spec.this.miata

Derek and I pulled the head off the car last week. Among the list of to-dos while the head is off is to service the fuel injectors. Like most cars, the Miata has sealed injectors, but there’s still a bit an average person can do to keep them in top shape.

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.

Our Miata came with power windows, which are nice.  However, not having glass inside the doors is better than having it — not only for a weight savings, but for safety reasons too.  Because we have an open trailer, and the Miata sometimes stays outside overnight, it needs windows.  So what it needs are windows that can be taken out easily!

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.

I drove the Miata down to Laguna Seca raceway yesterday, following pop and Arti in the wagon.  The Golden Gate Chapter of the BMWCCA was holding a Driver Education event there, which I thought was a good choice for the Miata’s first outing since they hold the safest and sanest events I’ve attended.

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!

Here are some photos of the car after I got the dashboard back in.

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Below are some photos of the sweet exhaust that Tony fabbed up for the car. Now it is in “Laguna” (quieter) mode. There is a downturn that bolts to the flange in the rear that eliminates the rear muffler assembly.

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To-do’s before Monday’s event at Laguna Seca are to mount the rearview mirror, install the hood pins, and zip-tie the rollbar padding in.

I took some photos of the car this morning and posted them here:

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

Picked up the car from Tony this afternoon.

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!

Tony had pre-cut and pre-bent most of the tubing for the roll cage last Friday, so he was able to get most of the cage together yesterday. I went over this morning to figure out the best place for the seat, and I took some photos of the cage. He still needs to do the door bars (NASCAR-style, but still allowing the window to roll up and down). The tubing will be painted black when it’s all finished.  As always, Tony’s work is fantastic.  Look how close to the A-pillar the tubing sits.  Also, the bars that extend forward in the footwell are something you don’t see on every SM cage…

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!

Today I embarked on a string of small projects for the SM.

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.

I replaced the clutch master cylinder today.

It went smoothly until it came time to bleed the system. I had asked Arti earlier today if she could help me out, to which she agreed. However, when the master cylinder was installed and ready to be bled, Arti was sleeping. Just pumping on the pedal didn’t do anything, so I needed to figure out a way to simulate a partner pumping the pedal. The solution came in the form of a Shop-Vac hose extension — a rigid piece of 3″ diameter pipe. I would put it between the driver’s seat and clutch pedal to keep the pedal depressed. I attached a 2 foot length of vinyl tubing to the clutch slave bleeder valve, and sucked the fluid almost to the end of the tube. I put the tube into a bottle of old brake fluid, and proceeded to pump the pedal with the pipe, locking it into place with the driver’s seat. It was slow, but worked well!

One thing I’ve seen in other Spec Miatas is that they turned the tach so that the redline was when the needle was pointed straight up in the 12 o’clock position. With the instrument cluster out of the car, I thought I’d try my hand at making this change. After a few failed ideas, I finally figured out how to do this.

See this page for step-by-step instructions on how to rotate your tach.