The Targa Miata moves to the next stage

Surprisingly, the car runs much better with the crankshaft sensor plugged in. Write that down, folks.

More surprisingly, it didn't fix the dead tach. I spent some time chasing wires and it all looked good. I couldn't think of what I might have done to break it. So I went back to the FM instructions on how to wire a tach on an LS Miata. And we say to use a pull up resistor. Okay, that should still be in place. Right? 

But I couldn't find it. And I have a vague memory of finding a random resistor on the floor a while back, but I live the kind of life where random loose resistors are a thing. Did I just have it stuck into a connector and it fell out? Who knows. But what I do know is that when I sorta hotwired one into place, both the factory tach and my LED sequential one woke up.

Sheesh. Time to splice into the harness again. But then I started thinking about alternate solutions and I came up with this. A simple jumper with a 2.2k resistor inside between a couple of terminals on the back of the gauge cluster. I'm pretty happy with this setup, although it does guarantee that someday in the future I will change out this cluster and the tach will stop working and I won't know why :)

That looks like a tidy solution actually.  Bonus points for the printed heat shrink tubing!

DeadSkunk (Warren) said:

Keith Tanner said:

It seems like a reasonable test if you're trying to determine how furniture upholstery will age. Looks like I could pretty easily get the seats recovered in this without much concern. Won't tell us how the suede substitute deals with sweat, but at least it's pretty clear that it won't go threadbare. 

FWIW, I used to work in the automotive seating world, and ingress/egress testing was normally a minimum of 250,000 cycles.

250,000 cycles is the equivalent of getting in and out of your seat once per hour, around the clock, for 14 years. That's a seriously aggressive target! 

I think Mazda's target for their leather is more like 250 cycles. 

Spent some time just reassembling things after the hunt for the missing tachometer. I also installed this thing - a 3D printed cover for the fuel door release. Not really completely necessary, although mine has taken a number of hits over the years so it had to be straightened. This model needs some finessing and I'm not sure I would have paid what it cost me in raw materials (it's surprisingly big and took nearly two days on the bed), but it's not bad. Finishes things up well. Surprisingly light but of course it's basically hollow.

I also had to fix a problem with the hard top brackets on the back. This has been a long term problem, two nuts vanished on each side and the inner workings were floating around. The adjustment cover pivots from a hinge point at a front corner. It is locked in place with a little screw but those had seized on each side and had to be drilled out. So I was able to replace the missing nuts and give myself the ability to set the brackets up, but the covers were still free to rotate. Clamp-tite to the rescue!

I'll have my scales at home next week, it'll be interesting to see what the weight and balance looks like with that chunk of cage gone.

I lost a few of those nuts too, only to find that they were a standard metric thread but some crazy outside dimensions.  I remember much cursing at the bench grinder while I tried to grind standard nuts down to fit the brackets properly. I should have just bought the factory nuts I guess. 

8x1.25 with a 12mm head, no flange and a little thinner than usual. A little weird. I didn't have any so I flipped the bolt over so it was on the bottom.  It has the same size head. Then put more normal 13mm head nuts on top. Actually makes all the parts more secure as the bolt can't escape if it comes loose. 

A coworker took a cool shot of the car while it was out of the garage so we could do a video shoot.

That is all.

Keith Tanner said:

 

In fifty years, someone will find that and post it all over the Internet asking what the heck it is.

I happened to have the FM scales and hub stands in the back of my truck, so I took advantage of this fact to give the car a rough alignment and check the weight. 

The last time this car was aligned, it was a track car so it had a very low ride height. For street use, I've lifted it up quite a bit and thus lost a bunch of camber. Ride height is 12.5" front/13" rear, which is the ride height we use for FM springs as well. I'm running a lot more spring rate so I could run lower, but I'm okay with having some ground clearance. I set the car to have about 2.1* of negative camber up front and 1.5* in the rear, which should work pretty well. Slight toe in on the front and I have to admit I just jacked in a bunch of caster. I'll probably get the pros to give it a proper alignment later.

Weight came out at 2363 lbs with roughly a half tank of gas and the hardtop on. I always weigh with full fluids but I didn't plan ahead for this, so let's add about 30 lbs to that. At 2393, the car is right about 100 lbs heavier than the official curb weight of a 1995 Miata - but it does happen to have 4x the horsepower, so that's a fair trade. This car also has 5x as many brake caliper pistons as a stock Miata.

I kinda left this hanging.

I got distracted by building a big brake kit (more on that later, maybe) and a weird stock-looking race dash on this. I also had to solve a registration problem as I missed a renewal last year. Took care of the renewal problem by dumping a suitcase full of cash on the desk of the county clerk. And then there was nothing actually stopping me from actually driving it with the old-school gauges. So it's been going for drives.

Man, I've missed this car. It feels like its old rally self again, very eager to pile on the speed and surprisingly compliant given the spring rates. It loves to pull out of corners. Situation report:

- steering wheel was off by a spline
- brakes felt soft 
- passenger door speaker sounds like it has a bad connection or is blown
- the deep dish steering wheel was way too close to my chest with the new bolt-on (as opposed to welded) quick release
- related to the above, the combo switches are comically far from the wheel

Steering wheel alignment was an easy fix. I replaced the deep dish wheel with my Martini Racing MOMO. That also helped a bit with the combo switches and gave the car a different interior style. The deep dish suede MOD.07 was all business, the Martini is pretty. But I did install a carbon fiber horn button block off plate instead of a horn button, so there's that.

Brakes got a bleed. I'll get to the door speaker later.

But on the topic of brakes, my new brake kit design did not quite clear my existing wheel sets. So close.

Just for fun, I grabbed the clearance template for a wheel sold by my employer and checked. It seemed scarcely believable.

So I grabbed a wheel. Template is accurate.

And thus the Targa Miata got new wheels. I don't need them yet, but I will when I finish that brake kit. I've been pushing for them to be available in white, I think I'll have to paint these.

So, did your employer give you a discount?  

Seriously, looks good... those Kogekis have quite a bit more brake clearance than the 6ULs.  Are those 15x8 or 15x9?

I do get a little consideration, yes :)

15x9 with a 245/40-15. The 8s are similarly roomy. 

"Weight came out at 2363 lbs with roughly a half tank of gas and the hardtop on. I always weigh with full fluids but I didn't plan ahead for this, so let's add about 30 lbs to that. At 2393, the car is right about 100 lbs heavier than the official curb weight of a 1995 Miata - but it does happen to have 4x the horsepower, so that's a fair trade. This car also has 5x as many brake caliper pistons as a stock Miata."

I just wanted to highlight this bit. You guys race prepped a car, adding cage and all the safety gear, LS swapped it, and added 100 lb. Well, that is very, very impressive,  just sayin. We took the glass gearbox outta my awd Mazda rallycar and replaced it with a GT4 Toyota box and I bet we added 100 lbs right there, and  no where have I managed to remove weight elsewhere to make up for it. Very, very impressive and I wish I could do that!

I still have the old Wilwood big brake kit off this very Targa miata. It's getting ready to be installed on my turbo miata

Jay_W said:

"Weight came out at 2363 lbs with roughly a half tank of gas and the hardtop on. I always weigh with full fluids but I didn't plan ahead for this, so let's add about 30 lbs to that. At 2393, the car is right about 100 lbs heavier than the official curb weight of a 1995 Miata - but it does happen to have 4x the horsepower, so that's a fair trade. This car also has 5x as many brake caliper pistons as a stock Miata."

 

I just wanted to highlight this bit. You guys race prepped a car, adding cage and all the safety gear, LS swapped it, and added 100 lb. Well, that is very, very impressive,  just sayin. We took the glass gearbox outta my awd Mazda rallycar and replaced it with a GT4 Toyota box and I bet we added 100 lbs right there, and  no where have I managed to remove weight elsewhere to make up for it. Very, very impressive and I wish I could do that!

 

When I originally built the car - it was done on jackstands in my home garage, not at the shop - I built it as a four cylinder that had to hit a minimum weight with a full set of tools and spares (and a spare tire) on board. I think I was allowed to be 10% under the published curb weight. In order to hit that, I spent a lot of time looking for places to save weight without spending money. The wiring harness has been stripped down. The trunk lid is just a skin held on by pins, the dash is the same. The hardtop has a polycarbonate window.  The frame extensions that support the rear bumper and provide tie-down locations are gone. There's no HVAC. I did eventually pull out the manual windows and install power windows at the cost of 1 lb per door, but the switches are on the doors instead of the center tunnel to minimize the wiring run.

The V8 swap was done more with an eye to durability than weight control but all that previous work still remained. I even reworked the wiring to make the factory fusebox redundant.

It doesn't have the front half of the cage currently so it's not a fully prepped competition car anymore. Not a fair comparison to a proper rally car!

Now that is a cool idea for 3D printing uses! Did you find a CAD file for the caliper?

I was able to get one from my connections at Essex. There's a larger variant on GrabCAD but I needed a specific model. They're expensive calipers so it seemed a good way to do some basic fit tests without spending a boatload of money. I also have models for the upright and wheel and of course I was able to model rotors, so the prints are just a way to validate my models and prove how clumsy I still am at 3D design :D

The wheel clearance template for the 3D printed parts was cut on a laser cutter and the dashboard runs small embedded computers that communicate with the engine management via the in-car network and display results on addressable LEDs hidden behind gauge faces cut on the laser. Something weird happened in the last year, the 21st century arrived in my shop :)

Finally got a quote from Essex for the caliper I want to use. And it's almost 50% more than buying it through Demon Tweeks. So much for having an insider connection. I have to decide if I feel like sinking any money into that part of the project.

A friend painted his Kogeki wheels white and they look fantastic. I have been unable to convince my coworkers that this is something we need to offer to the public, so it looks like I'll be painting my own. Watch this space.

As noted in my analog race dash thread, the car is not good for night driving. My cool downfiring LED under the dash means the glossy white interior is lit up like a fishbowl. The headlights are pretty bad. The gauge lighting is all jacked up thanks to the new dash setup. So I have some remedial work to do there, as there is the potential for more night driving now than there was in the past.

There's a track day in a couple of weeks. I might bring the car out to see how it behaves in its new form. Should be a little less planted with the loss of the aero and the 200TW rubber, but that's part of the fun right?

Track day last weekend! I was also testing the race dash, I've done a race dash specific update. Heres's what the rest of the car was like.

How was the car? Slidey. Sooooo slidey. The track wasn't very grippy according to other drivers but the Maxxis VR-1 were struggling very badly. I used to track the car on 225 Toyo RRs. The 245 VR-1s lasted about a lap before overheating and then it became a matter of managing grip. Which was huge fun. A long sweeper where most cars can accelerate full throttle had me modulating the power to avoid 80 mph oversteer. Unless I didn't want to, in which case I'd just accelerate with some countersteer all the way through much to the enjoyment of myself and my passenger. 

Car was very loose but also very smooth and controllable. A big Bob Costascat, really. Of course, a lion is a big Bob Costascat until it accidentally removes your head while playing. Everyone who rode with me was amazed at how comfortable the car was while sliding around. Experienced drivers gave credit to the car, novices gave credit to the driver. We are experienced here so we know it was the car :) I think the tires helped there somewhat because they had a very gentle release and didn't snap at all. They just smeared across the surface. 

The suspension worked well, which is not surprising given that it's the same setup I've run for a while but at a higher ride height.

I took a session in a 95 hp 1.6 Miata with $4000 worth of suspension and 245 RRs and that was a great education in different lines for different grip/traction ratios. The V8 car needed lines that allowed it to accelerate as hard and as soon as possible, the momentum car was more interested in maintaining corner speed. Both quite entertaining and challenging in different ways. The 1.6 driver did note that the straights were much shorter in my car.

The coolant temp did get a little high, especially as the car heatsoaked between sessions. That was mostly because I was showing no mercy to the engine, I know that it doesn't like me flirting with the limiter all the time on this slow track. This is the nature of big power on a kart track at high altitude and on warm days. Short shifting helps avoid it and you don't really need to rev the nuts off this thing.

The transmission tunnel heat I was worried about? No problem. I could lay my hand on the tunnel after a session - it was warm for sure, but previously I was actually melting heatshielding. The DEI Floor and Tunnel material I put inside the tunnel was well worth the effort. Big thumbs up there.

I did end up putting down the second fastest time in the fastest class behind a turbo Exocet on Hoosiers, but that's more a matter of other competitors breaking their cars while testing and being unable to compete :)