With a race at Thunderhill in July approaching, Derek and I decided to do something about the heat. A typical summer afternoon in Willows can be 105 degrees or more, so of any race this season, that one was likely to be the hottest.

We looked at the existing cool shirt systems out there. All look very well made and definitely have the kinks worked out. However, there were two big issues with them from my perspective: they’re expensive, and they look like they’d be easy to make. Time for some D.I.Y.!

The overarching concept with the shirt is that cold water is circulated in a lot of tubes attached to the shirt. A small cooler serves to contain icewater. The water is forced out the cooler using a bilge pump, through tubing into the shirt where it pulls heat out of your torso, flows out of the shirt, and is dumped back into the cooler where it mixes again with the icewater. An important part of the system is a way to quickly connect and disconnect the shirt from the cooler — this is accomplished with dry-break fittings normally used in medical and industrial applications.

Parts

8+ Quart Cooler - Make sure the one you pick will fit where you want to mount it. Measure the available space, and get the biggest cooler that will fit. We got ours from Target for $10 or so. In hindsight, we TOTALLY should have gone with this one, since it looks to have a WAY better seal and the one we got leaks unless we cover the whole top in racer’s tape.

Pump - I got a 600 GPH Bilge Pump from West Marine for $25. The ones at OSH take AC power so those were out. The one I bought takes 12VDC power, so wiring it up to the car is easy.

To get the water in and out of the cooler, we used 1/2″ diameter, 3″ long nipples (pipe threaded on both ends). We may have been able to use 2″ long ones.

Fittings And Such - We found all of this in the plumbing aisle at the local hardware store (NOT HOME DEPOT).
- (1) 3/4″ female to 1/2″ female adapter
- (2) 1/2″ diameter, 3″ long nipples (pipe threaded on both ends). We may have gotten away with 2″ long ones.
- (4) Thin nuts, 1/2″ coarse thread. The nuts need to be able to thread onto the nipples.
- (16) washers that can slip over the nipples.
- (2) 1/2″ female to 1/4″ compression fittings with inserts to fit in 0.170″ ID tubing
- Roll of teflon tape

Tubing
- 50 feet of 1/4″ OD vinyl tubing. This is what goes in the shirt.
- 10 feet of 1/4″ OD polyethylene tubing. Typically used as the cold water supply for refrigerators. This is what goes from the cooler to the shirt. It needs to be different tubing because you use a compression fitting on the cooler end of the tubing.
- 5 feet of foam pipe insulation. 1/2″ inside diameter works fine.

Quick Disconnects
- (2) Sockets - McMaster-Carr part number 5923K31 - $8 each or so
- (2) Inserts - McMaster-Carr part number 5923K61 - $7 each or so
Optionally, get an extra insert so that you can connect it to the ouput line from the cooler and run the pump to drain the water from cooler without throwing away ice if you’re going to be running closely spaced track sessions.

Mounting - keeping the cooler in position
- (3) pieces of 90-degree aluminum, 1.5″ on a side, 6″ long
- (6) 1/4″ Bolts and nylock nuts
- Nylon strap with ratcheting tightening mechanism

Shirt - Get a TIGHT shirt. If you wear a Large, get a medium. It needs to be skin tight.

Fabric - An old cotton pillowcase is great source of the fabric. You sew the fabric onto the shirt to hold the tubing in place. Details to follow.

Silicone - A small tube of GE Silicone II works well.

Putting it Together

Cooler

Start by setting the pump in the cooler. Put the outlet against one of the sides of the cooler and mark its location. Find where the center of that circle is and drill a hole just big enough for the nipple to slip through. Drill another hole the same size toward the top of the cooler for the return line.

Spin one of the thin nuts onto one end of one of the nipples. Then, wrap that end with teflon tape and thread the 3/4″ to 1/2″ adapter onto it. Tighten. Slip one of the washers onto the assembly so it rests against the nut and goop up the washer on the side facing away from the adapter with silicone. Slip it through the lower hole in the cooler from the inside to the outside. Put the pump in the cooler, put teflon tape on the 3/4″ threads on the pump, and thread the nipple and adapter assembly onto the pump. Tighten. Goop up the hole on the outside of the cooler, and stack up enough washers on the nipple so that you can tighten one of the nuts onto the nipple’s threads all the way to the bottom of the threads. The goal is to maximize the threads exposed on the nipple after you tighten the nut.

Slip the other nipple through the top hole in the cooler and goop up around it inside and out with silicone. Don’t be shy. Use one or more washers on the inside and out. Stack up the washers just enough so that you can tighten the nuts on the inside and out all the way down — so the nut is threaded as far down as the threads on the nipples go. I used all 16 washers for this.

So at this point you should have both nipples mounted firmly in the cooler, with the pump attached to the lower nipple. We used some short sheetmetal screws to attach the pump to the cooler floor. We drilled holes first and squeezed silicone into the holes so that the water would not leak through.

Drill a small hole through the side of the cooler near the top for the pump’s wires to pass through. Goop up around the hole with silicone so this is not a source for leaks.

Put teflon tape around the exposed threads on the nipples on the outside of the cooler and thread on the 1/2″ to 1/4″ compression fittings. Tighten. Cut the polyethylene hose into equal lengths, slip in the compression insert to the tubing, and attach to the compression fittings. Wait to install the dry-break connectors until you get everything together and know exactly how long you want the polyethylene tubing to be.

Shirt

Hopefully you or someone you know has a sewing machine and is not afraid to use it! The concept here is that you will need to sew two panels onto the shirt — one on the front and one on the back. You will only use vertical stitching on the panel since the tubing is going to thread up and down between the panel and shirt. The tubing enters the front of the shirt one one side, goes up and down through the “channels” in the panel, hooks around to the back, does the serpentine thing again, and ends up next to the inlet tubing.

Here are diagrams of the front and back. The grey shaded area is the panel you cut out of pillowcase or sheet material. The red lines are the stitching, and the blue lines are the clear vinyl tubes.

Start out by putting on the shirt (TIGHT!) and your HANS and sit in a chair. Mark on the shirt (water soluble markers from my daughter’s art box worked great) where the HANS lays. Also mark 3″ or so above where lap belt falls - that’ll be the bottom of the panels.

Cut out the panels. Center them on the shirt horizontally, and line them up with the line you drew that’s 3″ above the lap belt. Sew up the sides of the panels, then sew the channels that will guide the tubing. The channels should be 1.5″ wide or so — but make sure there is an even number of them so the tubing works out. I used 12 channels on both the front and back.

Thread the vinyl tubing through the shirt, being careful to not twist it in the shirt — it’s not a huge deal, but it will not lay flat if there are twists. Leave 5 feet or so of extra tubing at the beginning so you can have flexibility in where things go at the end. The tubing should enter and leave the shirt on the same side, e.g. in the front on the left, and out the back on the left.

Finish Up

Cool! So now put the shirt on and get in the car. Play with different positions of the tubing to figure out what’s best for you. Don’t forget that the shirt tubing needs to get outside your firesuit somehow — I put mine through the lower zipper opening. Some people will cut slits in their pockets, which seems like an OK idea too.

Once you figure out where everything should go, trim the tubing and hook up the dry-break fittings. Also figure out where you want the cooler to mount in the car. Use the aluminum and nuts and bolts to locate it. Figure out how to mount the nylon ratcheting strap to keep everything tight. I used eyebolts that were already there for the passenger side lap belt.

The nice thing about this mounting setup is that to remove the cooler to dump it, all you have to do is loosen the nylon strap and pull the cooler out. No tools required.

Wire up the pump, ideally with a fused and switched circuit. You don’t want it on all the time, and if the pump burns up you don’t want to take down the car’s electronics. I made a power distribution block and fuse block that sits in the center console and used a metal toggle switch for the pump circuit.

Aftermath

I was excited to give the system a try at the Thunderhill race. The forecast was for 95 degree temperatures. In the first practice session, I hooked up the system and powered it on at the 3-minute board on grid. To my dismay, I didn’t feel or see any flow in the system. After all this work, I was really bummed out. I resolved to work out the system after this practice session. So I went out not expecting anything. Well in Turn 6 on the first lap, the cold goodness started flowing! OH IT WAS SO NICE!

I’d fill the cooler with ice, then pour in just enough water to run the system. This gives maximum cooling for the longest time, since the warmer water returning from the shirt will start melting the ice right away. If it’s too cold, run less ice and more water in the cooler, though I don’t see this as a possibility unless it’s really cold outside. After the session, I’d either remove the cooler from the car and dump it, or attach an extra insert to the line coming from the pump and run it to pump out most of the water, add more ice, then go out again.

It worked great through the whole weekend. Through the entire 30 minute races I felt sharp, and not once did I wish for the end of the race. Where I’m usually totally beat at the end of a session or race, I was not fatigued a bit.

I’m sure the $400 systems would work better to some degree, but for 1/4 the cost and a day or so of work, I’m satisfied.

I initially was looking for a local place near San Jose, CA that could flow test, refresh, and retest the injectors, but I didn’t find anyplace (I also didn’t look very hard). There are a few well known shops that you can mail the injectors to, they service them, then mail them back. We’re putting the head back on in six days, so there isn’t time for mail turnaround — and I’m too cheap to pay for FedEx.

I came across this article on Pelican Parts’ website that detailed a procedure for reconditioning the injectors on a Porsche 944. Fuel injectors are similar in function and operation across most cars, so I figured I could give it a go on the Miata injectors.

The procedure entails forcing carburetor cleaner through the injector using compressed air. It sounds kind of hairy, but in reality it was really straightforward.

The first thing I did was to remove the rubber seals from the injectors and give them a thorough external cleaning. After I did this they basically looked new.

I cut a 2 foot length of 8mm fuel hose and used a hose clamp to attach it to a valve attachment on my air compressor’s hose.

Take the other end of the fuel hose and spray carburetor cleaner into it until it’s more than halfway full. Use a hose clamp to connect it to the fuel injector supply side.

Since the injector will not flow without current applied, it’s necessary to involve some electricity here. I then took the injector wiring harness from the car and probed one injector connector to see where the wires came out on the other side. Each injector has two pins. The other side of the harness has eight pins, so it was a short exercise to see which of the 8 pins I should use. I hardwired one of the pins to one terminal of a 9 volt battery, and crimped a terminal onto the end of the other wire so I could touch it to the other battery terminal to “pulse” the injector.

Here’s the whole setup:

So the compressor feeds the fuel hose, which is filled with carb cleaner. I set the regulator on the compressor to 40psi or so. After filling the fuel hose with carb cleaner, I’ll open the valve from the compressor hose to pressurize the fuel hoze.  When the circuit connected to the battery is closed, the injector opens, spraying carb cleaner into the plastic tray.

I did each injector forward, backward (feeding the cleaner in through the ouput end — be gentle), then forward again. They all sprayed the same from the beginning, so I don’t think it will be a night-and day difference. But on the other hand I won’t be left wondering how it could have been.

I had heard of people who have made metal brackets that bolt to the window and hang them from the door sill.  Another person wrote in a forum that he put a bolt through the channel the window slides in.  This seemed like a good idea to me, so I went about trying to figure this out today.

Start by taking off the door panel (if it’s still on) and removing the 10mm and 14mm bolts that hold the various window parts on — the regulator, motor, two stops the white bumpers hit at the top of their travel, and the channel.  You’ll need to remove the door latch (3x phillips screws) to remove a clip that holds the raise/lower cable to the door skin.  There are a few 14mm nuts on the bottom of the door — remove them all.  Also remove the screws that hold the window to the regulator mechanism.  Toss out everything but the window and the shiny silver channel closest to the rearmost part of the door.

You should be able to remove the window now by pulling it up and out.

We’re going to focus now on the slider channel, which is the bright vertical piece in the photo below.

There is one 14mm nut holding it at the top and one at the bottom, on the underside of the door.  Once you remove those nuts, you should be able to easily take it out.

So here’s the big idea — we’re going to replace the copper colored bolt that is welded to the top of the channel piece with a bolt whose head sits inside the channel. These are the parts we’ll use — they’re all parts I removed from the Miata in making it “Spec”!  You’ll need to drill out the fancy washer so the bolt can go through it — I think it’s 5/16″.

It’ll be more clear later.  Start off by cutting the copper-colored bolt off the channel.  On one side, I just knocked it off with a hammer.  On the other side of the car, I had to use a hacksaw.

After cutting the bolt off, drill a pilot hole in the center of where the bolt used to be.  Well, it doesn’t have to be exact!  If you’re off, try to err on the side of drilling it too high.

Then drill it out to 5/16″ (or whatever the diameter of the bolt is.

Ain’t it purdy?

Take the channel out of the vice and flip it over.  Slip the fancy washer in the channel and center it over the hole.

Then slip the bolt through the hole.

Oops!  This one is too big.  No problem — just use some Channel Locks to persuade the channel to let the bolt through.

Voila!  This is how it should look at this point.

Now back to the window.  The red roller is what slides in the channel.  The big washer and bolt head will prevent it from slipping down in the channel now.  Using a torx wrench, loosen the bolt holding the red roller and adjust it as far to the bottom of the window as possible.  Mine didn’t move much.

Now put the channel piece back in the door — the bolt you used will line up perfectly with the hole in the door.  One 14mm nut at the top, one 14mm nut at the bottom.  Easy!  Now put the window in there, and it should stop nicely on the bolt head.

It’s almost like Mazda planned for this, since the window still seals up nicely when the door is shut.

Now taking out the windows is as easy as opening the door and yanking on it.  Putting it back in is just as simple — just line it up with the channel near the A-pillar, slide it down, and get the red roller in the channel down to your new stop.

After packing the tools and stuff in the wagon the night before, we headed south  for the track at 6am.  The drive down was OK — the car is not terribly uncomfortable even with the SM suspension (700 lb-in springs in the front, 350 in the rear).  The worst part was the exhaust that has a really loud resonance at around 3500 RPM, which is about 70 MPH in 5th gear.

We arrived shortly before 8am, registered, and stood around for the driver’s meeting.

Its first time out, the car was suprisingly good.  There were no funny handling traits, and the lack of ABS was a non-issue.  There were, however, some loud clunks and rattles coming from the rear of the car when we went over rough pavement.  I soon found out that the exhaust system had slipped out of its hangers, and was banging all around.  Upon fixing that, we found that the bolts holding the lower rear suspension brace were only finger-tight, so I took the opportunity to go over all the bolts in the rear suspension to be sure they were torqued down.  I also adjusted the rear brakes, since the e-brake handle seemed to need to come up higher than normal.

After safety wiring the exhaust in three places, the car was magnificent the rest of the day.

The car’s handling is simply fantastic … very controllable and balanced, no suprises, no hiccups.  It responds very nicely to throttle inputs, and just grips grips grips around turns.  It simply ran away from almost everything else out there in the handling sections of the track (turns 3/4 and 8/9/10). The lack of power was frustrating at times, but I know it will encourage me to squeeze every ounce from the car’s handling.

My lap times were pretty consistently around 2:00, which is 7 seconds slower than what I did in the M3, but I know that as I learn the car that difference will drop.  As a reference, a typical Spec Miata time in races at Laguna Seca is between 1:45 and 1:50.   Granted, those cars likely aren’t running motors with 135,000 miles on them, but I know I’m leaving a ton on the table in the handling and braking department.

I ended the day with a huge smile on my face, not only from the sweet experience of driving the Miata on track, but glad that I decided to do this project with Derek!

http://www.thenobot.org/pictures/20070112-miata/

He did the cage, fabricated an exhaust (with “Laguna” and “non-Laguna” configurations), mounted the seats, aligned, and corner weighted the car.

TC Design’s work is known for being the best around, and I think this car is a great example of that!

Alignment settings are:

• Front: -2.5 degrees camber, 1/16″ toe out
• Rear: -3.0 degrees camber, zero toe

This is a pretty aggressive alignment, but I trust that Tony knows how these cars like to be set up.  He mentioned that the rear is set low enough to occasionally bottom out in certain turns, but as long as I learn to manage the ensuing twitchiness in the rear end it will be faster than if it was set a bit higher.

The seat is very comfortable.  The head protection doesn’t obstruct my vision a bit.  It does take some work to get in and out of the car, but once the belts are latched it’s really great feeling.

I took these photos with my cameraphone.  The sun was setting, so the photos aren’t great.  I’ll take some more tomorrow with the real camera to get some better shots.

Here you can see how it sits:

Driver and passenger Recaro SPG XL seats.  Possibly a SM first?

View of the passenger seat:

Driver and passenger seats with the steering wheel in view.  The TCDesign quick release brings the wheel to a very comfortable position:

Needless to say, I can’t wait to get this thing out to Laguna on the 22nd!

The car will be done either tomorrow afternoon or the next day.  This includes painting the cage, fabricating the exhaust, alignment, corner weighting, and mounting the two seats.  I can’t wait!

First (and most exciting) was my “cheap-ass Intake” project. I had raided Home Depot on two occasions to stock up on tubes, adapters, and flanges so that I could build an air intake system for the car. I had ordered a K&N Filter with a 3″ inlet, and I knew that the Miata’s air meter inlet was a 2″ square. So my efforts were focused on this transition.

I spent most of my time in the plumbing aisle, where 2″ and 3″ ABS pipe was plentiful. However, once I got the 3″ pipe home, I realized that 3″ was the inside diameter, not the outside. The K&N filter would not slip over it. A 2 1/2″ pipe would have been perfect, but I couldn’t find any of that.

My wanderings brought me to the aisle with the gutter supplies. I was in search of the perfect flange, so that my creation could bolt up to the 4 studs that were at each corner of the 2″ inlet. I picked up what was to become the heart of the most beautiful and cheap Spec Miata intake system to date.

It was the flange that allows the downspout to connect to the gutter. Home Depot calls it an “Endpiece” (Item 049821150105, $4.31). It seemed that it just might work.

I got it all home, and decided to work out the “endpiece”. I cut the flange part out, leaving enough sheetmetal around it to still attach the screws. The opening in the flange was nearly a perfect match for the airflow meter inlet. So I drilled holes for the bolts, and voila — it went together almost perfectly. My filter with the 3″ opening was a little loose, so I wrapped several layers of duct tape around the metal flange to make it thicker. A K&N Filter with a 2 1/2″ opening would have been perfect.

So $32 for the filter, and $4 for the flange to connect it to the motor. I like it!

I also installed new Denso IK20 Iridium spark plugs, an accordion hose to connect the blower motor to the heater core (takes the place of the A/C condenser), and repainted the windshield wiper arms. Almost there…

Installed the “R” Chin Spoiler this morning. It ended up being fairly easy, there are just lots of clips and bolts that hold it to the existing bumper cover.