to your inputs faithfully and without delay.
The spryness that results from its low curb weight cannot be synthesized any other way. It simply exudes fun.
It's quite easy to work on, too.
What Needs Attention:
It lacks suspension travel. Especially the rear suspension. Any kind of bump has the suspension working against the bump stops. Boing, boing. Not good for grip or ride comfort.
The lack of chassis stiffness is really noticeable too. The thing shudders over bumps as if its structure was made largely of crepe paper.
Wide open throttle throttle results in hilariously gradual progress. All noise and very little actual movement. The canyon road we were on creeps uphill ever so gently, and this was enough to keep the car's ass end chained to the pavement. It was impossible to induce any detectable oversteer at corner exits, even when getting all rowdy with it. A sports car that cannot powerslide is no bueno in my book. We'll definitely have to address that too.
What's Leaking:
Oh, and during said photo shoot, the shift action got stickier and stickier. As the lead photo suggests, afterwards we swapped in some fresh synthetic trans (and diff) juice. Yes, its underside is a murky mess.
The gearchanges still get a bit stiff with heat (esp 2nd gear), though, so chances are good that the clutch hydraulics are tired.
So, with that out of the way, what do you want to see from Project Miata?
You might be wondering the status of Project Miata. After all, it's been weeks since we introduced it.
The good news is we've got several areas brewing. The bad news is they'll take some time to come to fruition. And like any project, I expect some surprises along the way, so I'm reluctant to "tease." Suffice it to say that things are happening.
In the meantime we've simply been doing minor maintenance stuff. Yesterday I replaced the wipers (perfect timing, too, as some weird wet stuff fell from the sky right afterwards. Scary!), fixed the windshield squirter and tried replacing the broken side mirror glass only to find out that the replacement piece I bought doesn't fit. Apparently power mirror glass is shaped differently than manual mirror glass, and you can only buy replacement glass for manual mirror'd Miatas. Would have been nice to know that when I bought the glass...
Exciting, yeah? No, the opposite of that. But it will be soon.
Oh, and I'm thinking it'd be instructive / hilarious to do baseline performance testing of the car as-is. Sort of a "before" to compare to the changes we make along the way. What do you think?
Since "Build a Cool Miata Fever" infected the Edmunds.com offices last summer I've been saying we better get a hardtop. Can't do the car without a hardtop. First things first, lets get a hardtop.
Now I'm not so sure.
I just spent two top-down days in our project 1994 Mazda Miata and I loved it. Sure it was girly. Top down in our little white Miata is the automotive equivalent of a French mani-pedi with a yoga chaser. But I loved it anyway. And Jay Kav says my sudden urge to take a Pilates class will dissipate over the next week or two.
What do you think? Hardtop or no hardtop?
As I was wrapping up Project Miata's baseline dyno test session, the dyno owner — Mark DiBella — hollered from across the shop.
Mark: "Hey, so how'd it go? Let me guess. 98 horsepower, right?
Dang, he's good. Hit the jump for the dyno chart.
It seems stock 1st-gen Miatas are predictable things, and this car's results — 96 lb-ft of torque at 4,900 rpm and 97 horsepower at 5,700 rpm (1% weather correction; Dynojet 248 chassis dyno) — are right in the realm of normalcy. When new, its 1.8-liter engine was rated at 128 hp and 110 lb-ft at the crank.
This is not an engine that begs to be wrung out to the rev-limiter, both subjectively and in terms of actual power production. While Honda engines of this car's day are comparatively smooth and free to rev, Mazda's BP is a thrashy, trucky thing. It sounds strained under load and feels like it has a lot of rotational inertia.
You'd think this was a pushrod engine with the way torque rolls off after the peak. Mazda clearly biased the powerband to lower revs, as the torque curve is quite flat up to 5000 rpm. This suggests that they were more interested in tractability and providing the impression of snappiness, which would also explain the super-short gearing.
Still, considering it has 174,500 miles on the odo and numerous signs of utter neglect, it's to the engine designers' credit that this car still manages to make normal numbers. Inherent robustness has its advantages.
This one's for you, td53. We put Project Miata — in stock, pre-molested state — through its paces at the test track to establish its baseline performance. You've seen its baseline dyno performance already, I trust.
Hit the jump for its test track numbers. It turns out 1994 was a long time ago.
Upon purchase, this car was rolling on bald off-brand Chinese tires, so we threw on a set of summer tires and gave it a decent alignment (F: -1.3-deg camber, 0.10" toe out, 4-deg caster; R: -1.6-deg camber, 0.12" toe in). Also, its pads were worn nearly down to the backing plates so we swapped them out for Stoptech 309 street pads.
Other than those changes, it's stock. We brimmed the tank as per our usual protocol, and let 'er rip. Okay, rip isn't the right word. We let 'er meander in a deliberate fashion.
Vehicle: 1994 Mazda MX-5 Miata
Odometer: 174,866
Date: 20Apr10
Driver: Josh Jacquot
Price: $1,750
Specifications:
Drive Type: Rear-wheel drive
Transmission Type: 5-speed manual
Engine Type: DOHC inline-4
Displacement (cc/cu-in): 1839/112
Redline (rpm): 7,000
Horsepower (hp @ rpm): 128 @ 6,500 (when new)
Torque (lb-ft @ rpm): 110 @ 5,500 (ditto)
Brake Type (front): Ventilated disc, single-piston sliding caliper
Brake Type (rear): Solid disc, single-piston sliding caliper
Steering System: Rack-and-pinion
Suspension Type (front): Double wishbone; stabilizer bar; coil springs; adjustable camber, caster and toe
Suspension Type (rear): Double wishbone; stabilizer bar; coil springs; adjustable camber and toe
Tire Size (front/rear): 185/60R14 82H
Tire Brand: Dunlop
Tire Model: Direzza Sport Z1
Tire Type: Summer Performance
Wheel Size: 14x6 inches (front and rear)
Wheel Material (front/rear): aluminum alloy
As Tested Curb Weight (lb): 2,327 pounds (53.1 / 46.9 % F/R)
Test Results:
0 - 30 (sec): 3.4
0 - 45 (sec): 6.5
0 - 60 (sec): 10.9
0 - 75 (sec): 16.6
1/4 Mile (sec @ mph): 17.6 @ 77.2
0 - 60 with 1-ft Rollout (sec): 10.6
30 - 0 (ft): 31
60 - 0 (ft): 129
Braking Rating: Could be better
Slalom (mph): 64.3
Skid Pad Lateral Acceleration (g): 0.89
Handling Rating: Needs work
Db @ Idle: 51.7
Db @ Full Throttle: 83.8
Db @ 70 mph Cruise: 76.0
Accleration Notes:
Clutch doesn't want to be slipped, and second gear refuses to be rushed. Doing so results in a nasty grind. Feels tired. Smells bad, too.
Braking Notes:
Difficult to judge perfect amount of pedal pressure on initial application. Lock them up once and recovery will cost you 10 feet in stopping distance.
Handling Notes:
Skidpad - Slow reacting thanks to everything but its tires being worn out, but still respectably well balanced. Fun, even.
Slalom - Goodness! Plenty of "windup" in the Miata's body during rapid transitions make it somewhat difficult to control. Doesn't like any unevenness in mid-corner. Still, there's some fundamental goodness here - even in a worn-out Miata.
You've seen the dyno and track numbers for our 1994 Mazda MX-5 Miata, so you know it's slow and, um, slow. But even in its current tired, wornout state, this car makes me happy whenever I drive it. (And basically, I've been driving the car whenever JayKav isn't busy with it.)
This is the first time I've driven a first-generation MX-5. And though I'd hoped that first drive would come in a newer car, the fundamental goodness of the original Miata is evident in our project car. The engine doesn't do much in the acceleration department, but it sounds good, grunting obediently as you full-throttle it down the road.
Changing gears takes a deliberate, unhurried hand and smooth footwork (yes, especially going into 2nd), just as it did in our Ferrari 308 GTSi, but done right, it's still very satisfying. Even heel-and-toe downshifts are fun, though with the unadjustable steering wheel restricting movement of my leg, I really do have to get the throttle with my heel (rather than a lazy blip with the side of my foot). I guess I'd like it if I could tilt the steering wheel up a bit, but aside from that, at 5-foot-10, I fit perfectly in the car.
Steering response isn't exactly crisp, but there's a directness here that our 2006 MX-5 never had. Worn suspension bits keep the car from changing directions with much immediacy, but there's still a trustworthiness to the way the car behaves. Right now, a lot of it has to do with the nice new Dunlop Direzza Sport Z1 tires, I'm sure. But every time I drive this car, I get the feeling that with some new stuff to hold it up, it would really be great. And I'm now giving serious thought to buying my own Miata project car.
Here's a little slice of our 1994 Mazda MX-5 project car's life. There are a couple tears in its vinyl soft top that keep it from being perfectly watertight, so it can't go on the tracks at our normal car wash. But a $50 detail isn't really my speed when I'm driving this car. So instead it's $2.50 in quarters at the self-serve wash. Actually, it was $5 this time, because I got timed out when I paused from scrubbing to take a photo.
The tears in the top really aren't as big a deal as you might think. With the top up, the noise level is still bearable on the freeway — even with the wind leaks. I guess it's because there's not a huge amount of motor making a racket, nor do you have gargantuan tires pounding against the pavement.
More importantly, on this occasion, I successfully washed the car without water leaking into the cockpit. It did get a bit musty smelling, but I think that was from my wet shoes on the old carpet. And within a couple hours, the cockpit reverted to its usual old library stacks odor.
What's that? Shut the heck up and start spinning some wrenches on Project Miata? Right, then.
Here, our longterm Miata is under the knife at MD Automotive in Westminster, CA, where the owner was kind enough to let us use his lift, tools and sage advice. Lots to talk about in the coming days. In the meantime, you should be able to spot what we're up to here.
Thanks to ergsum for this week's favorite caption.
Here are the others that put us in a lather:
Another Edmunds.com soap opera... (technetium99)
Preparing for the soap box derby. (technetium99)
Soapy and the Bandit (ergsum)
The Fast and the Filthiest (ergsum)
Almost daylight. Gotta get rid of the evidence! (zoomzoomn)
Dirt track? What dirt track!?! (zoomzoomn)
Help me, Soapy Wan Kenobi! You're my only hope! (technetium99)
Zoom, Zoom . . . now with scrubbing bubbles! (wshuff)
An afternoon with The Mechanic just cannot be washed of. (snipenet)
The Miata has always been such a bubbly little car! (powell_jr)
I thought you guys said you were going to "soup up" the Miata, not 'soap up!?!" (technetium99)
Out, damn'd spot! out, I say! (johnmarco)
Lifestyles of the Riches and famous (stpawyfrmdonut)
Hey! Who's scruffy looking?! (sherief)
99 44/100% pure fun. (greenpiece)
What was your favorite?
Senior Editor Erin Riches shot this photo when she hand-washed our 1994 Mazda Miata.
We suggest: Mr. Bubble leaves no bathtub ring.
What is your caption?
We'll post our favorite this afternoon.
Here's 6-foot 2-inch-tall me behind the wheel of our 1994 Mazda Miata long-termer. Yes, the seat is all the way back. My right foot is on the gas pedal and my left foot is on the dead pedal, just as it would be after releasing the clutch.
With my feet so placed, my right knee makes friends with the parking brake handle while my left knee sits wedged between the door pull and the steering wheel. At least my knee makes a convenient place to rest my hand while cruising. But during spirited driving I'm forced to shuffle-steer the damn thing.
You would think I would hate this car, but in fact I own two of them. One is a bone-stock 1990 I used to race between 1991 and 1994 with stock seats (mandated by the rules), an identical stock steering wheel (ditto), an added roll cage and, of course, a crash helmet.
How did I ever fit well enough to race one of these?
I was able to manage it by removing the seat fabric, cutting about half the seat cushion and seat back foam away, then reinstalling the seat cover. This minor transgression of the SCCA Showroom Stock rules allowed me to fit because I was able to sit an inch further back and almost two inches lower down. As an extra added bonus, the unmodified seat side bolsters ended up taller by a like amount and I had better thigh support.
Even with this mod, space was tight. The roll cage had side impact bars that didn't (couldn't, per the rules) penetrate into the doors and the factory hard top had to be bolted in place. I had to practically fold myself in half to get behind the wheel. At first I got laughed-at by my track buddies, but I didn't care because the Miata was the car to have back then if you wanted to win.
But the comical picture of a small car and a tall Dan nevertheless led to my race team's name, Actual Size Sports, which later got shortened to be my customary internet handle, actualsize. Mini didn't make it up, and it's not meant as a double entendre.
As for the seat trick, Jay's got something else in mind for the long-term car.
One difficulty with modifying suspensions is that, on the surface of things, doing it right looks deceptively similar to the way an ape would approach it. There's some amount of additional spring rate and maybe some thicker stabilizer bars, and some stiff dampers for good measure. Ook ook.
However, things become much clearer when you go back to the basics. Those basics aren't spring rates or the diameter of the bars, either — those things are actually the outputs of the suspension modification process, not the inputs. What we're actually interested in when we talk about the fundamentals of revamping suspensions is ride frequency and roll couple.
Come join me on the other side of the jump where we'll skim the surface of this suspension nerdery a bit and apply it to Project Miata.
In a way, the stiffness of your car's coil springs are only as high as the suspension geometry allows them to be. You'll notice that Dan Edmunds points out the suspension's motion ratio in his suspension walkarounds. It's important, and here's why.
A strut-type suspension has a high motion ratio since it locates the spring very close to the wheel, so the coil spring "acts" stiffer. The double-wishbone setup locates the spring further inboard, giving it relatively low motion ratio because the wheel acts like a longer prybar, effectively making the spring softer. More mechanical advantage, in other words.
Take two cars that are identical except that one has a double wishbone suspension and the other has a strut-type setup. Same weight, spring rates, everything. If you were to drive each car over a speedbump, the strut car would ride much more firmly than the other (forget about dampers for a moment). This is because of the suspensions' differing motion ratios and the resulting effect on ride frequency.
Ride Frequency
Back to our bouncing cars — the frequency at which each car bounces is its ride (or bounce) frequency, and it's one of the first things you should decide when modifying your suspension.
The higher the ride frequency, the firmer the ride. Plain-jane modern street cars will be in the 1.0-1.5 Hz range for comfort. Modern stock high performance cars generally hover closer to the 2.0 Hz range. The rear ride frequency is typically about 15-20% higher than the front to keep the rear end's activity in sync with the front — after all, the rear encounters each bump after the front does.
Because Project Miata is to be a dual-purpose street/track car, a ride frequency roughly in the 2.0 Hz ballpark is what we're after, up from about 1.15-1.20 Hz stock. We want quicker responses and more capability, but not a punishing ride.
That's great and all, but the spring rates that provide the desired ride frequency don't necessarily provide the right amount of roll stiffness.
Roll Couple
Enter the stabilizer bar. The effectiveness of a stabilizer bar depends on its diameter, the length of its arms that twist the bar and the location of the endlink that pushes on the arm. If you also know the stiffness of the bar's steel, you can calculate the bar's stiffness, and from there you can dial in the right amount of roll stiffness.
The "right amount" is up to you. For us, well, we like the stock Miata's neutral handling balance, so we'll stick with a setup that emulates the stock front/rear roll stiffness relationship, aka roll couple distribution.
At this point, you can try to figure it all out yourself, measuring the suspension geometry and selecting springs based on your desired ride frequency and bars to provide the desired roll couple. Be advised, there are a lot of assumptions in there and you will be turning a lot of wrenches to get it right. And we haven't even started to talk about suspension tuning considerations like shocks or suspension travel.
Fat Cat Motorsports
Through the magic of the internet, Shaikh from Fat Cat Motorsports found our Project Miata and offered to help. He's done all the math, trial & error and tuning tweaks — in the process creating a detailed Miata suspension calculator — and has come up with a bolt-on set of coilovers for us based on the principles outlined above, and more. As you can see here, they're now on the car.
More details in a followup post.
Ditching Project Miata's stock suspension wasn't a tough decision. The tepid roll stiffness and tired dampers meant that when driven over bumps of any significance, the car was constantly bouncing off the bump stops. And although you could sense the underlying Miata goodess, it was covered in a thick layer of suck.
The colorful bits you see above — Fat Cat Motorsports coilovers, a Racing Beat tubular stabilizer bar and 949 Racing endlinks — represent a first step in eradicating the suck.
Hit the jump to see what they're all about.
Now, it isn't unusual for stock cars to employ the bump stops as supplement spring rate to the coil springs, but we're talking 1994. Bump stop technology had some way to go. An NA Miata's bump stops were made of hard rubber. Not quite hockey puck material, but getting there.
Together with the scarce bump travel of a stock Miata's suspension, the effective spring rate goes from very soft to holy crap in a hurry. This nonlinearity in spring rate makes for a car that is bump-sensitive, a situation that has obvious ride and handling implications particularly when the dampers are worn.
Fat Cat Motorsports Coilovers
Fat Cat Motorsports (FCM) coilovers address the Miata's inherent issue of limited travel from a number of angles.
First, the upper shock mounts use a later Miata (NB) configuration, which locates the bump stop higher, allowing for more bump travel.
These bump stops are also shorter than stock and made of a material that provides a more progressive increase in spring rate than the hard stock units.
And of course, the higher coil spring rates do a better job of preventing the suspension from bottoming in the first place. Our FCM coilovers have 425 lb/in front and 300 lb/in rear spring rates, which get us in our 2.0 Hz ride frequency ballpark.
With the increase in bump travel allowed by the FCM coilovers, we've lowered the car by about an inch to bring the center of gravity down a bit. Lowering is a tricky subject — lower a Miata that still has the stock upper shock mounts & bump stops and you'll pound your kidneys out. Plus, go too low and bump steer can become an issue, never mind scraping everywhere.
With these coilovers, an inch is groovy. I can deal with that. It'll look better too, so Oldham will be happy.
Stock dampers are a twin-tube design, while the FCM shocks are custom-valved Bilstein monotubes. Monotubes have a larger piston area, which allows them to generate meaningful damping force at very small shock movements. In other words, the shocks can actually damp those movements, improving control.
Monotubes also dissipate heat better, which reduces damper fade that can occur when driving over rough surfaces. Probably not an issue on a smooth track, but nice to have on, say, the road to Mount Gleason, a rough, unmaintained stretch of tarmac that's one of our faves.
Unsatisfied with the valving on the stock Bilsteins that came on certain NA Miatas, revalving has allowed FCM to tailor the damper force as they see fit. These coilovers are FCM's entry-level offering and so the dampers have fixed valving, i.e. compression and rebound are not adjustable.
In case you're wondering what the heck this little dongas on the shock body is all about, it's a shrader valve that FCM uses to pressurize the dampers after they revalve them.
Basically, the sole adjustment on our FCM coilovers is via the threaded lower perches, which let you corner-balance the car and adjust the ride height. FCM's hex key adjuster is a bit fiddly but workable.
Racing Beat Tubular Stabilizer Bar
Trimming out the roll couple is a tubular front stabilizer bar by Racing Beat. It's big and red, about 3x stiffer than stock yet weighs about a half-pound less than the stock unit. Hollowness has its advantages.
The bar includes urethane bushings that are less squishy than the stock ones, which help the bar transfer load more effectively.
We currently have the stock rear bar (aka paper clip) on the car, as the roll couple in this configuration is pretty close to the stock balance.
949Racing Adjustable End Links
Speaking of stock bushings, the 949Racing end links replace the stock fixed-length jobs. That's cool since the bushings were being extruded out of our stock end links.
The metal spherical bearing eliminates a source of squish, which promises to make the front suspension react more precisely to steering inputs.
In addition, these end links allow you to remove preload from the stabilizer bar. Preload can result in uneven roll stiffness left to right and/or increase the susceptibility to brake lockup on the more loaded side.
Really, only one side needs to be adjustable to accomplish the preload removal, but there's no sense keeping a squishy stock end link on the other side. Especially since these are sold in pairs.
Cool details — each rod end has opposite threading so you can just loosen the jam nuts and turn the center turnbuckle to adjust the length — no need to disconnect the bearing ends. The conical spacers allow for maximum articulation without binding. And note the dust seals between the bearing and the conical spacers. These will help the bearings live a longer life.
Lots of impressions and track testing in the weeks and months to come. This will be fun.
Speed Source
Fixed-adjustment coilovers, MSRP $1,698
408.221.8247
Tubular stabilizer bar #54105, MSRP $150
714.779.8677
Adjustable end links, MSRP $89.95/pr
949.716.3111
I spent two days in our old-school Miata this week and was pleasantly surprised to discover that its air conditioning works as well as its new suspension. This is somewhat surprising given that the car appears to have spent its entire life thus far in a state of constant neglect. Its cruise control also works perfectly.
But, holy crap, does it ever stink in there when the top is up.
What's going on here? I removed the seats from Project Miata over the weekend to gain some headroom.
No, here the cabin is drying after I made another attempt at removing the smell that Jacquot mentioned the other day. Out came the seats (easy, five bolts each) and at the suggestion of a commenter, I carefully poured detergent-y water in and went to work with a brush, then shop-vac'ed it up.
It's better. Not 100% gone, but better.
While I was in there, I started daydreaming about having a driver's seat that's not blown to pieces like the stock one. More thoughts after the jump.
Having actual lateral support would be great. Same with a lower seating position. We'll want something that can accept a five- or six-point harness, too, for track work. And sliders are a must, since so many people drive it. Bonus: a single-piece shell seat will be much lighter (not to mention safer) than the floppy stock seat.
However, this combination is a tough nut to crack in a Miata — the stock seat is actually quite low, so sliders on an aftermarket seat usually means a higher seating position than stock, even with a seat that uses side mounts. And a Miata's sill-to-trans tunnel dimension is narrow, which creates conflict with the various wings and protuberances of aftermarket seats.
I don't have a solution for this yet. I'm all ears, though...
In the meantime, I've really been enjoying the new suspension. There's enormous grip on tap and a precision at the limit that the stock suspenders couldn't hope to provide. You might have guessed this much. However, despite the big increase in roll stiffness and lower ride height, the car's ride quality is actually compliant — better than the tired stock suspension in many ways. Less bumpstop-ridin' nonsense. Far quicker reflexes.
FCM's damping lets the suspension breathe nicely — I put a few hundred miles on the car over the weekend and never felt like I was being abused.
In fact, there's very little to complain about at all. This setup is completely daily-driver- / spouse-friendly. In short, a lot of capability has been added without disrupting the Miata's fundamental sweetness. I'm liking it. A lot.
Or a Porsche 911 Cabrio. Or a new BMW M3.
Project Miata's new suspension has given it some serious stick. The kicker? It achieves this on stock-sized tires, which are measly 185/60s on stock 14-inch wheels. Let's hear it for light weight cars, folks.
Hit the jump for the track test results.
When we performed baseline testing on Project Miata, it produced 0.89 g on the skidpad, ran through the slalom cones at 64.3 mph and braked from 60 mph in 129 feet. That was on the bone stock suspension and good summer tires.
Once we installed the Fat Cat Motorsports coilovers and Racing Beat front bar (along with 949Racing end links), we had the alignment checked and corrected as needed. It actually hadn't changed much despite the new, lower ride height of 4.75 inches front and 5 inches rear (as measured at the pinch welds).
Then we were off to the test track to confirm what our posteriors were telling us — that this is a whole new old Miata.
We didn't bother testing acceleration this time. Just handling and braking. Keep in mind that only the suspension was changed and not the tires — it's rolling on the same 185/60R14 Dunlop Direzzas as before. As per our usual testing protocol, the fuel tank was full and the spare and jack were in place.
Test Results:
Braking 60 - 0 (ft): 117
Slalom (mph): 71.3
Skid Pad Lateral Acceleration (g): 0.95
Braking Notes:
Impossible to be consistent. Very difficult to threshold brake without locking right rear tire. Strange — perhaps due to off-camber surface & stiff suspension?
Handling Notes:
Skidpad - Very neutral balance going counter-clockwise runs but far less neutral turning clockwise - just solid understeer. Still, an incredible number on stock-width rubber.
Slalom - Very stable here - better than the current model MX-5. Lithe, communicative, predictable and fun. Easy to place and easy to drive. Doesn't even mind mid-corner bumps - rare for a Miata.
It's not like I've never owned an old car before, but I find the startup "procedure" for our 1994 Mazda MX-5 satisfying on both a tactile and an auditory level. So I made a little video, completely with key fumbling because the "dome" light is in the passenger foot well. However, in retrospect, I realize I left out a key step that I always do: lower the top. Sorry.
Last night was my first night in MX-5 since it got its new suspension parts, and let me tell you, having some actual damping was really nice on the way to the ramen house. I can't wait to get this car for a whole weekend.
Scooting around in our old Miata reminded me just how right Mazda got it from the start. The Miata, especially these earlier models, is so elemental. It's clear that the focus was (and still is) on driving enjoyment. No iPod? No CD player? No problem. I didn't even use the radio as I'd much rather hear the 1.8 wind out than subject my ears to Katy Perry, Adam Lambert or a yammering DJ.
The still peppy engine pulls cleanly across the tach, the talkative steering provides more communication than AT & T, and the flickable gear shifter is so precise and perfectly weighted you'll find yourself blipping and downshifting even when you're just rolling up to a stop sign. But as anyone who's driven a Miata knows, the real fun starts when the road starts to bend. Our car's upgraded suspension and new tires felt fantastic while slicing through my favorite canyon roads.
Sixteen years old, 128 horsepower and 176,000 miles. And still a helluva lot of fun.
Not unexpectedly, Project Miata has some worn-out underpinnings. Old cars are like that.
It could be argued that this oozing tie rod end is still serviceable — hey, there's no real play in the joint, and the grease is... well, there's still grease left. But we'll use this image as a good excuse to swap 'em out with new tie rod ends from the LE / R-package cars. Slightly longer (and a whole lot fresher) than the stock Miata tie rod ends, these will reduce bump steer somewhat on our lowered car and lower the blood pressure of our Risk Management department staff.
Other preventative maintenance we'll tackle at the same time: upper control arms and new wheel bearings.
What's up with the control arms? During the suspension overhaul, I noticed that one of this car's front upper balljoints has about 1/16" of axial play. And you can hear it rattling when you drive it over rough pavement. Since Miatas have their upper front balljoint integrated into the control arm, they're not serviced separately — you simply buy new control arms when the balljoints go bad. On the plus side, the new control arms also come with fresh bushings.
A sticky-tired Miata that's driven hard (particularly on a track) will go through wheel bearings faster than do many other cars. As such Spec Miata guys are fastidious about their replacement even though they repack their bearings with high-temp synthetic grease.
Our bearings are very likely original and if so have 176,000 miles on them. They're not roaring, but Miata wheel bearings can be totally shot and not make noise. Also, determining a bearing's health using the ol' grab-and-shake-the-tire technique doesn't always work on a Miata for some reason. What you do get just before the bearings are ready to completely self-destruct is crummy turn-in and accelerated tire wear. So, while we're in there...
Project cars aren't just about mods and going fast and having fun. Sometimes you're simply dealing with the idiosyncracies of an old car.
Since the day we picked up Project Miata, its driver's mirror has been loose. Not flopping around, but enough play to where it shakes annoyingly at speed. The screws at the mirror "base" were tight as can be, though, necessitating a deeper look into the situation which didn't happen straight away. The issue was minor enough that we just lived with it. Until now.
Over the weekend I decided to fix it. Pretty simple, really. Unbolted the mirror. Saw that between the base and the door is a rubber gasket. Aha, there's the culprit. That gasket was old and flattened, giving the mirror leeway to wobble.
I just trimmed up a piece of 1/8"-thick sticky-back foam pipe wrap I found collecting dust in my garage, stuck it to the gasket — being careful not to block the little cutout that allows water drainage — and reassembled. Voila! Rock solid now.
Next up in Rattle Patrol — something is loose behind the dash on the passenger side, and it rattles obnoxiously... sometimes. Can't locate it even after removing the glovebox and poking around under there. Drives me crazy.
After driving so many new cars, it was interesting to get in a 16-year-old car. One can't help but marvel at the way we used to do things back in the day. Remember when cars had cigarette lighters and ashtrays? Anyway, I just snapped some shots of the quaint aspects of our 1994 Mazda MX-5 Miata for your perusal.
The above is a favorite feature of our Project Miata editor, Jay Kavanagh. He said that compared to modern cars that have drive-by-wire, the throttle cable made you feel more connected to the car.
To stroll down memory lane make the jump. I threw in some shots of the 2010 Mazda MX-5 for comparison's sake.
Exterior door lock: Apparently the way to lock the car, if you lock it from the inside first, is to lift that handle with your finger before you slam the door shut. Personally I hate this. Hurts my finger as I hadn't gotten the hang of letting go before impact. For 2010, you can lock or unlock the door with the push of a button on the handle.
Interior door lock: Nothing really different here. Just thought its design looked so quaint.
Headlights: Can't forget the pop-up headlights.
Audio controls: Back then six presets were all you got.
Cigarette lighter: Wow. Remember these? Now we've replaced cigarettes with another addiction: portable electronic devices.
Cruise control: In 1994, there were two places for the cruise control, here to turn it on/off and on the wiper stalk to accelerate/decelerate. And there was no "Cancel" feature. In 2010, cruise control been moved to the more convenient placement on the steering wheel.
Let's get nutty.
Project Miata generated surprising stick on stock wheels and stock-sized tires. There are a couple of problems with that approach, though.
First, there's the future — the stock wheels' snug dimensions severely limit our options for brake clearance, and those skinny tires will be hopelessly overwhelmed once we finally get some power in this thing. Second, the car had all the visual impact of a Vern Troyer roundhouse to the temple.
The addition of 949Racing 6UL wheels changes all of that.
A few years ago, Miata owner Emilio Cervantes observed a dearth of performance-oriented wheel fitments available for his car. He wanted a strong and light 15-inch wheel but was frustrated by the fact that rarely did they stray wider than 7 inches. Rather than gripe about the situation, he took the initiative and made the damn things himself. Thus the 15- by 9-inch 6UL wheel and 949Racing was born.
These low-pressure cast aluminum wheels are manufactured exclusively for 949Racing by a supplier of forged wheels to OEMs. Emilio acknowledges the benefits of forging in producing a stronger and/or lighter wheel. The cost, however, would have been prohibitive. Besides, these 6ULs weigh just 12.8 pounds apiece according to our scale, so we're not complaining. Stock 14-inch wheels are about 12 pounds.
You might be able to see that the tires — 225/45 Hankook Ventus RS-3s — are modestly stretched on the 9-inch wheel. The idea of running a slightly wider wheel than usual is to remove sidewall flex in order to enhance transient response and provide more uniform tread loading.
Visualize what happens when you're cornering hard — the force at the contact patch puts the sidewall in tension. If you have a narrow wheel, the outward-bulging sidewall needs to be contorted quite a bit before cornering forces can build in earnest. The more sidewall deformation required, the longer the delay in the tires' ability to respond to steering inputs.
All else equal, the slight stretch provided by a wider wheel applies a bit of preload to the sidewall, which quickens its ability to react. Less time is spent taking up the slack in the sidewall, so steering response becomes more linear and direct. This strategy of removing sidewall compliance also makes your camber settings more effective. It's like plus-sizing the wheel without actually increasing the wheel diameter.
Like anything else, it's best to use this approach in moderation. At more extreme wheel-to-tire width relationships than we have, there's a higher risk of de-beading the tire if you simultaneously hit a sharp bump during hard cornering. Don't go copying Keiichi Tsuchiya's setup on your street car.
This is just about the widest tire you can fit under a Miata without getting too crazy with the fenders or with wheel offset. With only a flat-roll of the fender lips using a fender roller borrowed from our friend Steve Mitchell of M-Workz fame, we were done. The big tires fit with just a slight rub to our biggie-sized Racing Beat front stabilizer bar when at max steering lock. We can live with that, but to be fair, Emilio recommends his 6ULs in 8-inch width for Miatas that are exclusively street driven and won't be generating more than about 225 whp or so. This should also give you some idea of where we want to go with Project Miata.
Wheel offset is 36 mm compared to the stock 45 mm, which means the centerline of the wheel has moved outboard. This widens the car's track ever so slightly and increases scrub radius. We'll be sure to share impressions on what, if anything, this changes in terms of steering and handling.
To be sure, Project Miata has a truckload of visual attitude now. By looking at it you might even think it has enough power to get out of its own way. All in time.
Speed Source
15x9-inch 6UL wheels, MSRP $189/ea
949.716.3111
I'm happy to say it drives about as good as it looks. Yeah, I happen to like the dents; they make it look like a tough little bastard.
Anyway, apart from the driver's seat bolster, which looks like a popped bratwurst, and that smell, the only complaint I have is the steering wheel, which is too low and prevents me from heel/toe shifting because it presses down on my right leg. Our Miata Meister, Jay, has hinted that a smaller steering wheel has been considered, along with some seat modifications as well.
Shut up and tell you how it drives? Fine.
With the trick new suspension and more aggressive wheel and tire package, I expected a tramlining, bouncy nightmare. But Jay has apparently thought this through because the car's good traits have merely been enhanced. The car gives you great feedback and the damping is more or less spot on. Honestly, the only problem now is not having enough power to overwhelm the cars considerable level of grip.
I was let in on the power plans for this car, and while I don't want to divulge the exact specs or architecture of the new motor, I will tell you it involves pistons.
I usually don't have a lot of patience for gimmicky door handles, but the dainty handles on first-generation MX-5s get my approval. Opening the door with one finger is just cool, and I like how the mechanism is damped. The door feels just right when you open it and sets the stage for driving this entertaining little car.
Any other door handles out there that you're smitten with... either for their cool design or ergonomic awesomeness?
Our 1994 Mazda Miata started going mildly haywire a few days ago. All of the gauges went kaput, save for the cable-driven speedometer. The turn signals ceased signaling. Michael Jordan resorted to using the trip odometer to decide when to add fuel over the weekend.
This morning I crawled down by the pedals to have a look at the interior fuse box — the one that's located on the kick panel in the neighborhood of the hood release lever and the driver's left foot.
But the cover and it's all important fuse diagram were missing, so I referred instead to the one on my own personal 1991 Miata, currently in a state of partial disassembly in my garage.
The fuse box from my own Miata clearly indicated that the 10-amp "meter" fuse is the second one over from the upper left-hand corner. The lead photo shows what that fuse looked like after I pulled it from our project car. But something else wasn't quite right, and it may indicate a larger problem.
The fuse that popped was a 15-amp fuse, not a 10-amp fuse as the diagram stipulates. I guess it's possible that my 1991 Miata with its 1.6-liter engine takes a 10-amp fuse and this 1994 with a 1.8-liter motor takes a 15-amp fuse, but I somehow doubt it. The gauges and interior accessories are identical to my slightly older car.
More likely, the 15-amp fuse was installed because that's the size of the single spare fuse that's provided in the fuse box cover.
But if a 15-amp fused popped where a 10-amp fuse is specified, we've got some sort of latent electrical problem somewhere. Heck, we've still got a problem if a 15-amp fuse popped where a 15-amp fuse is specified.
I didn't have time to sort any of this out this morning so, like someone before me, I installed the spare 15-amp fuse from my car's fuse box cover.
The gauges and turn signals work fine once again. Jay loves solving electrical puzzles like this, but he's away on a business trip. I'll save it for him. He'll really appreciate that.
I know how much you like my pink striped beach towel as a backdrop for Mazda Miata component photographs, so I'm pressing it into service once more. I like it so much that it's in my rag bag, the place I go when I need to sop up spilled motor oil.
The above bolt is one of four that holds a pair of convertible top clips to the top of the Miata's windshield header. But this one is not from our 1994 Miata project car. No, it's a spare I had lying around in my garage.
Why does this matter? Our '94 has worn header clips. The grooves that the convertible top latches fit into are worn, and that means the top is hard to latch down properly. In fact, it recently came loose at speed.
So I figured I'd swap the worn latches out for my pair of "barely used" spares. But the bolts in question take a T35 Torx bit and I can't get them loose. T30 is too small, and T40 won't fit. I have no idea how I removed this one 19 years ago, but its mates are thoroughly stripped out so it must have been sketchy.
If this sounds familiar, it is. Our Ford Flex's front brake rotors need a T35 Torx bit (Ford swears we're wrong, but my ill-fitting T30 and non-fitting T40 bits say otherwise). The Flex rotor replacement wasn't critical, so I hadn't yet bought this inexplicably hard-to-find tool while I waited for a hole in my schedule.
Eazypower.com has tons of T35 Torx bits listed on-line, but their security certificate has expired and my browser throws up huge warnings. Sorry guys, but I'm not going there.
So I ordered one from someone else on Ebay. I'll fix the Miata and the Flex as soon as the stars align and I receive this much-needed tool. Stay tuned.
A lot of car people really admire the original Mazda Miata because it's such a simple and well-executed design. But there are also those who'll never get it. I heard one myself last week while I was driving our '94 Miata with the top down: "Look at that. That car is so bleeping blay."
Whatever, dude. I call I can say is you're missing out. He probably assumes it's front-wheel drive, too.
Let's move along. I'll point out Jay's bolt-on mods along the way.
The secret of the Miata's success is the fact that it is, in fact, a lightweight rear-drive roadster with double wishbone suspension.
A heavier L-shaped lower arm (yellow) handles the bulk of the suspension loads, and a lighter A-shaped upper arm (green) helps define the steering axis and the caster and camber angles.
Because the engine drives the rear wheels, there's room for a front-mounted steering rack that's mounted ahead (white) of the front axle centerline. Steering precision benefits as a result.
The original springs and shocks were coil-overs too, but the lower spring perch was welded in place and the springs and shocks were considerably softer. I measured the springs on my 1990 Miata once, and they came out at 130 lb/in. These springs are considerably stiffer at 425 lb/in. Part of the increase provides a sportier ride via a higher ride frequency. But there is a practical aspect, too. If you lower a car, the springs must be stiffer in order to absorb the same amount of energy over a shorter distance.
The yellow Bilstein shocks are monotube units, whereas the original dampers were a twin-tube design. As the name implies, monotube shocks are made of a single tube, and that allows any internally-generated heat to wick out easily. Twin tube shocks have a tube within a tube, and that makes them store heat, like a thermos bottle. It also makes for a smaller diameter valve because it runs in the innermost tube. Both of these factors, taken together, limits the amount of damping they can produce without fade.
Here's another view of the upper and lower arms.
The outer ball joint (black) is easily replaceable because it is bolted on to the end of the lower arm.
Here's another view of the L-shaped lower arm. Both inner pivots (yellow) are made up of eccentric cams.
Good news: camber and caster are both adjustable.
Bad news: it's a pain in the butt to adjust because each affects the other. Loosely speaking, the front one primarily affects camber and the rear one primarily affects caster. Also, the pivot bolts aren't particularly huge. If you run over an apex curb on a track day, things can move and your alignment may readjust itself to a setting you'd rather not have. Same goes for potholes.
Here you can see one of the potential pitfalls of aftermarket coil-over springs with adjustable spring perches. Springs flex a little to the side as they compress, and the outside diameter of the threaded collar can be somewhat close to the inside diameter of the spring.
These rub marks (green) tell the tale. You can hear it, too. Some aftermarket spring sellers (Ground Control comes to mind) offer barrel-shaped springs that provide clearance in this critical area. The rubbing and the noise isn't a huge deal for a race car (my Miata rally car squeaked like you wouldn't believe), but it's less than ideal for street coil-over applications like this.
A much larger Racing Beat stabilizer bar has been fitted, but it bolts into the stock location. A larger bar requires a larger bushing to pivot in, and the red color of this one indicates that it's urethane, not rubber.
This stab bar is hollow to save weight, but that doesn't affect its torsional stiffness as much as you'd think because the outer extremes of the cross-section is where most of the work is done. The torsional stiffness of a stab bar is proportional to its outside diameter to the FOURTH power (OD^4). The torsional stiffness of a hollow bar is proportional to OD^4-ID^4
Our old stock front stab bar was 19 mm in diameter — about 0.75 inches. This racing beat bar is 1.125 inches in diameter on the outsdie and 0.875 inches in diameter on the inside. Do the math using the fourth power of those diameters and you'll see that this stabilizer bar is 3.25 times stiffer than the stock unit.
You can actually see that it's a hollow bar by the way it looks at the end where it's squished flat. For the record, Racing Beat says it weighs 5.5 pounds.
The original fixed-length stabilizer bar links have been replaced here by adjustable ones. But you don't really need to adjust something like this.
The idea behind them is that fixed-length links might lead to a little stabilizer bar preload. That's no big deal on the street, but it can matter on the track. So what you'd do is get the car set up and aligned, get the driver and the fuel installed and then have a friend or crewmember adjust the length of these links to remove the preload. One of the heim ends is left-hand thread and the other is right hand thread, so you don't need to remove them for adjustment. Simply loosen the thing jamb nuts and then twirl the black center section to the desired length.
If the word "crewmember" doesn't apply to you then the word "adjustable" probably doesn't either.
However, the fact that these links have spherical heim ends instead of rubber bushings is something a street enthusiast might appreciate.
No, "R" isn't for rear. There are the stock right-front brake calipers on our Miata. They're single-piston sliding calipers and cast-iron ventilated rotors. Simple, but very effective. Easily upgraded for track use with aftermarket pads.
Our back, the first-gen Miata has another pair of upper and lower wishbones. And we've got another colorful coil-over replacement, too.
Like the front, the lower arm is the higher-stressed one that does most of the heavy lifting. By the look of it, the spring/shock arm ratio might be 0.80, but its lean angle takes some of that away. The tiny paperclip of a rear stabilizer bar (yellow) operates at something like a 0.60 motion ratio. We haven't upsized this one yet because the car feels balanced as it sits.
But it looks like we could trim the ends off those stab link bolts to save some weight. :)
There's nothing much to see here but 177,000 miles of baked-on road grime.
Another lower control arm, another pair of alignment adjustment bolts. Move these to adjust camber. Make sure they're tight.
My 1990 and 1991 Miatas did not come with these braces, but our '94 came with them stock. I think they were added whan the engine size was upped from 1.6 liters to 1.8 liters. Whatever, they're a good upgrade to consider.
The lower arms connect to horns on the rear sub-frame that hang down. The longitudinal braces (yellow) tie them together and to the unibody, and the later one (green) stiffens things up side-to-side. Since most of the lateral suspension loads go through the lower control arms to these horns, these stiffening braces are potentially huge if you add lots of horsepower and lots of tire, like we plan to do.
Braking duties are carried out by single-piston sliding calipers and solid cast iron rotors. The calipers and pads are the same as my 1.6-liter car, but the rotor diameter is larger, and the larger moment arm that represents allows them to apply more torque.
This is probably the lightest wheel/tire combo you're likely to see on stock wheels, and the low unsprung weight they represent is another secret to the Miata's success. That's what you get with 185/60R14 tires on light 14" factory alloys. The larger 949-Racing 9x15 wheels we've put on since are supposed to be no heavier than the stock wheels here. With tires, who knows? We'll see.
When I had our 1994 Mazda MX-5 Miata for the weekend I was already well aware of the fact that 2nd gear needs to be babied. Correction, I forgot at first and then was promptly reminded when I was leaving our garage Friday evening. From then on, I tried oh-so hard to baby it. But still, there were times when the car was not ready to be upshifted and it would emit that nails-on-a-chalkboard grinding noise. Argh!
And for the rest of the weekend, every time I went to upshift to 2nd gear I found myself gritting my teeth in anticipation. So frustrating! Especially considering that usually I love blasting off the line from a stop. But, nooo, had to take my time with this one. That meant I couldn't be faster than the typical sleepy Angeleno driver.
Merging onto the freeway, I usually exploit my fellow drivers' slow reaction times to squirt past them, but couldn't do that here. And ended up being stuck in the wolfpack most of the time. Only cutting and thrusting through small openings and holding 1st gear longer than usual.
Project Miata guy, editor Jay Kavanagh, said that "even though this gearbox can be repaired (bad 2nd gear synchro), we have another one waiting in the wings." Thank gawd, because there's nothing more annoying than driving a car that needs to be driven briskly but...can't.
Just checked the old Miata's oil and it was down a quart. So it seems to be using/losing a quart every 1,400 miles or so. Granted, it's got nearly 180k on the clock so I'm sure it's burning a little (though we see no smoke out the tailpipe) and Jay Kav told me it has a nasty front cam seal leak. Of course, this malady will be taken care of as we continue to improve this scrappy little go kart.
The Miata and I spent some quality time together yesterday — an hour of pokey movement on clogged Los Angeles streets and then another 250 miles of highway travel. How was it? Oh, allow me to fill you in, dear reader.
If you haven't ever been in a well-used Miata like this, the best I can equate it to would be flying in a commuter prop plane. You've got a cramped interior, a bumpy ride, a flexible chassis, a lot of noise and near non-existent crash protection. Did I mention noise yet? First, there's the Miata's engine, which at highway speed sounds like this: Beeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee. Actually, the interior noise has more to do with the two holes in the Miata's top that are big enough to see daylight through. Talk about a wind leak.
Furthermore, I suspect one of the wheels is out of balance. Starting at 65 mph and up to about 75 mph, the steering wheel vibrates. Every time I was accelerating, I thought of Chuck Yeager approaching the sound barrier — do I press on through or back out? Or, translated, do you want to drive at 63 mph on the freeway (where the Miata is actually in its comfort zone but the speed limit is 70 mph) or punch it up past 75 where the car feels like a can of soda shaken a few too many times? Don't bother with the radio — you can't hear it.
Now, don't get me wrong here. There are certainly far worse methods of transportation to spend five hours in. The A/C still works. So does cruise control. And heck, it was actually kind of fun to drive something that's not brand new and $40,000. Character: our Miata has that in spades. I'm looking forward to spending some time with the project Miata during the next two weeks.
In last week's post about driving our Mazda Miata on the highway, I mentioned that I thought a tire was out of balance because of a vibration coming through the steering wheel. We had the new tires balanced when we had them mounted, but apparently Miatas are very sensitive to even slightly imbalanced tires. So editor Jay Kavanagh (who's overseeing the Miata project) suggested getting a "road force" balance. A few commenters on that post also suggested the same thing.
So I tracked down a shop (my local Tire Pros) with a road force balancer by using this site. As the description reads for the Hunter GSP9700: "[It] solves wheel vibration and tire pull problems that other balancers and aligners can't fix."
You can read all about it on the site, but basically it simulates actual road force on the tire by applying pressure from a rotating drum and takes more measurements than a regular balancer. Near as I can tell, it's like the A-Team — "If you have a problem, if no one else can help, and if you can find them, maybe you can hire the GSP9700."
Oh, nearly forgot — yep, two tires required further balancing. Total cost was $64. And after a brief drive on the freeway, it seems like the steering wheel vibration has been cured.
You're not going to be fitting a whole lot of luggage back here, but for daily use the Miata's trunk works out alright. I stuffed in some reusable grocery bags yesterday without much effort. The Miata's spare tire takes up some valuable room but I know of other Miata owners who have relocated the spare to underneath the car. Oh, and our car's trunk lid was squeaking and not really opening freely — I lubed the hinge points with some silicone spray.
Now that the tires have been balanced for real, it's time for us to get the car properly aligned and corner-weighted. But even in its less-than-ideal state, the Miata has amazed me with its grip and nimbleness. I've only briefly driven it on a curvy road yet just from this I can tell it's got mad handling skills. I turned into some corners with what I thought was a fairly aggressive speed and by the end of each one I came out realizing that the Miata had plenty more to go.
In today's world where a 3,300-pound sports car is considered light weight, it's a revelation to be piloting one that weighs just 2,300 pounds and rides on super-wide tires. Plus, it's nice not to feel intimidated in a way you might get when driving a super-sticky (but super expensive) sports car like a new 911 or GT-R. This project car is only going to get better.
Yep, the first-generation Miata is pretty small. And it feels really small when you're boxed in on the freeway by a brace of trucks. It can seem like you're one truck driver's sneeze away from being in your own personal trash compactor.
While I'm on the topic, I might as well mention the sense of limited crash protection I get while driving the Miata. I was on the freeway recently when traffic suddenly slowed down. I was able to slow the Miata down properly. Then, you know the drill — you watch the rearview mirror as it turns into your own personal suspense movie. Is that car behind me going to stop?
Fortunately, the Toyota RAV4 behind also slowed down. Traffic ahead of me relaxed a little, so I put a bit of space between the RAV4 and me. But then I heard screeching tires and watched in the mirror as a blue Ford Mustang didn't stop in time and slammed hard into the back of the RAV4. I hope both drivers were OK. But I'm really glad that RAV4 was there. If the Mustang had rear-ended our Miata, it would have been dire.
OK, sadly this post has nothing to do with Batman but does have to do with our 1994 Mazda MX-5 Miata's soft top. Since we lucked out with a couple of sunny days last week, I gladly took our Miata for a spin. But since our beat-down soft top is getting rattier and more delicate by the second, it turns out the stress of simply putting the top down and then back up has torn the holes wide open. Check out that gaping beauty over the rear window. Suffice it to say that taking it to a car wash would result in a very damp butt.
Fortunately Project Miata editor Jay Kavanagh will be shopping for a hardtop this weekend. Fingers crossed. By the way, anyone (preferably in SoCal) have a hardtop they wanna sell?
Maybe if our long term 1994 Mazda Miata were a 1990 Mazda Miata, maybe I could have taken it directly home last night instead of having to come back to our offices after I met some friends for dinner.
See, the rub is that I have my laptop with me virtually all the time. And the Miata doesn't have a roof. And even if it did, who cares, that wouldn't keep anyone out who really wanted a slick new (not so much) computer. So what, right? Dump it in the trunk. Right?
Not so fast. See, for 1992, Mazda added a trunk release button to the center-console of the Miata. While that little bin does, in fact, lock, saying it's safe is like saying your sister's diary with its lock was safe. Pretty much, if you have fingers you could pry that box open. That's assuming the one you're dealing with isn't broken. Ours is broken. The slot the metal tab fits into is sort of jacked up and doesn't hold tight.
So the options were: Take my own car. Risk it. Come back to the office and pick up my stuff once I was done street parking.
None were ideal as I really do enjoy driving this Miata and wanted to take a drive up the coast later that night — Top-down, heat on — I'm rallying against Jay's desire to ruin the open-air feel with a hardtop. It's not a racecar, I vote to keep it a roadster.
Maybe I'm getting soft, but it seems to me that if you're going to have a soft-top, access to the fixed and locked part of the vehicle should not be a box-cutter away.
Wide rubber has added a lot of precision during hard cornering in Project Miata, our 1994 Mazda Miata, as well as providing some seriously beefed-up looks. I anticipated some additional impact harshness from the shorter, more taut sidewalls, too, and they delivered.
After driving it extensively with the big rolling stock, it has become apparent that chassis stiffness is an area of opportunity.
Being a convertible, the Miata chassis is pretty flimsy — the real roofs of fixed-head coupes add a whole lot of structural rigidity. And our car's wider tires, being in contact with a larger proportion of the road surface, transmit additional inputs that the suspension cannot damp because the chassis throws in the towel first, quivering and shuddering in response. Then the floppy softtop gets in the act, too, doing some shimmying and shaking of its own.
Making the chassis stiffer would allow the suspension to do its job better, which is goodness on all fronts of the ride and handling equation.
A rollbar is a good start. A rollcage would do wonders for stiffness but is totally impractical for street use. More elaborate underbody bracing wouldn't hurt, but doesn't 'close the box', which is where the real gains are to be had.
Really, the car would be best served by bracing that ties together the two disparate ends of the vehicle. Namely, the front and rear bulkheads. Whenever I drive Project Miata now, I've got door bars on the brain.
This morning I shot this video of our Miata's ginormous old-school pop-up headlamps. They're so tall that when you flip them up you can feel the car's aerodynamics change. The Miata's wind noise levels with the top up and its wind management with top down are completely different when the headlamps are up.
They're so tall I decided that the above video didn't cut it. I decided you needed something in the frame for scale if you were to completely understand just how stupid big those headlight doors are. So I shot another video and used my shoe (Size 10 1/2). You can watch it after the jump.
We all warn one another about driving the Miata. After all, it is, as Champ Car driver Paul Tracy so eloquently once described the cars of his rivals in the Indy Racing League, a crapwagon.
It crashes, rattles and shakes. It gasps, squeaks and moans. The seats are torn and so is the top, and the only good thing about the top occasionally losing its grip on the windshield header and flying open at exactly 54 mph is that it smells so bad that the fresh air is a relief. There's even the 24 Hours of LeMons sticker on the driver side window to remind you just how close this car is to scrap.
But as a guy who drove a car like this back when they were new and has experience in plenty of used examples, both street cars and race cars, let me tell you that every one of these first-generation MX-5 Miatas is like that.
Much of this we interpret as the creeping influence of entropy on this car, a sense that the weakening gravity well that still holds the car's components together after 179,769 miles will suddenly lose its force and the assorted bits and pieces will simply float off into space from lack of interest. But you should know that the MX-5 was always no more than a rumor of a car to begin with.
It's tighter than the Lotus Elan after which it was patterned, since it has a real unit-body monocoque instead of a slim backbone chassis, but the Miata still flexes and twists like any car without the structural reinforcement of roof. The suspension is meant to ride on the springs when you're driving down the freeway, but as soon as you get more than an inch of lean going in the corners the car is settling into its tall bump rubbers, which really provide the springing medium, as if you were driving some kind of Formula 1 car from the early 1980s. And while people here complain about the tiredness of an engine and gearbox that have miraculously survived 179,769 miles, the truth is that the engine runs smoother and the transmission shifts quicker than plenty of examples of this car that have half as many miles.
Of course the second-gear synchros in every one of these first-generation Miatas have been toasted by exactly the same kind of guys here who complain that you have to take the shift lever across the gate and then back again in a kind of double-clutch move to make all the gears line up in a happy way before you can get a clean shift into second.
But what I'm really trying to say here is that while this car might look pretty troubled in a cosmetic sense, it's really not that bad. The Mazda MX-5 Miata has always been an acquired taste, and this car just reminds me that I still like all these cars a lot. I'll never get to own a Lotus Elan 26R like the ex-Jim Clark car now being raced by my friend John Delane (pictured above), but this is close, even if it looks like a crapwagon.
The other week I noticed that Project Miata's radiator fan was cycling on and off erratically. Opened the hood. I put a finger on the fan relay. It was clicking over indecisively as if possessed — so the fan was doing what it was being told, but it was being told wrong.
There isn't much to the cooling circuit. The ECU commands the fan relay based on advice from a coolant thermosensor.
Of those three components, the relay is the most likely to crap out. I theorized that the sporadic clicking is the relay in its death throes, and that soon it wouldn't function at all. If/when that happens then the fan won't run and engine go boom.
Short of time and feeling frisky, I ordered a new relay and popped it into the fuse box this morning. At five bucks, the stakes were low. Went for a quick spin and... no difference. Time to find my multimeter.
Finally got around to getting in our Miata project car. It's been in and out of Jay's hands most of its time here, so I figured I would just wait until it had a good chunk of its work done before trying it out.
What surprised me? It's a roomy little sucker. I'm 6'2" and I fit in this Miata just fine. It has a good driving position and the seats are decent given their age. Drives pretty solid too. Good clutch take up and a easy to row gearbox. Yeah, there's not much power, but the engine is willing to rev without threatening to throw a rod.
Jay's suspension mods feel fine to me too. Yeah, it rides pretty firm and all, but there's enough give to make it bearable. Looking forward to getting it on a real road and sampling the stick of the big Hankooks. No doubt they look tough on the new wheels. All in all, a pretty solid ride given what we paid. Can't imagine finding something more enjoyable for the money.
It turns out that cars with a lot of miles often have keys with a lot of miles.
See that fatigue crack in Project Miata's key? Yeah. There's one in the same spot on the other side, too. The key's also got a twist in it along its length (you can see it if you look closely) and you can easily bend it using your fingers. It's now so easily tweaked that it wouldn't work in the ignition yesterday without some finessing.
Okay, I admit that this isn't at all exciting. But that's kind of the idea — it could have ended up exciting in a real crummy way. A couple bucks at a local locksmith got us a duplicate key and avoided potential breakage in the ignition cylinder, which would have sucked big time. If you wheel an old hoopty, take a moment to check your keys.
You know why I got our Project Miata this weekend? Simple. Nobody else wanted it.
But for a select few, most of the staff doesn't want to spend a weekend driving around in a quivering, mildly busted up project car. Me? Well, I kinda like it. As fun as the finished project will be, it makes it so much more interesting to watch and drive the car as it makes its progression from beater to track star. You get to see how each new part and upgrade affects the performance and the character of the car - assuming you don't drop a suitcase full of money and have it all done at once. Part by part and piece by piece, you see the car change and develop.
I'm getting to know the car pretty well at this stage and I'm sure that will only help me enjoy the car more throughly after it's done - assuming everyone will pass it up and let me drive it again.
Last night was my first time behind the wheel of our project Mazda Miata. I owned a white 1992 Miata, but it's been years since I've driven the little convertible. I sold my car in 1997, and can't remember the last time I had the opportunity to drive a more recent version.
Our '94, beat to hell with its ripped top and shredded seats, filled me with immense joy. I was happy to use a real key to lock its fobless doors, to watch its pop-up headlights illuminate the night sky.
I love this car. I can't believe I forgot how much I love this car.
You can't see it well in this photo, but our long-term 1994 Mazda MX-5 Miata has a new top. It's black, and yes, it's a hardtop. Jay will tell you the particulars about the acquisition and installation of the hardtop in a subsequent blog entry.
For now, I'll just offer a few impressions from my 50-mile overnight visit with the car. To start, our MX-5 absolutely needed a new top. The soft top had begun to self-destruct, as you know, and it leaked water and sometimes came unlatched on the freeway.
In contrast, the new hardtop fits snugly. Top-up visibility is vastly improved. And we now have an extra storage area where the old soft-top mechanism used to be. On the flip side, that new "open hatch" area creates a booming resonance on the freeway as sound bounces off the sides of the hardtop. Oh well. It's still quieter in here than it was under the old soft top; we'll take some decibel readings for you at a later date.
I didn't really miss being able to put the top down while blasting down the freeway at night. But this morning when I walked outside and saw this sky, it bummed me out a little. I took a drive down the coast from Big Sur to Cambria, California, last weekend in a Z4, and the setting sun and salt air are still fresh in mind.
Obviously, the Miata's hardtop can be removed — we just can't do it on the spur of the moment anymore. I crave that spontaneity, so if I bought a personal Miata, it would have to have a soft top.
As Erin indicated, last week I picked up a Craigslist hardtop for Project Miata and ditched the blown-apart softtop. It's now a step closer to a true coupe, which is a variant of the Miata that Mazda should have made in the first place. I'm no fan of ragtops for reasons I've mentioned previously — in my opinion, Miatas are good despite their folding roofs, not because of them. But you know what they say about opinions.
Two protruding studs at the rear deck ("Frankenstein bolts," as they're known) align the hardtop's rear seal, while two latches at the windshield header and two more at the base of the b-pillar do the heavy lifiting in securing the hardtop to the car. That is, if your Miata has side striker plates which this one does not. No matter. For additional security I picked up some Spec Miata brackets and bolted that sucker down.
The hardtop was not designed to be chassis-stiffening item but it does provide some additional structure by "closing the box," tying the two discrete ends of the car together. It's a difference you can feel when you drive over bumps. The car drives more "all of a piece" now. There's still a lot more chassis stiffness to be had — NA Miatas are flex machines — but the hardtop makes a difference you can notice.
There's noticeably less drag at freeway speeds too, and external noise is quelled better, though the hardtop tends to amplify interior noises. Weight-wise, it's about three pounds heavier than the softtop + now-useless brackets, bolts and claptrap that held the softtop in the car.
I'm digging the hardtop. Looks cooler, too. (Sorry the photos are sort of grainy; was using an unfamiliar camera.)
The seat is tearing apart and the pedal covers are falling off, so why did I enjoy driving the Miata so much last night?
The light traffic on Sunset certainly helped, but it was mostly because I found that this two-seater is shockingly comfortable for my 6'2" frame. I don't even have to put the seat back all the way. The spacious foot box helps too as you're not forced to constantly shift around to keep your feet properly aligned.
Yes, getting in and out is a bit comical, but no more so than our Viper. And that car feels claustrophobic compared to the Miata. Never would have guessed that from the outside.
We knew the second we put the wheels and tires on our super-long-term Miata that it was the right choice. Even if they made the car ride like a Delorean they were worth it for looks alone.
After putting some additional miles on it over the last week or so I don't think they're problematic at all. Sure, the ride is a bit firm, but that's as much the suspension changes as anything. I don't get the sense that they're too big or too heavy for this car and the grip is just nuts. I'm still looking for a good fast turn that will push them to their limits. I think it might take awhile.
Are sunny days sweeping the clouds away? Even if they are, I couldn't really enjoy them now that our 1994 Mazda Miata has a bolted-down hard top. Pout. Project Miata editor Jason Kavanagh definitely has a different idea of what makes a fun drive. He of the Angeles-Crest-blasting, canyon-carving, Lemons-racing variety while I like leisurely drives around town on my Vespa...OK, I lie, I like taking corners fast, too (though not on my Vespa).
But I do have to say, now that I don't have to worry about the soft top flying off of our crapwagon, I can kind of see JayKav's point. Sure, the enclosed quarters of our Miata feel especially claustrophobic on a beautiful day, but this car is now so focused I can almost forgive him for taking away its top-down spontaneity.
On another note, I FINALLY got the hang of that 2nd gear. The trick is to place the gearshifter in 2nd, not shove it. This has made my time in the Miata even more fun and stress-free. Oh, and bonus? It's perhaps the only long-term car I can park in my new garage without fear of scraping the sides. I want to drive it again!
OK, I don't doubt that you all already know what a hard top looks like but check it out in our 1994 Mazda Miata. The visibility out the back is now teh awesome. No more tiny, swaying window to look out of but this huge expanse of glass and, look, there's even a shelf back there for my purse.
Here's a view of the rear via the rearview mirror.
Of course this inspires confidence when getting around slower cars.
It's a half-day for us today before the holiday. So, let's try something different. Instead of the caption contest, we offer this photo.
Make up a story about this picture in 50 words or less. Be creative. Tell me a story.
One quart every 1000 miles. That's the rate of Project Miata's oil consumption.
Judging by the extra glossy block, accessories, splashpan, subframe and steering rack, some of it leaks out the cam seals. The rest is being burned off in the catalytic converter.
This engine is not long for this world.
Recall a while back Project Miata's cooling fan was operating erratically. It's now fixed (I'm pretty sure).
The short explanation: replacing the coolant thermosensor at the back of the head did the trick, as expected.
For those curious / bored readers, the resolution entailed some other cooling system shenanigans as well. Okay, the whole process sort of turned into a goat rodeo. Click on to read the long and twisted saga.
After replacing the relay, my next plan of action was to replace the thermosensor. I should have kept my eye on the ball and just done that. Instead, I got distracted.
A friend had a fancypants aluminum race radiator left over from a customer's Miata project car. It was removed simply because the customer is one of those bigger-is-better guys that always wants the latest thing. Whatever, he didn't need it and gave it to me. Used for only a short time, the radiator was in surprisingly good shape, plus was made by a reputable big-name manufacturer and not some chintzy Chinese off brand.
Perfect, I thought. We'll be adding power, so some extra thermal capacity is a must. I threw it in Project Miata and even sealed it up nice with a bunch of foam strips so that all incoming air goes through the radiator (and fans) rather than around it.
The next day while commuting to the office, the temp gauge started to climb.
Now, if you're familiar with factory temp gauges, you know that they are essentially worthless. They're highly nonlinear, meaning they sit in one happy place over an absurdly wide temperature range. This is because most automotive consumers suck — when they see a temp gauge move around, they freak out.
In response, manufacturers have over the years "deadened" their temp gauges so that their needles hardly budge even as coolant temp varies widely. This comforts the lowest common denominator customer into thinking that everything is just peachy but makes for a less-than-useful gauge. This, of course, sort of defeats the purpose of the gauge.
To wit:
"Your engine is stone cold." "Your engine is about to blow up."
Okay, slight exaggeration, but the point is if the needle in a Miata moves off this 11 o'clock happy place over to 1 or even 12 o'clock, it means that things are getting crazy hot — I confirmed this years ago by comparing to an actual, real temp gauge with actual, real numbers.
blasted the heater to bleed off some heat from the cooling system and starting driving like a sissy. The needle recovered.
One of the golden rules of working on cars is if something goes wrong immediately after you made a repair, it's certain to be related to the work you just performed. I call this The Bonehead Rule. In this case, the hot running was very likely related to the radiator swap — it may be a big 'ol air bubble trapped in the cooling system, or a coolant leak somewhere or the radiator cap wasn't seating correctly in the new radiator which would mean it wouldn't hold pressure and would puke coolant into the overflow bottle.
However, none of those things applied — burping it did nothing, all coolant was present and accounted for, the fill level was right where it was before and the cap was holding pressure.
Huh. Well, I guess our fan issue is getting worse, then, I thought. Better jump on that.
So I did. But before I did, I let the car idle in my driveway to test the theory that the erratic fan would cause a thermal runaway. Oddly enough, the fan — being erratic — didn't operate erratically at all during this test. It switched on and ran without a hiccup. Yet the needle marched over towards the hot zone of 1 o'clock. Now this is weird.
Some probing with an infrared thermometer suggested that the thermostat wasn't consistently opening fully. The notion that another component not directly related to the work I'd just done could fail so coincidentally went against my better judgment (I'm an adherent to The Bonehead Rule), but thermostats can fail in many ways, and this is one of them.
I'd never replaced the t-stat in this car, and it's always a good idea to do so in an old car, especially one with an unknown service history. Besides, it's dead-easy to change a Miata t-stat. Less than a twenty-minute job start to finish, without trying hard.
I did so, and also changed the thermosensor.
This guy is located waaaay at
the back of the head, buried beneath the ignition coils and crank angle sensor.
At some point I'll do a coolant reroute, but that's a topic and installation that will wait for another day. All in time.
Once those bits are out of the way, it's an easy 19mm zippywrench to change the thermosensor.
All buttoned up. Warm up the engine. T-stat opens nicely and we're getting more heat at the top radiator tank now. Good. That's progress. Fan comes on smoothly, no erratic nonsense. Great.
Now let's see if it can actually control the coolant temperature..... and that's a big no. Temp gauge still climbs at idle. Even with an additional squirrel-cage fan blowing air into the car's mouth, the car's cooling fan never switches off — it simply can't shed enough heat to bring coolant temps in check.
Yeah, remember that bitchin' aluminum radiator? Not so bitchin' after all. It was used, so it may not be representative of new. Perhaps internal passages were plugged. Dunno. Couldn't see anything awry peering into the top tank but who knows. Whatever the case, it sucks.
Re-swapped in the original old stock radiator (it's the slightly larger one from an automatic Miata) and everything works as expected — the fan can now actually bring down coolant temp, and it switches off after it has done so. Finally, a normally-operating cooling system.
It's still woefully undersized for the demands of future actual power, but it's good to know we've got the basics of our cooling system sorted out.
As for that race radiator, it's found a proper home.
This won't be nearly as cool as one of Dan's Suspension Walkarounds, but what the heck. I had both of Project Miata's thermostats (the old and the new one) in hand during my cooling system festival and saw some notable differences.
Maybe you'll learn something from this. Perhaps not. In any case, here goes.
Right away, it is clear that the old aftermarket t-stat is missing a sub-valve. But what the heck does this do?
A sub-valve is a mini thermostat. Its purpose is to compensate for any lag in the main valve's ability to respond to temperature. The main valve can't open and close instantly. By being smaller than the main valve — and opening at a slightly lower temperature (185-190 deg F) than the main valve (192-195 deg F) — the sub-valve irons out any spikes in the temperature of the coolant in the engine that may occur before the main valve can react. Basically, the sub-valve allows an additional degree of temperature control as the engine warms up.
Not all aftermarket t-stats have a sub-valve. This is not the end of the world, but it's a good idea to use one thusly equipped if the OEM unit sports one. The Miata's OEM t-stat uses a sub-valve.
Also notice the pee hole. This is simply a bypass hole that allows coolant to pee out of the engine when the t-stat is closed. Without this hole, coolant flow to the t-stat is stagnated during warm-up, which isolates the t-stat from the hottest coolant in the engine. The little flow through the pee hole ensures that the t-stat is seeing a continuous supply of hot coolant, and this is goodness. A secondary benefit to the hole is that it introduces hot coolant to both sides of the t-stat, warming it up a bit more evenly.
The pee hole also allows air to be more easily purged from the cooling system when you refill it with coolant. This works best when the hole is the high point of the t-stat since the liquid will push the air upwards as you fill — orient the pee hole at "12 o'clock" (left) when you plop the t-stat into the engine to ensure that no big air bubbles are trapped in the engine.
Finally, don't go installing a low-temp t-stat thinking it will give any performance benefit. It won't. Nor will it solve an overheating problem. All a low-temp t-stat will do is prolong the engine's warm-up period, so you'll use more gas as the engine will be operating in 'cold start enrichment' mode (i.e., running rich) for a longer period of time.
And if the engine is experiencing an overheating issue, a low-temp t-stat will only delay the inevitable.
In a desperate act of revenge, the oft-shunted concrete pillar in our parking garage sprang out and gave Project Miata a wallop.
Okay, that might be a lie. But we're keeping our eye on that sucker just in case.
Here's how it actually went down. One of our editors was stopped at a red light on a freeway off-ramp in Project Miata when the driver of a Chevy Blazer took it upon himself to rapidly shorten our car by a couple of inches.
We're in the process of going through the insurance paperwork, so stay tuned.