I’ve tried the dash back in the car and have come to a 2 conclusions. The first one is, if you are going to try a Miata dash swap in your car, don’t use a first generation dash (the NA), use a 2nd generation dash (the NB). The reason for this is the 2nd conclusion. When Mazda redesigned the dash for the NB cars, they must have had the Fiero in mind because it just fits so much better in every area! I was a little worried that after all the work getting the first dash to fit, the second one may have had changes that would make it much harder, or not possible at all, to fit in the Fiero. Well, the opposite is the case. The newer dash is a lot easier to fit than the first one. And since it looks so much better as well, it’s a double bonus.

Here are some of the areas that I’ve had to rework on this dash to get it to sit farther forward in the car.

Just above the steering wheel area there is a moulded part of the plastic that has to be cut out. It is the part running below the slot in the dash. You can see the part of the steering column mount in the Fiero that it will interfere with if you look in the slot. Not a big deal to just trim this part of the plastic out.



The only other area of the plastic dash that needs trimming is at the left where it contacts the Fiero steering column mount structure, where part of the flange in the car was trimming away for the fitting of the first dash. A few trial fits with marking and trimming and the plastic dash fits much better. The trimming of the dash here isn’t critical at all since it will be covered with a filler piece that will bridge the gap between the dash and the A-pillar extension in the car. At least, I think it will.



With the metal structure back in the dash, I could see where it needed trimming to clear the metal parts in the Fiero. The first area is the steering column support structure. I of course tried to minimize the metal to be trimmed out of the dash, but giving it some more thought, I’m not sure why. I’ve said before that there is so much metal in the dash and it isn’t really needed for this application, so why am I trying to keep it in? I guess it’s the engineer in me, if in doubt, stronger is better. Anyways, I marked where the interference was to cut this area out.



Then cut it out.



To keep a long story short, after several test fits in the car, I just hacked out both of the flat reinforcing pieces (instead of trying to nibble them out a little at a time) as well as the plate that is at the bottom of the pictures (the main steering column mount in the Miata I assume).



The 2 pads that are left, marked in white, are coming out next. After cutting this stuff out I realized that this area of the dash was redesigned compared with the early dash, and that makes it easier to fit in the Fiero. With the previous dash, the 2 curved pieces were the only thing holding the lower part of the steering column area in place, so they had to be trimmed out of the way, but not taken out completely since they were needed for support. With this dash they are actually curved the other way around and don’t interfere at all with the Fiero structure, so they can be left in place, while the 2 flat pieces are completely removed. Is that all as clear as mud? The bottom line is that the structure in this area of the Miata dash makes it easier to fit into the Fiero.

A couple more brackets in the passenger side that are trimmed off (I think these were holding the airbag). I think I only ended up trimming of the one on the left side of the dash since it was interfering with the Fiero defroster box.



The last thing that needed trimming off was the pipe at the left side of the dash. This is the same area that was trimmed in the previous dash to clear the flange of the column support structure in the car. But here again the redesign of the NB dash in this area makes it easier to trim. The pipe is actually curved here and doesn’t interfere as much with the structure in the car. You can see that a lot of it is still left, to give good support to that side of the dash. It is easier to do the trimming with the pipe structure removed from the dash.



Another test fitting. The dash has moved forward a couple inches now and is looking even better.



Oh, you can see in that picture the small piece of plastic that was trimmed out from just above the steering column area. You can also see how the metal structure in the dash sort of curves around the steering column structure in the Fiero; almost as if it were designed for this swap! I did end up trimming a little bit of this piece out to get a little more clearance; you can see it marked in white in the picture. That’s basically what the procedure is. Fit the dash in, mark the areas that keep it from moving forward, take it out and trim those areas off, and then trial fit it again. Repeat a few dozen times. Take a lot of pictures to help others that may also be insane enough to try something like this.

Rick

A couple pictures showing the area of the dash at the left, where the pipe structure is trimmed away to clear the flange of the steering column support in the Fiero. You can see the flange partially trimmed away. Actually it is trimmed away a little more than it needs to be since the trimming was done for the first generation dash.





Another area where the NB dash was redesigned compared with the NA dash is the centre console area, where it interfaces with the centre console structure of the Fiero. Remember the cutting that was done on the other dash in this area? A lot of structure was cut out of this area to allow it to fit down around the Fiero centre. Well, with this new 2nd generation Fiero-friendly redesign of the Miata dash, no trimming at all is required here! In fact, it gets even better since you can use a support piece from the Fiero and bolt it right in to the Miata dash structure.

There is a bracket that came out of the Fiero when the plastic centre console skeleton was removed. Since I tend to label things so I know where they came from, I labelled this piece as “under skeleton @ front”. You can see in this picture how the side metal pieces from the Miata dash fit around the centre console structure of the Fiero.



You can also see the piece I took out of the Fiero that is now back in place lined up with the threaded bolt holes in the centre console structure. Just a light tap on the ends of this piece with a hammer and it fits right in between the metal sides of the Miata dash. See how it lines up with the metal parts of the Miata dash, which gave me two choices on how to attach it. One option was to leave it where it was, lined up with the threaded holes on the Fiero console, and attach it to the Miata dash where it contacts that. It doesn’t overlap very much; there might be enough room to drill a hole in the Miata part and bolt the 2 pieces together, or there is certainly enough material overlap to weld it.

One of my goals in doing this dash swap was to try and do it without any really fancy tools needed, and without any welding. I have nothing against welding (it has become one of my favourite tools since I started the engine swap), but I was thinking of others that might want to try this dash swap that do not have welding equipment. So if I do choose to do welding, I will try and suggest an alternate approach as well that does not require welding (if I can). Sound fair?

Here is how I chose to do this. If you look at the picture again, you will see a threaded stud sticking inwards from the Miata piece, just forward of the skeleton bracket. So, if I slide the bracket forward, the threaded studs line up with the holes (actually slots) in the skeleton bracket. So there is virtually no fabrication, it uses existing holes and studs, and it positions the centre console of the Miata at the proper height on the Fiero. Can it get any easier than this?! OK, there is actually a little work to be done to attach this bracket to the dash and the car. You can see the stud a little clearer in this picture with the dash out and back on the bench.



The only problem is that the dash sides here are joined with a fairly hefty metal bar. That’s good in that it makes things nice and solid, but you also can’t spread the 2 sides apart to get the skeleton bracket in there. So the skeleton bracket had to be modified slightly to allow one side to slip over the stud:



Note that this only has to be done on one side of the bracket; you slip the first (unmodified side) over the stud on one side of the dash, and then use the new slot to get the other side in. Hard to believe these are pieces from 2 different cars; they fit so well together.



I wasn’t sure what angle this bracket should be at (it can rotate around the studs), so I left it loose until I sorted out how I was going to attach the main part of the dash into the car.

Rick

Looking great! I can't wait to see it finished. It gets tiring to keep installing and removing the dash, as I know when doing the Camaro dash swap, but in the end it is worth it to get a more modern looking dash.
Jim

I like it, but im doing a dash swap out of a 1998 Grand AM.

quote Originally posted by bowrapennocks: Looking great! I can't wait to see it finished. It gets tiring to keep installing and removing the dash, as I know when doing the Camaro dash swap, but in the end it is worth it to get a more modern looking dash. Jim

My basement is a flight of stairs down from the garage. That really isn't a complaint, since it is nice to have garage/basement access without going outside. With the first dash, for trial fitting, I did a lot of cutting and modifying of it right on the garage floor. With this one I take it into the basement to put it on the bench and do things properly. Certainly don't need a stair-climber for exercise when doing a project like this!

quote Originally posted by Fiero Reagan: I like it, but im doing a dash swap out of a 1998 Grand AM.

Hey, not a problem. We don't want to all be driving around in cars that look exactly the same! You may pick up a thing or 2 from this that may help you along, just like I have from reading about other dash swaps.

Rick

I am loving this! Keep those pics comin!

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1987 SE 2m4 Iron Duke Notchback... It's the only way to fly!

Great write up! Thank you for posting so many pictures. I know what dash swap I'm doing. Do you plan on using the miata guages or fiero ones or aftermarkets?

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1988 Metallic Red Pontiac Fiero CJB T-Top Coupe, # 784 of 1252

quote Originally posted by Fiero1K: Great write up! Thank you for posting so many pictures. I know what dash swap I'm doing. Do you plan on using the miata guages or fiero ones or aftermarkets?

Good question about the gauges. My original intention was to use the Miata gauge cluster as-is; this was before I did any research into how they all work. After looking into it in a bit of detail I don’t think this is workable. The Miata, like most new cars, runs the instruments off a “computer”, not directly off the individual engine/car sensors. I have the factory wiring diagrams for both the Fiero and the Miata and have spent a bit of time studying them.

Speedometer – The Fiero, like most cars with electronic units, use a standard signal of 4000 pulses per mile. I don’t know what the Miata uses (the wiring diagrams are not nearly as descriptive as the Fiero ones) but I’m pretty sure it doesn’t go along with the standard. So there would be a lot of trial and error in trying to get it to work with the Fiero wiring and in the end it might or might not work.

Tach – Again, this seems to be running off the computer so exactly what signal it is getting I’m not sure. I think the Miata uses a “wasted spark” ignition system, so it just might work with my V8 swap, but again I’m not sure.

Fuel gauge – The Fiero uses a fuel tank sender that goes from 0-90 ohms (empty to full). The Miata uses one that goes from 114-5. Would it work if I swapped the wires around on the gauge and added an appropriate resistor to it? I don’t know.

At this stage I’m pretty much ruling out using the Miata gauges. It might be possible to get them all working, but it would take a lot of research and playing around with them to find out; someone with a better knowledge than me of modern auto electronics might be able to do it. For me, it isn’t worth the time and effort. So my next step is to take the instrument cluster apart, take the one from the Fiero apart, and see if the Fiero gauges can be swapped into the Miata cluster. I’m not sure I would like the look of that, but it will be fun to take them all apart anyways. Failing this (and I really don't think the Fiero gauges in the Miata cluster is going to do it for me) I’ll get aftermarket gauges and build them into the Miata cluster. I think I’ve seen this done once or twice on Miata’s and it should look good.

So that is the short answer to your question.

Glad you are enjoying the swap. I know I am.

Rick

Not sure on the exact size of the Miata pod but you might be able to get away with using a pod from a car like a 95 Sunfire or one of the Grans Am or GP ones from that era.
I was able to get the Sunfire pod to fit quite nicely in my Nissan 240 SX dash. Dan

GM switched to using a computer bus driven gauge set in about 97 or 98 so. Camaro/Firebird gauges are completely compatable analog gauges up to 96 or 97. Somewhere around 96/97 they changed the fuel gauge. You might want to look at 8?-92 Camaro/Firebird because as I recall they have individual gauges not like the 93--on which are all on one backing plate. This is where pull a part comes inn handy as they are cheap. Alldata data base which is available at my local (King County WA) library has access to all the car wiring diagrams.
Jim

Leaving the instrument issue for now:

I put the dash back in the car (working with the padded piece of the dash left out so it doesn’t get scratched or messed up). It sits nicely on the center console now with the new bracket in place. I pushed the front/top of the dash right up to the windshield area of the Fiero. This of course only contacts in the middle and then forms more of a gap as you move to the sides (since the curve of the cut-down dash doesn’t match the curve of the windshield). There is sort of a metal platform at the windshield, extending back for maybe 1 ½” or so; I pushed the dash right up against this portion. A bit hard to see what is going on, but this picture shows the dash pushed up against the metal part of the Fiero. The padded piece of the dash, when screwed back on, sits a little behind this area. So hopefully the filler piece that I make can sit on the plastic part of the dash, just in front of the padded part, and butt up against the windshield.



So this more or less positions the dash in the car. The only problem is that the console area is pretty far back and fairly close to the shifter. It looked like a lot of extra work to keep cutting the dash to try and move it forward any more, so I’m leaving it where it is and I’ll worry about the shifter position later. I may just have to angle the shifter back a little to get more clearance with the centre console when the shifter is in “park”; not sure how this is done with an automatic shifter, but I’ll figure something out.

So back to the center console mounting. By pushing the dash forward in this area, I can mark the new holes that will line up with the holes in the skeleton bracket that was already attached to the Miata dash. You can see I’m pushing it back (well, actually forwards), while the skeleton bracket is resting on the Fiero centre console. So it is just a matter of marking new holes to drill in the console. I’ve marked the location with the soapstone which leaves a nice white area to drill.



I decided to drill and tap the holes. I’m not sure if this is a good idea or not. The metal around the existing holes is thick enough to take a good thread. Where I have drilled it is pretty thin, but it did take a thread. I do seem to have a tendency to over-tighten things and I might end up stripping the threads. If so I’ll come up with a better scheme later. You can see here that it worked out that the new holes are 1” in front of the old holes.



I spent a bit of time (way too much actually) trying to figure out what the thread was of the existing holes, and trying to see if I had a tap to match it. Then I got smart (or at least less dumb) and realized that I could put whatever thread I wanted so I used ¼ -20 thread/bolts.



Working on mounting the dash at the upper front sides now.

[This message has been edited by couldahadaV8 (edited 06-05-2010).]

With the dash being held in place by the centre console mounting, it’s time to secure it at the top.

The Fiero uses 2 attachment points at each side of the dash at the upper part (you already know this since you took it out!). There seemed to be pretty good access to the outer 2 mounting points just under the windshield. I made up some brackets from a small piece of angle iron with the ends bent to match the mating part in the car. The other end of the brackets just comes in contact with the end plates of the Miata dash structure.







With it held in place, I tack-welded the brackets to the Miata dash metal. This could have been done without welding by getting a little fancier with the brackets and bolting them onto the Miata part. Or use existing angle brackets re-bent to match the mating points at both ends. I didn’t use the inner mounting points that the Fiero uses in addition to these outer ones. They are much more difficult to access, and I was also afraid of getting in the way of the ducting that will eventually be running through this area. I took the dash out, took the metal structure out of it, and welded the brackets in place.

At the same time I did end up welding the center console bracket in because I didn’t know what size nuts went with the studs (and I was too lazy to find out). If you do not have a welder, just find the size nuts that go onto the studs and use them.



So, one more trial fit with all the mounting brackets made up.



You are going to curse me when it comes to putting in the bolts that hold the centre console part. You can see them well enough from the front, but trying to get your hand in is a bit tricky. Have some spares on hand for when you drop them down between the console and the plastic piece under the carpet; fish them out when the dash is back out. Note the "fishing" tool on the passenger seat.

The dash seems pretty solidly mounted. I’m not sure why the Fiero uses 2 extra mounting points at the top. Is it because the dash is mostly softer plastic and needs the extra support? Or am I missing something. It does concern me a little that it is quite a big, heavy dash and I’ve only got 2 small screws holding it in at the top. But it does seem to be solid in those areas so I’ll leave it for now. I’m not sure that I could get at the other 2 mounting points if I wanted to use them.

(Those clever individuals that studied the picture will notice that I’ve started playing around with making the filler piece to bridge the gap between the dash and the windshield.)

The only place it is flimsy is at the right side, down beside the glove compartment (which by the way fits and works fine, clearing the heater assembly). The metal structure of the dash is quite solid, just the plastic covering could use some additional support. I had a quick look at that area and once again luck was with me. There is a bracket that is maybe supposed to have a light or something in it?



It is fairly sturdy, so I’ll use a couple of modified angle brackets to attach the metal plate at the end of the dash to this bracket. It should end up hidden with a piece I’ll put in to fill this gap.

The fun and games continue.

Rick

[This message has been edited by couldahadaV8 (edited 06-05-2010).]

So I have a dash that fits and has all the brackets to mount it in place now (and looks really good!). One of the major stumbling blocks of dash swaps is how to fill the gap between the dash and the windshield. I’ve come up with a number of ways to do this. The first is what I started with the old dash, making a fibreglass piece that is moulded right onto the dash and extends forward. That seemed like a reasonable way to go with the old dash, but I don’t like that idea with this one. Because of the separation line between the padded part and the main dash, I think I can come up with a better way to do it.

The gap is obviously fairly small in the middle of the dash and then gets bigger as it goes out to the ends. Also it has a gentle curve to it, sloping downwards towards the dash ends. I could make a separate fibreglass piece to fill the gap, but it would either have to be moulded in place (to match the curve exactly) or be thin/flexible enough to bend to the contour when installed. Trying to mould it in place sounds like a horribly messy way to go, so that method is out. I thought a thin piece of sheet metal (aluminum was suggested and used by another “dash swapper”) might be a good way to do it. It would be strong, flexible enough to form a curve, could be painted with a textured black paint or covered with vinyl, and would be easy to make.

Before I went out and bought a large piece of sheet metal, I thought it would be good to make a pattern piece from thin wood. Of course once I made the pattern piece, I decided that just using the wooden piece for the filler would be the best way to go. So, since I like working with wood, I’ll make it from wood. If you are more comfortable with metal or fibreglass then the same basic idea could be copied using the other materials.

The piece was cut from 1/8” thick hardboard. I cut the main piece which is 48” long and then cut the end pieces separate. The reason for this is simple; the piece of wood I had was 2’ x 4’. I also thought it would be easier to manoeuvre (needed spell check for that one!) the filler piece in and out of the car for all the test fittings if it did not quite go from end to end in the dash area. Once I had this main piece fitting reasonable well, I cut 2 smaller pieces to fill the gaps at the sides/top of the dash.
This shows the 3 pieces taped together.



It sits nicely on the front of the dash and only has to be pulled down slightly at the sides to match the contour of the dash. This picture shows it, through the dirty windshield, sitting in place. Note how it butts up against the padded piece of the dash.



I was thinking of just painting it with a textured black paint, but then thought covering it with black vinyl would be the way to go and would match the dash nicely. So I made the piece a bit of a loose fit, front to back, to allow for the thickness of the vinyl. I don’t think it is really super critical to get the fit dead-on since it is hard to see right into this area of the dash anyways.

For the side filler pieces (between the sides of the dash and the car) I glued together a couple pieces of MDF (medium density fibreboard) to get the thickness that I needed and contoured them to what I thought looked good. The back side of these pieces (that doesn’t show) is just cut away to clear the Fiero structure. I nailed and glued these 2 pieces to the main filler piece to come up with this:



For someone that is more comfortable working with foam/fibreglass, that would be a good way to do it too. Oh, note that there has to be a cut-out to clear the VIN plate that remains on the car. So with this piece dropped in place, this is what it looks like:





It will be rounded a little more, and eventually covered in vinyl. I think it is a fairly easy way to make the whole filler piece and it came out better than I originally thought it would. Once the dash is in for good, I’ll put this piece in and put a screw or 2 into the side pieces from inside the dash to hold it in place.

Since the main part of the filler piece is very flexible and I was worried about breaking it, I reinforced it with fibreglass cloth/resin both top and bottom. It is still flexible enough to easily contour to the dash.



Strange looking piece, but it does the job.

Rick

Looking great! I used some hidden bolts in my dash filler panel when I put in the Camaro dash. I drilled a hole on each end of the filler panel and countersunk a 10-32 flat head screw and epoxied it in place. Then a drilled holes in the dash under the bolts and just added nuts from below to hold the filler panel. Hidden mounting! On the left side I used a long bolt and an extension.

You might consider 93-96 Camaro gauges...similar shape



Jim
PS...Your Miata dash looks way better than my Camaro dash

[This message has been edited by bowrapennocks (edited 06-07-2010).]

Thank you for all the advice and the comments Jim.

The filler panel seems to pretty much match the contour of the dash now, with just the weight of it pulling it down slightly at the ends. I will look into putting some attachment features into it in case they are needed to help pull it down into position.

I've given a lot of thought and done some tinkering around with the various instrument clusters and I'm going to go with aftermarket gauges. The ones from Speedhut are really cool.

Rick

I was just talking to a local friend who is going to do the Camaro swap and I remembered that when the dash was mounted in the Camaro, the filler panel was held down with Velcro like tabs.

I bought some after market gauges from

http://www.egauges.com/

You might want to check them out.
Jim

I wonder what the back of the NC dash looks like compared to the NB.

quote Originally posted by Gokart Mozart: I wonder what the back of the NC dash looks like compared to the NB.

I haven't a clue. Personally, I don't like it quite as much so didn't look into it. The best way to try it would be like I did with the first one. Find one in really bad shape that you could get cheap just to see if it would work. Since my dash is already out, you could buy it and send it to me and I'll trial fit it for you. If I don't like it, I'll send it back.

The NC Miatas are completely different cars than the NA/NB ones. They are basically RX-8 frames, so things will be very different in the dash area. Different could mean an easier fit or a harder one. Won't know unless somebody tries it.

Rick

It is nice to have a dash that fits well and looks good. It would be even nicer if the heating/ventilating system worked, so I suppose that is what comes next. Once again I’ve given this a lot of thought as to how to get it all hooked up. There are many ways to do this and maybe the way I do it isn’t the way someone else would. I don’t even know if the way I end up doing it will be the easiest way or not, but I have a very vague plan as to how to go about it.

The Fiero has what I will call the heater box mounted in the car. Bolted to this is the defroster duct. The heater box has an outlet that interfaces with the dash when the dash is in place. The dash has the vent piping that takes the air from the heater box in the car, to the dash vents. There is also a separate passage, both in the heater box and in the dash, that feeds air to the side window defroster vents. This is a bit strange that it doesn’t come off the main defrost, but is a separate passage. The reason for this may be that the Fiero leaves the defroster duct in the car, and the dash has an opening that sits over this duct, so interfacing the side window defrosters directly to the main defrost might have been difficult. This separate passage flows air to the side window defrosters when the system is in “heat” or “defrost”.

The Miata is similar to this, but with a couple differences. The side window defroster vents tie in directly with the main defrost; they actually feed off the same duct piping. Also, the defroster ducting leads, in the dash, to a separate plenum that interfaces with its own plenum in the car, adjacent to the heater box. So when the Miata dash goes into the Miata, it interfaces with the heater box and the defroster box. The Fiero sort of does the same thing, except that the defroster interface is at the top of the dash, so there is no defroster piping running in the dash.

To complicate things a little more, just in case you were actually following all that, most cars (Miata included) have the heater box interfacing in the middle of the car/dash. The Fiero has the heater box offset to the passenger side of the car. Which reminds me of another reason the 2nd generation Miata dash is better suited to this application than the 1st generation. The main dash reinforcing pipe in the Miata runs close to the heater box outlet in the Fiero. The 1st generation dash actually ran right in front of the box which I thought was going to be a problem with hooking up the heating system. The 2nd generation dash moved it just enough (to make room for the airbag?) to make it much less of a problem.

My original plan was to make an interface to mate the Miata heater ducting (in the dash) to the stock Fiero heater box in the car which would join when the dash was put in place; sort of like either car does it. That would leave the defroster ducting to worry about. I could cut a slot in the dash (which I have to anyways) that would fit over the defrost vent in the car, just like the Fiero does it. The one problem with this is that the Miata dash sits about 1” above the Fiero defrost duct and I would have to make an interface to seal this gap. This is not a big deal except that it is very difficult to access this area with the dash in the car, to measure the exact gap. Also, the side window defrosters would have to be tied in somewhere.

I thought it would be nice to have everything in the dash itself. This way I could work on it on the bench where it is much easier than working on it in the car. Also, there would be only one interface point which will be the Fiero-to-Miata heater box. The way I’ll do this is to take the defrost duct out of the Fiero (it unbolts from the heater box) and mount it into the dash. This piece interfaces with the main heater box in the Fiero, so my interface point will be between the 2 parts that are bolted together now. What I’ll have to make is an adaptor to mate the Miata vent box, that mounts in the dash, to the Fiero defrost/heater box, that I will be mounting in the Miata dash. Some pictures should help to describe it better.

You can see the various ducts in the Miata dash. The defroster ducts, that I don’t need, have a branch that leads to the side window defrost vents (which I will try and use).



The larger ducts on top of those are for the fresh air vents on the dash itself; one at the outer end of each side of the dash, and 2 that are in the middle of the dash and feed directly off the central plenum. I need to keep those as well.

This is the heater box in the Fiero. The foam covered flange interfaces with the dash when it is in place. The larger opening is for the fresh air vents on the dash. The smaller opening on the left is for the side window defrosters.



The piece leading out behind and up is the defroster vent; it is one-piece with the heater box outlet and interfaces with the large slot in the top of the Fiero dash. This whole piece comes off the lower assembly; it is held by 3 screws at the top and one at the lower interface. When it comes out, here is what the interface looks like in the car; defrost on the left, side window defrosters in the middle (small opening), and fresh air to the dash vents at the right.



So here is the plan. Take the screws out, but leave the duct in place for now in the car. Attach the Miata plenum into the Miata dash and put the dash in place, just with the metal dash structure, not with the plastic dash itself. Then attach some brackets from the Miata dash structure to the Fiero heater/defroster box. When I take the Miata dash structure out of the car, the Fiero heater/defroster box comes out with it, in the correct position to go back in the car and line up with the lower unit that is left in the car. Then I will have the dash with both the Miata and Fiero heater plenums in it, so I can make an adaptor to tie the 2 air plenums together. Simple, eh?

Rick

Here are my thoughts on doing two custom dash installs (355 aftermarket fiberglass dash, 94 Camaro).

It is very important to balance airflow. The 355 dash had all the air coming out the center vent.

I would stick with the Fiero defroster vent and cut holes in the Miata dash to line up with it. Here is what I did on my Camaro dash install using an aluminum filler panel. Notice that I had to cut down the vent grill a little bit.



I cut down the ductwork from the Fiero and added a piece from the Camaro ducts. The left side joins to the dash ductowk with a foam gasket, as well as center vent and vent on right side:




I am looking forward to you completing the install. Very exciting.

BTW, what year Miatas use that series of dash?

Oops almost forgot this. If you are thinking of using a Fiero subwoofer, plan that in now. I decided to add one after I did the dash. I had to go back and modify the ductwork to make it all fit....it is very tight.
Jim

[This message has been edited by bowrapennocks (edited 06-10-2010).]

quote [B]Originally posted by bowrapennocks: BTW, what year Miatas use that series of dash?

He shows pictures and years of the different generation dashes on the first page.

quote Originally posted by DefEddie: He shows pictures and years of the different generation dashes on the first page.

Pictures, yes. Years, no. Pretty sure the NB's were 1999 - 2005.

On my Nissan 240SX dash swap I also used the Fiero defrost vent and cut into the dash to mount it but that was because the nissan one did not line up with the ducting well enough to function. Dan

The subwoofer housing is for sale at The Fiero Store for about $20. I followed the advice of Fierosound on PFF and used the Tang Band 5 1/4" subwoofer. Not as good as a big one (8 or 10"), but I did not want to take up space elsewhere on the car. It mounts to the right of the heater core and bolts to the bracket that blue dingy thingy plugs into.
Jim

Nice work, nice writeup... have no doubt you'll have a gem when you're done! Thanks!

This is the Miata dash, with the metal structure in it, and the Miata air plenum installed.



You can see the openings in the side where the large plastic ducts fit in to take air to the dash vents at the ends of the dash; well, you can see the one at the upper right. This plenum has a short section out the back that leads to the 2 “eyeball” vents in the center of the Miata dash; you can just see those sticking down in the picture. This plenum is held in place with one screw, visible in the picture, that goes into the plastic dash, not the metal structure. It actually doesn’t need much holding it in, since the eyeball vents hold it fairly well and the vent pipes leading out of the sides sort of tie it all together. The problem is that I want to put this in place without the plastic part of the dash in place, only the metal structure. So I’ve screwed it in place, then taped it to the metal structure, then I took the screw out so I could remove the metal structure with the air plenum attached to it. This is what it looks like when removed:



This is it from the eyeball vent side; looks like something from the movie Short Circuit. Now with this installed in the car:



Once the dash mounts are in place, the metal structure on its own can be installed without the plastic dash. This is good for positioning things that you can’t otherwise see when the whole dash is in place.

You can see in this picture how the Miata air plenum is in the centre of the dash, and must interface with the Fiero plenum which is offset to the right.



So now I want to attach the Fiero air plenum (heater box) to the Miata dash structure. There happens to be a very handy bracket on the right side of the plenum that I can use.



I bent an angle bracket, peeled off some of the foam from the air plenum, drilled a hole, and bolted it up. Worked out almost too easy on that side.



The left side was a little more difficult, but not too bad. I cut a piece of sheet metal, bent it, drilled a hole in the plenum, and drilled and tapped a hole in the dash pipe.



So now I can remove the dash from the car, and both air plenums come with it.



These air plenums are both in the correct position with respect to each other, both attached to the Miata dash, and the Fiero one mates with the air box in the car when the dash is put back in. The plan is to make a connecting duct to join the two (within the dash). This makes the dash unit self-contained. When it is installed back in the car there is nothing that needs to be hooked up separate as the Fiero duct will mate with its corresponding part in the car, and the dash will contain all of the ducting for the vents.

Rick

You are making this look WAAAYYYY too easy..

And, I hate you for adding another item to my "to do" list.

This is a fantastic idea, can't wait to see the end result..

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Currently in the middle of my 88 + 3800NA swap

Very well explained and illustrated. Props for you. It causes me to consider doing it for myself. Is the Fiero defroster vent in the dash going to exit within the filler piece that joins the Miata dash to the windshield?

Ken

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'88 Formula V6
'88 GT TPI V8

quote Originally posted by aaronkoch: You are making this look WAAAYYYY too easy.. And, I hate you for adding another item to my "to do" list.

I did want to show it in enough detail so that somebody else could duplicate it. A consequence of that approach is that it does looks like an easy step-by-step project. What I don't show (and can't) are the hours I spend thinking about how to do every step. I'll take measurements and make sketches, put the dash in, take the dash out, think it and rethink it. This actually cost nothing other than time, but if you can't be working on the car, then thinking about how to do things is the next best thing.

As for your "to do" list, well, mine is up to the car after the one that comes after this one (seen Factory Five's new revised GTM? -- wow).

Rick

I’ve been working on the duct to join the two air plenums in the dash. No, I didn’t use wood this time, I used sheet metal. I did consider using fibreglass over a foam core but thought the sheet metal would be quicker and neater. Again, if you are very comfortable with fibreglass, use it. I basically made all 4 sides, one at a time, and put them on temporarily with Clecos. If you are not familiar with Clecos, they are sort of a temporary spring-loaded rivet. They hold things together that will later be riveted. If you ever see a metal aircraft under construction, you will see Clecos sticking out all over the skin. What I made is basically a 4 sided box, with the sides on angles to match up with the 2 units.







I taped the edges of the box together temporarily and then removed it from the dash.



I riveted the sides of the box together and then riveted it to the Miata air plenum. I didn’t rivet it to the Fiero plenum yet; I’ll wait until the dash is ready for final assembly so I can make sure I haven’t missed anything. I didn’t use any sealer on the edges of the box, or where it joins onto the Miata plenum, but I will later.

This shows what the box looks like in the dash:



This is looking up, into the part of the Fiero duct that was removed from the car. The dash air will flow from the Fiero up into this duct, and the piece I just made directs it into the Miata plenum where it flows out the 4 dash vents (the centre 2 come directly out of the plenum you see here, and the outer 2 are connected by the stock Miata vent tubes you can see). Looks nice and neat.

Since all the riveting holes were drilled in all the parts while in place in the dash, I could take the Miata air plenum out and rivet the duct to it without the dash in the way.



On the insides where the rivet is up against the relatively soft plastic, I used washers with the rivets to spread the load.



Putting all the various parts back in the dash does require some thought. The metal framework screws into the main plastic dash piece. The black padded part screws on the front of the dash. The air plenum goes inside along with the Fiero plenum. The various air ducts plug in. Some screws are blocked by the parts that go over them, so things have to be done in the right order. There is a lot of hardware to fit in, and the dash does get surprisingly heavy as it adds up. It does all seem to be coming along nicely though.

Rick

Are you going to have the door panels curve into the dash?

quote Originally posted by Gokart Mozart: Are you going to have the door panels curve into the dash?

If you look at the picture of the NA dash on the first page you can see how it curves back at the ends to match the door panels. One thing I like about the NB dash is that it doesn't do this nearly as much. You can see from the pictures of my dash how it is basically flat at the ends. The door panels match the dash contour to some extent, but not as obvious as the NA parts. I have a set of door panels that came from the same car as the dash and I will be installing those onto the doors, but that will be another project after this part is completed. The stock Fiero door panels don't look too bad with this dash for now. The Miata door panels look to be a close fit to the Fiero doors. The interior handle/release will have to be relocated to use the Miata one. The door panels won't actually blend into the dash due to the dash being inset from the door panel a couple inches; that's where my filler piece on the sides of the dash comes in.

Rick

Still working on the heating/venting system in the dash. One minor thing I did was to take off a little bit of plastic from the ends of the mounting tabs that hold the defroster box in the Fiero (at the top). They stick up a little too high and can interfere with the filler piece sitting down properly. A quick touch on a disk sander takes care of them.



There is also a minor issue with the order of assembly of all the stuff that has to go back into the dash. The Miata heater plenum attaches to the plastic part of the dash with one screw. You can see the tab that takes the screw, and the plenum in position without the screw yet. The plenum has the sheet metal duct adaptor that I made riveted to it.





So the problem is this. If I put the screw in to hold the plenum in place, then rivet the Fiero defroster duct onto the adaptor duct I made, I can’t get at the screw to take it apart. If I rivet the whole assembly together before installing it (the Miata plenum, the adaptor duct, and the Fiero plenum) then I can’t get at the screw to install it. One of those really minor things that probably takes more time to think about and figure out than it should. I’ll just leave the screw out since once everything is together the Miata plenum can’t really go anywhere.

Remember that the Fiero uses a separate duct for the side window defroster vents? I’m not running them from that duct, so I covered it over.





I still needed to hook up those side window defroster vents. Things are getting pretty tight in that area of the dash, and I could probably do without them, but I decided to try and get them working. I’m not real happy about how it all came out, but I think it will work. How much air will actually flow through them I’m not sure, but something is better than nothing. Here is what I did.

First thing I did was to put the fresh air ducts back in the dash. I don’t know if I remembered about this duct when I made up the support bracket, or just got lucky, but it sure comes close to the duct.



The ducts are very soft/flexible material, so a little interference is OK. I had to cut the bolt down to give a little clearance with the duct. The other side is not a problem with the way it is tucked up. It is a problem trying to get it in and out (good thing it’s flexible).



This next picture shows the Miata and Fiero air plenums in place (without the adaptor duct I made) and the fresh air and side window defroster ducts from the Miata.



The side window defroster duct is sticking out too far and will interfere with the dash fitting into the car. But it is aimed at the defroster duct from the Fiero, so that will be a good thing to tap it into. So I figured that if I cut the side window defroster duct down, cut a hole in the side of the Fiero defroster plenum, I could run a tube between the two that will carry air to the side window defroster whenever the Fiero defrost is selected. One concern with this is that the Fiero defroster plenum is only about ¾” wide, so you can’t put a very large duct into the side of it. I suppose I could make something out of foam/fibreglass that adapts the shape of the defroster plenum side into a round pipe, but it seemed like more trouble than it was worth. And I was getting lazy at this stage with something that I didn’t think was too important. So I cut the Miata defroster pipe down, and joined it into a hole in the side of the Fiero defroster plenum with a length of plastic tubing (plumbing store stuff, about ¾” dia).



Yea, I know, it doesn’t look that great. I angled the end of the pipe that is in the Fiero plenum so it can sort of scoop the defroster air that is flowing up the plenum. I’ll seal up the end that goes into the Miata duct. This is what the pieces look like:



I found an adaptor that fits on the end of the pipe and makes a better fit in the Miata part; it still needs to be sealed, but this helps to hold it in place. The piping is very stiff and I needed it bent. I found that a heat gun works nicely to locally soften it; heat it, bend it to the right shape, let it cool, and it holds the new shape. This is the stuff I used:



The defroster vent piping on the other side of the dash:



The windshield defrost area still needs work. There is no hole/slot in the dash for the defrost air to come out, and the defroster plenum sits about 1” below the surface of the dash, so it needs something to join it up the dash.

Rick

I really like what you are doing! I just want to buy another Fiero to do a Miata dash install! Keep up the great work.
Jim

I put the Fiero defroster plenum back into the Miata dash and marked roughly where the opening has to be in the dash.



I was going to cut a slot for the defrost, but the opening comes so close to the front of the dash (remember that this is behind the filler piece that bridges the gap between the dash and the windshield) so I thought it might be better to cut an opening from the front of the dash. The filler piece will form the 4th side of the defrost opening.

I transferred the position of the defrost opening to the top of the dash and marked it. I kept it a little on the shallow side, figuring I could always make it bigger later if it doesn’t line up exactly with the plenum on the other side of the dash.



I then used a sharp knife to cut away the vinyl covering and the foam underneath.



Then used the air body saw to cut through the plastic dash. There are actually 2 layers to cut through. The upper dash piece with the black vinyl covering has a plastic backing, then the main part of the dash has to be cut away as well. It is a little unnerving making this cut since I kept thinking the whole dash could be ruined if I mess up this cut; go slowly and carefully.



The cut edge was a little rough and I tried smoothing it up by trimming it with a sharp knife. It was tough to get it looking really nice with this, so then I used a belt sander on it and that worked great to smooth it up.



There are a number of options at this stage. Since the edge of the opening came out much better than I thought it would, it didn’t need much more work. I still do need something to match it up with the defroster duct under the dash. I could have just made an extension piece and attached it to the defroster plenum and had it butt up under the dash, but I didn’t really want an unfinished slot in the dash. Painting the edges black might have been enough since it is hard to see that far forward on the dash. What I decided to do was to make a fibreglass piece that is a combination finished edge on top and then extends down to match up with the Fiero plenum. One of those things that I hadn’t fully figured out yet, but decided to start on anyways and work out the details as I go. Oh, if you should do this and decide to just paint the cut edge, be a little carefull of what kind of paint you use since solvents could attack the foam padding.

I masked off the top of the dash and laid some fibreglass mat on it so it would give me a piece with the same contour as the top of the dash.



One caution with doing this. I had seen people put masking tape on a dash, or other item, and then fibreglass over it. Maybe I didn’t use enough layers of tape, but the tape did get attacked by the solvents in the resin and dissolved a bit. The tape came off all right but it left a sticky residue on the dash. When I cleaned that off I could still see evidence of where the tape was. It is only noticeable in the right light, and even then you can barely see it, but it is something to keep in mind. I’ve decided to use aluminum foil where ever I can from now on.

When this piece was cured, I removed it and trimmed it down a little (still leaving it oversize for now). At the same time I made this piece I laid up some mat/resin on a flat sheet (covered with aluminum foil) to make myself some fibreglass sheets for the next steps. A piece of this cured sheet was cut to size and bonded to the upper piece to form the 1st side of the defrost duct adaptor.



When this was done, some small side panels were added.

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Seems to be working out OK. This will give me what will look like a defroster vent opening from the top of the dash, and it will match up with the Fiero defroster plenum and guide the air up to the dash opening.

One other small warning. I supported the dash on the bench by using a jack-stand under the middle of the dash (think it will support the weight OK?). What I didn't realize at the time was that this was causing the dash to bend just a little bit so the contour of the fibreglass piece I made doesn't quite match the contour of the unsupported dash. Not a huge difference, but it is there if you are being picky (which I suppose I am).

While I'm slowly finishing up this piece I'm starting to work on the Miata centre console installation. More fun to come.....

Rick

Great progress!

If I may make a suggestion about the center console: I drove my NB for years, and always HATED the center console, no cup holders, and the little door to the storage compartment seemed to catch on stuff and was generally annoying. The styling was good on it, but everything else made me angry.. See if you can work in a useful cup-holder while yer at it.

Another idea, use the airbag defeat key slot as your ignition, and put a start button next to it.

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Currently in the middle of my 88 + 3800NA swap

quote Originally posted by aaronkoch: If I may make a suggestion about the center console: I drove my NB for years, and always HATED the center console, no cup holders, and the little door to the storage compartment seemed to catch on stuff and was generally annoying. The styling was good on it, but everything else made me angry.. See if you can work in a useful cup-holder while yer at it.

That's strange. Take a look at the picture of the NB interior on page 1. That, other than the colour, is what I have and the 2 small doors are both cupholders, then it has the larger compartment behind those. What am I missing here?

quote Originally posted by aaronkoch: Another idea, use the airbag defeat key slot as your ignition, and put a start button next to it.

That's an interesting idea. I was actually thinking of taking that panel out and making a small storage compartment out of it. My thinking right now is to have a radio with an iPod adaptor, and use this small compartment to hold the iPod (or a Bluetooth cellphone that is linked to the radio). I'll start playing around with it while I'm doing the centre console, and generally figuring out what switches and instruments I need and what will go in the centre console pod.

Rick

Oh, they're cupholders, just miata sized ones. Try balancing a McD's large in there sometime..

They also won't hold:
Green Tea bottles (glass ones)
20oz Soda bottles
Anything larger than a dixie cup.

Also, try shifting when those doors are open/up, or ANYTHING is in them. It may not be that big of an issue in the fiero, as the shifter is higher, but in a miata, the cupholders were practically useless to me.

I can't wait to see what you come up with, as I may follow your lead once I get my swap running here in the next few months...

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Currently in the middle of my 88 + 3800NA swap