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We did not begin by deciding that we'd change every single major interior component, but that's how it turned out.

It began so innocently:

Z22.jpg

 

During initial strip down, both Sigfrid and I were stunned by the sheer weight and baffling complexity of many of the 280Z components. It was obvious that Datsun had just layered modifications onto the originally simple 240 platform, which lead to silliness like the 280 HVAC controls (comprised of cable, electrical AND vacuum actuation).

And it was all made of metal.

 

The above pic shows our solution, the entire HVAC system from a Miata.

It features simple/easy cable actuation and the electrical is practically freestanding from the Miata harness and thus, extremely easy to wire in (basically, it needs a fused/relayed/switched +12v and a ground). The blower motor housing was modified (using a Home Depot Racing ABS plumbing fitting) to pull fresh air from the passenger side fresh air duct and the original fresh air intake (wiper cavity bottom) was blanked off.

There are so many brackets and mount points on the firewall that install was super simple and all three parts (blower housing, (gutted) AC  box and main control/heater core housing) can be installed as if stock...no weirdness or zip ties.

Because the Miata parts are all plastic, we probably saved 15lbs or so.

 

Obviously, the chassis wiring is all custom as well but that's only pertinent to this interior discussion in the fact that all the wiring has been removed from the dash itself, permanently hung on the firewall with only pigtails for the switchgear extending out.

 

It was a short- and almost inevitable- step to swapping in the entire Miata dash.

Our original Z dash was cracked and capped, the gauges were tired looking and the plastic trim bits either missing or broken.

And it too was made of quality Japanese steel and was ungodly heavy.

 

After some initial trimmage and fitting the Miata dash looked quite promising, so we committed to the swap and carried on. 

And the dominoes started falling.

 

Here's where we are now.

int7.jpg

 

Jeez, where to start?

2002 Miata dash

Lexus ES300 column switchgear and trim

Miata gauge cluster

Audi S4 steering wheel

Honda START button

Ford change/cupholder (change drawer modified to hold iPhone which connects into headunit)

Maxima doorhandles with integrated locks

Dodge Caravan doorseals and Honda sill plates

Honda Del Sol ebrake handle trim and gaitor

Honda Prelude seats w/ Mazda single retractor belts (seats mounted with stock runners in stock mount points, belts also in stock mount points)

Subaru hood release bracket (our original was broken)

 

It all works.

 

Some of these changes lead to deeper rabbit holes than others- for instance, the column switches.

Turns out the ES300 wiper motor is a near drop-in replacement for the Datsun original and the wiper harness is basically standalone, so why not use the switches that came with?

The wiper motor uses a ball and socket linkage connector and our linkage was all sorts of loose and worn out, so lets replace that too! Then the pivots were crap, so two Mazda 6 driver side pivots were installed. The stock wiper arms no longer fit (and were aesthetically undesirable anyway), so two VW Jetta passenger side arms were obtained.

Then the linkage was custom fabbed.

We probably have 40-50 hours just in the wiper setup.

But we have great coverage with multipoint delay and two speeds with one touch wash/wipe.

 

The switches look nice and have a very satisfying tactile operation.

 

I had to make a custom slipring for the horn contact on the Audi wheel, it originally had an airbag and "clockspring" transfer device...that was simple but the TS cancel collar I've had to make is not. On version #3 now, I'll get it eventually.

 

We are only now getting to the final install of the interior, having just installed the sound mitigating package and the new carpet.

The doorpanels need to be redone to better match the new interior design (the plastic chrome and fake wood trim ain't cutting it) but we wanted the doorhandles done first, just in case. They turned out great (took a few days to get the new lock linkage working well) and we've eliminated that irritating push/pull knob on the door frame...the one that prevents hanging your arm out the window like any good cruiser do...).

We're just beginning to conceive the center console.

We have a RX7 shifter bezel and a Honda armrest we'd like to use, both are crudely cobbled to our broken stock console base in the pic and this is the biggest "work in progress" left.

 

She gets pressed into daily driver status by April 18th, so we're concentrating on the basics now and will resume the finish interior work as time allows.

 

All the parts required to get the gauge cluster working are ordered and a day's work should finish that off. The Miata fuel gauge will interface seamlessly with the FC gas tank sending unit and needs no rewiring (yes, I installed a mint condition S5 RX7 18 gallon tank with internal fuel pump). We're replacing the Miata water temp and oil pressure gauges with more accurate/responsive VDO units but will use the Miata gauge faces and needles for an OEM look. Both the tach and speedo will require Dakota Digital boxes (also ordered) and the speedo also needs a VSS signal sending unit to replace the stock mechanical drive. Not sure what's happening with that yet.

 

Not much of the original Datsun remains other than the body shell and the drivetrain.

It didn't consciously start that way but sure as shootin ended up like it.

 

 

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That is pretty cool.  How close in size is the Miata dash to the original?  Any more photos you could show (where the dash meets the windshield, where the dash meets the pillars/doors, shots from a little further back, etc.)?  I (as well as others I'm sure) am curious as to how it all looks when seen along with the rest of the car's older styling.  Very cool mod though.  I'm interested to see what your solution for the center console ends up being.

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That is pretty cool.  How close in size is the Miata dash to the original?  Any more photos you could show (where the dash meets the windshield, where the dash meets the pillars/doors, shots from a little further back, etc.)? 

Width is pretty close, the Miata dash being a bit narrower than stock but the Miata dash is deeper than original and must be trimmed all along the front edge. We removed most of the defrost vent area on ours and are still creeping up on final fitment. The dash was gutted of all metal support structure except for the center stack, all ductwork left intact...it's basically just a plastic shell and easily removed solo.

 

The biggest obstacle was the steering column location.

With the Miata dash centered on the trans tunnel and the dash duct manifold aligned with the HVAC center box, the Z steering column was about 1" off center (to the left) of the gauge cluster. Some judicious bending of the upper mounting bracket got us much closer but it's still maybe 1/8" shy of perfect. We may be able to get it by manipulating the center fit a little but if not, it's fine as is.

 

The Miata dash has a pronounced arc across the width that falls away from the flatter Z windshield bottom. It's fine in the center and drops about an inch at each corner. The stock Z apillar trim is smaller than the Miata dash is expecting. We've not figured that out yet but the effect is not glaringly obvious and can wait.

I have no pics specific to your request other than this shot from the hatch:

Z16.jpg

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That is sexy my friend. My dash is apart at the moment installing speedhut gauges. Taking me a year. Hahaha. Don't ask.

 

I always wondered what dash would fit in these s30s. Seeing yours makes me go that route.

 

I need to figure out which wire goes to the senders. Each time I search none of the wires match any diagrams

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The wiper motor and steering column switchgear is from a 1999 ES300.

The switches are made by Niles and used by other manufacturers, in fact, Mazda uses slightly less "deluxe" versions (they typically lack a fog light switch or have less fancy wiper delay options) that look identical. I actually had switches from a Protege but when I saw how perfect the Lexus wiper motor was, I decided the wiper circuit got simpler if I used the motor and switches from the same car.

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Defrost vents finally installed and believe it or not, it took almost eight hours.

Actually mounting the eyeball vents was fraught with danger, the dash vinyl skin is very thin and very brittle...even an exacto blade would chip, rather than slice through it. There are a few booboos but we're not done with the dash top yet and it should all come good later.

defrost1.jpg

 

defrost2.jpg

 

We bought a Miata center console on spec, didn't have any idea how it might fit but figured it was the logical starting point at least.

Much to our surprise, it almost dropped right into place. Shifter boot was perfect and despite the lack of a relief in the side, the ebrake handle clears.

We started jiggering with the position of the dash to close the gap between center stack bottom and the console and got it very close...as I said, we had no clue if it would even work and suddenly, we're almost done!

 

All this unforeseen goodness had a downside though... the ducting manifolds in the dash no longer matched up with the outlet manifold on the heater box.

So we had to reposition (like, 1/2") the heater box...which meant the AC box and ultimately, the blower motor had to move also.

THAT is what took so long.

All done now though and it's still a one man job to install the dash...takes about 15 minutes to do the whole hook up.

 

I tried getting pics through the windshield to show the vents and the dash/firewall gap but sunlight washed them out.

Basically, we can't trim the dash front any further than it now is, you can see the somewhat raggedy edge in the pics.

It fits the profile of the Z firewall very closely but leaves a crescent gap in the middle- maybe 15" long and 5/8" wide at the center.

We always knew we'd need to make a garnish plate to finish this intersection but needed the dash to be final installed before figuring that part out.

Well, we're there now.

 

A few more hours to finalize wiring and the whole dash will be complete...I'm very excited.

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It's from a NB, so 2000-2005(?).

 

We never planned on using the stock dash- once it was out it never went back in and I never really looked at it to see how it might mate with the Miata parts.

Given how easily the Miata HVAC went in to the Z (bear in mind that "easily" is a relative term), I'd guess it could be integrated with the Z dash. If you did so, you'd certainly want the Miata control panel (w/ cables) to operate it as it's a completely different approach than Datsun used. There is no water valve, for instance- the core sees full flow all the time and air is diverted around/through the core depending on the temp you want. The cables clip into place (no tools!), the whole thing is simple to install.

 

Were you to swap the entire system in, I'd bet you'd save 15-20 lbs.

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This is the first full "final" install of the dash.

Everything is in place and (mostly) functional...we've never had her this complete before today.

Dash1_1.jpg

 

We ordered a Miata center console on a whim and a prayer and it bolted up as though custom made.

Dash3_1.jpg

 

Dash2.jpg

 

We had to drill one hole in the floor of the console to match a stock Datsun console mount point but the front mated to the dash centerstack perfectly.

The shifter is in reverse in some of the pics and shows the worst case scenario for boot fit.

We thought that at best the Miata part would be a good place to begin with loads of work required but instead, 20 minutes and done!

 

Tomorrow the rear hatch area gets sound treated and the panels/carpet installed.

There will be some aesthetic issues to deal with- we have no idea how to approach the strut tower finishing and our seat belt retractor reels need some attention visually.

We very well may paint the seats also.

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We finished the install of the sound mitigation material in the hatch area and for the first time ever, put all the interior panels in.

I know it's been at least 10 years, and perhaps longer, since she's been this complete.

We're missing the two lower b-pillar pieces and the cover plate for the hatch, we'll probably make them from abs sheet covered in something suitable.

The two primary aesthetic issues are the door panels and the strut towers and right now, we have no idea.

Many thoughts but no firm direction yet.

final1.jpg

 

We consider the Prelude seats to be temporary and thus were willing to risk painting them to better match the rest of the cabin.

Used Duplicolor Flat black vinyl & fabric paint which worked as advertised...we're pretty happy. The fabric does feel rougher but not objectionally so, and some folks say that the effect lessens over time but really, we just wanted the color to match better and it does, so thanks Duplicolor.

final3.jpg

 

final2.jpg

 

Tonight a snow storm moves in which could drop as much as 16" by Sunday night.

Monday morning the Z begins life as a daily driver.

Should be interesting.

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And the parade of piddly shit begins.

Our first float features the heater core:

core3.jpg

 

This is our replacement heater core, I have no idea where Sigfrid got it, so I don't know if it's OEM or not.

At any rate, the original was brass with permanently mounted bungs, this one's aluminum and the bungs are removable. Just like the brass, these alloy tubes are too flimsy and misshapen to do much with, so I made new ones out of some scrap Delrin I had. Didn't have a very large piece, which dictated the length, but they'll be fine.

core1.jpg

 

core2.jpg

 

This situation pops up when you start mixing/matching parts...I'm sure those aluminum foil spaghetti arms make perfect sense in the Miata but for us they were a nightmare.

Situation handled, hopefully.

But just the first of many no doubt, I already know of two more projects to finish- figure out a turn signal cancel device (probably going to try the clockspring next) and fit some sort of handle to our hatch release cable. We deleted the stock Datsun hatch lock/pushbutton and fit the cable release latch from an Accord. Now the interior is basically done, we can figure out the best place for a release. The center console is one option, perhaps use the ashtray location or maybe even the recess for the handbrake (which is opposite the Z location)...make it look like there's a reason for it to be there. A second option is on the driver side b-pillar, just below the quarter window. You could open the door and reach the handle without bending over or reaching for the console...an old guys mod.

 

Tomorrow ends the first full week of Sigfrid commuting, about 25 miles each way, I think.

I'm sure he'll have a whole litany of complaints but I'm happy she hasn't burned to the ground and everything seems to be working fine.

I'll hear all about it Saturday when next we meet.

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Wow, what a great looking install! This is very clean and professional looking and seems to fit really well inside the car.

Thank you, the results exceed our expectations...which is nice because it was a lot of work to get here.

We're now ironing out some details- little things like slightly reprofiling the shifter and swapping in a black faced gauge cluster...the kind of things you have to live with the car for a while before noticing.

 

Mechanically, our only real issue is a front end shimmy that appears around 75mph.

It's not terrible but we've been unable to eliminate it and are down to grasping at straws. Sigfrid's idea is hub centric wheel rings and I believe he has some ordered, so we'll see how that goes.

 

In general though, she's a peach.

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The modded heater core was installed and is leak free, so my interior punchlist is down to three items.

-Still need a hatch release lever/handle/knob/whatever.

-Find a timed relay for the rear window defrost. Most of the wiring is in place (the Miata heater control panel has a switch for defrost), I just need the relay.

-Get the turn signals to self cancel.

 

For no particular reason, I started with #3.

 ts1.jpg

 

ts3.jpg

 

This will be the fifth attempt at the steering wheel>switchgear interface, which has proven to be far more finicky than expected.

The problem is the geometry of the stock steering column...our shaft does not extend as far out of the column tube as the Lexus switchgear would like. It's difficult to explain but those two cancel pins must spin perfectly concentric to the steering column with only about 1.5mm clearance and the same tight confines in the switch cavity. If everything doesn't align properly, those pins either drag on the column or bind in the switch holder.

The horn is easy and has always been functional.

 

As Sigfrid resumes a normal work/family schedule, time for the car has become scarcer and we probably won't meet again till next weekend.

Sad for the Z (which continues to run well in daily use) but good for me as my daily driver engine (1990 RX7 w/ 300k miles) finally decided to die. I have a backup engine about 60% ready to go, just need some more parts...and money.

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Work has continued, albeit slowly.

Installed a revamped gauge cluster- water and oil are VDOs  under Miata dials and needles and to heighten the Christmassy effect, the small gauges got red needles...

end3.jpg

 

Fitted a BMW ebrake handle cover and snood...now the button needs attention:

end5.jpg

 

Finally fitted the Kia hatch release mechanism:

end4.jpg

 

And the headlight covers:

end1.jpg

 

She is functionally complete and runs beautifully.

I'm in love.

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The wiper motor and steering column switchgear is from a 1999 ES300.

The switches are made by Niles and used by other manufacturers, in fact, Mazda uses slightly less "deluxe" versions (they typically lack a fog light switch or have less fancy wiper delay options) that look identical. I actually had switches from a Protege but when I saw how perfect the Lexus wiper motor was, I decided the wiper circuit got simpler if I used the motor and switches from the same car.

Do you think this motor can be intergrated into original 240Z wiring like the more popular Honda motor. I Iike the idea of a Lexus motor

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Do you think this motor can be intergrated into original 240Z wiring like the more popular Honda motor. I Iike the idea of a Lexus motor

Sorry, no idea.

I never intended to use ANY of the stock wiring or devices, so I am unfamiliar with how the wiper is supposed to work originally.

IIRC, a lot of the delay circuitry is actually in the Lexus switch and without it, I don't see how the Datsun switch could make it fully functional.

 

@Greeko...not sure.

I do know they're heavy and I've never cottoned to them much.

I think Sigfrid got them from Tire Rack, but it's been so long I can't remember.

 

Most of my car energy has been lavished on the RX7 this summer, but the Z has been running so well our neglect hasn't been an issue. We've spent a few weekends making minor tweaks and adjustments but haven't undertaken anything major until a few weeks ago when we decided to make doorpanels.

Naturally, neither of us can sew and we have no real experience...so we made it up as we went along.

We finally got the driver side finished enough to install (sorta):

Door3.jpg

 

Door4.jpg

 

The overall look/feel is just what we wanted but we're still debating the final covering choices.

We'll live with this for a while as the passenger side gets worked on (our process involved expandable insulating foam, fiberglass and spot putty) and see what we think.

 

For the last year (basically, since the car became really usable) we've debated our drivetrain options and still can't decide.

If nothing else, we need a five speed transmission...Sigfrid spends a lot of commute time on the highway and the overdrive would be less frenetic and better for fuel consumption.

We sorta see the acquisition of a trans as a commitment to the stock engine and we're just not there yet.

 

The decision will rest mostly with S. (because it's his money), so I've been tinkering with the idea of an electrical system revamp.

Everything works but having done it once, I can see better ways to do it again and might make that a winter project.

 

She's turning into a pretty sweet car though, I always look forward to seat time because it's so different from the Mazda.

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