Project Miatabusa by dave coleman hayabusa miata gauges


Project Miatabusa is progressing on several fronts, with wiring, fuel delivery, induction, exhaust and subframe projects all happening in parallel. With three guys spread across so many projects, none of them are actually finished yet, but there's so much progress happening, it's time that we stop for a few updates. Over the next few days I'll be documenting the progress on each of these projects, one by one.

First up, the instrument cluster. Gauges might seem like a detail for later, but with massive wiring projects going on (more on those later this week), we have to know where the wires are going to go before anything can go back together.

There are two approaches we could take with this. Keep the original gauge cluster and try to feed it RPM and temperature data from the Hayabusa, or take the Hayabusa cluster and try to feed it speed and fuel gauge data from the car. 

All else being equal, keeping the Miata cluster might be easier. The temperature gauge problem could be solved simply by sticking the Miata temperature sensor into the cooling system somewhere (you'd want the stock sensor to stay in place so the ECU could still do cold enrichment), and watching the needle wrap past the end of the stock gauge would be endlessly entertaining. 

All is not equal, though. The Hayabusa cluster includes some diagnostic features we don't fully understand yet, and we don't want to fire up the first ever Miatabusa without all parts of the system in place. For the first car, at least, bringing the whole Hayabusa cluster into the Miata seemed like the way to go.

miatabusa instrument cluster before

The first idea was to remove the Miata cluster and just stuff the Hayabusa cluster in the hole. That's the kind of quick, simple shortcut I'd normally take if I were building a car by myself. But when Tim Taylor is up in his machine shop making fancy billet parts for one end of the car, I can't in good conscience be ghettofabbing the other end of the car. Tim has forced me to raise my game.

Eyeballing the two clusters, they're remarkably similar in size. If I could fit the Hayabusa cluster's guts into the Miata housing, the Miata housing would work as a perfect mounting bracket.

Making room for the Hayabusa cluster first meant taking out the Miata's gauges. Once you remove the instrument cluster, each of the gauges is held to the back with a couple of screws. Total destruction is only a few minutes away.

miatabusa instrument cluster before

The Miata gauge shroud easily snaps off the cluster housing, but it's an integral part of the assembly and can't be removed if we want to keep the gauges behind "glass" (plastic) like they are from the factory. Time for some Dremel action. The Dremel tool first has to be used to carefully separate the glass (plastic) from the shroud. These seem to have been heat fused together as they were quite stubborn about coming apart. The clear plastic is also terribly brittle and would be easy to shatter if you aren't careful with it.

miatabusa instrument cluster before

 A few tense minutes with the Dremel and the shroud is ready for anything.

miatabusa instrument cluster before

Now, the back of the cluster has to be cleared out of all the mounting bosses and warning light housings. I did most of this damage with the Dremel tool, but it turns out that if you remove all the light bulbs from the back of the housing, it can be clamped down to a mill and hogged out with real man tools. 

miatabusa instrument cluster before

The first test fit was promising. That eyeballing I did was remarkably accurate.


miatabusa instrument cluster before

Now would be a good time to mention that my car was broken into, right out in front of Miatabusa world headquarters, and my camera and computer were involuntarily donated to the local pharmaceutical distributor. This installment was shot almost entirely with my cell phone, which happens to be very bad at macro focusing. 

Enough excuses. The black line on the fuzzy circuit board below is where the edge of the Miata housing interferes with the board. Checking both sides of the board, it turns out I could cut this off without altering any circuits.

miatabusa instrument cluster before

 So I did...

miatabusa instrument cluster before

And there it is, a perfect fit!

miatabusa instrument cluster before

There are still details to work out. The white junk in the background needs to be black. The circuit board actually has to be attached somehow (it's just floating in there right now), and two of the gauges need to be figured out.

The gas gauge has to be calibrated, but that shouldn't be that hard. Both the Hayabusa and the Miata have a float moving a rheostat in the gas tank, so both are just moving in response to resistance. All we have to do is measure the range of each fuel sending unit and then make a simple circuit to make the Miata's signal look like the Hayabusa's signal.

The speedometer is vastly more complicated. The Hayabusa speedo gets its signal from a Hall effect sensor on the output shaft, while the Miata gets its signal from... a cable. The plan is to get the Hayabusa's Hall effect sensor to look at something on the Miata's output shaft or driveshaft, then adjust the signal with one of the many speedo calibration tools available for the Hayabusa. Changing final drive sprockets is common practice in the bike world, so tools for adjusting speedo readings are cheap and easy.

More on this project when we have it all figured out.



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Thursday, September 16, 2010 9:30 PM
Speedo solution get ABS sensors and ABS hubs for the front which are Hall Effect sensors which would also make for minimal custom fabrication.
Dave Coleman
Dave Colemanlink
Friday, September 17, 2010 3:50 AM
That's a really good idea. We might just try that...
Friday, September 17, 2010 6:32 AM
Doesn't a newer Miata use a sensor? Couldn't you calibrate the 'Busa speedo to read a Miata sensor (provided there is one in like an NB or NC)?
Friday, September 17, 2010 6:34 AM
newer NA's have an ABS system that you could just rig up to work like a speedo dont they?
Friday, September 17, 2010 7:22 AM
I really like the exposed chip board! Very nice adaptation. And the 13k tachometer just asks you to send the needle to the red!!! :D
Friday, September 17, 2010 8:05 AM
Lovin' the classic Spinal Tap reference Dave! Great to see the progress you guys are making. Do we get to see the intake manifold work next?
Dusty Duster
Dusty Dusterlink
Friday, September 17, 2010 8:11 AM
They broke into the car in front of MBWHQ (Miatabusa World Headquarters)?! The nerve of some people!

Dakota Digital and several other companies make fuel gauges that are adjustable. If worse comes to worse, you could simply install another fuel level gauge either in front of the current one, in place of it, or elsewhere in the vehicle.
Friday, September 17, 2010 9:22 AM
Mike already did the research the 93 miata was the first to be equipped with ABS (thank you Wikipedia...) get to the junkyard find some front hubs or buy new for around 100 but the sensors are like 260 new so get those from the junk yard and test them with a multimeter to see if they have voltage when the hub is at rpm checking it to factor specs of course.
Friday, September 17, 2010 12:24 PM
put some led lights on it and a case fan and your dash would look like an auto enthusiasts gaming computer.

On another note. For some reason looking at your dash made me think what it will sound like when you fire this car for the first time.
Saturday, September 18, 2010 6:38 AM
Dave Coleman
Dave Colemanlink
Saturday, September 18, 2010 4:32 PM
Aaron, I think about that sound every day!
Wednesday, July 13, 2011 3:57 PM
Hey gang,
Where do we stand with this project?
Dutifully checking every week but nothing for months, is it dead?
Dave Coleman
Dave Colemanlink
Wednesday, July 13, 2011 4:36 PM
Not dead at all! The machine shop we're working in just got really busy with paying jobs, so we're at the back of the line.
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