Fiat 124 Spider to ND Miata Compatibility / Interchange Guide
Posted by Esteban R on Jul 18th 2019
Comprehensive guide showing which parts from a 2017+ Fiat 124 Spider fit a 2016+ ND Mazda Miata, and vice-versa.
While the Fiat 124 Spider looks significantly different from the 4th generation (ND) Mazda Miata, it is, in fact, based on the Miata chassis. While Fiat did a great job of trying to differentiate its version with its exterior styling, its own 1.4L Turbo engine, and slightly disguised interior, there are still many parts that are exactly the same, or at least cross-compatible between both cars. That's no surprise, considering they are built alongside each other at Mazda's Hiroshima, Japan plant. What does that mean for us Miata / 124 Spider owners? Greater parts availability, knowing which parts are directly interchangeable, and, more importantly, the ability to customize our cars using OEM parts from the other manufacturer.
This compatibility guide is meant to be a reference point for ND Miata and Fiat 124 Spider owners looking to upgrade or replace certain parts, with parts from the other manufacturer's counterpart. Parts that are a direct bolt-on fit will simply be marked "direct fit", while parts that require other components or modifications will have more detail.
Convertible Soft top: Direct Fit. All trim levels of the 124 Spider use the same soft top as the Grand Touring (GT) Miata, which has an extra inner liner for insulation and sound deadening. The Miata Sport and Club top will still fit a Fiat.
Soft Top Latch: Both the front latch and the rear latch / release mechanisms are the same.
Soft Top Weatherstripping / Seals: Direct Fit, same parts.
Windshield: The windshield on the Fiat is apparently thicker than the one on the Miata. We have yet to verify on our own if they are cross-compatible, but would be willing to guess that they are as long as the corresponding windshield seal is used as well.
Plastic Windshield Surround Trim (3 pieces): Physically the same, although the Fiat ones come in more diverse colors. These are directly compatible, but it's nearly impossible to remove the trims (the center one mainly) and keep their mounting tabs intact for reuse.
Wiper Cowl: Direct fit, same parts.
Wiper Arms: Direct fit, same parts.
Wiper Motor / Wiper Transmission: Direct Fit
Door Mirrors: They look almost identical, but the base on the 124 Spider ones is slightly larger.
Window Glass: Physically the same, but there would be a visible mismatched Mazda or Mopar logo if used on the on the other car.
Exterior Door Handles: Direct Fit
Door / Window Moldings (top of door): Direct Fit
Door Sill Plates / Scuff Plates: Direct Fit
Fender Marker Lights: Direct Fit
Antenna: The antenna itself is a direct fit, but the mounting base differs due to the different contours of the quarter panel.
Rear Bumper Marker Lights / Reflectors (red): The 124 Spider Abarth uses the same marker lights as the ND Miata, but the other model 124 Spiders use a different style.
Wheels and Tires: While differing in style, all the wheels and tires and directly compatible across both cars. The exception being on cars that came with the factory Brembo brakes, which require the ND BBS wheels or 124 Abarth wheels for caliper clearance.
Hood, Bumpers, Fenders, Doors, Sideskirts (rocker panels), Trunklid, Headlights, Taillights, Running Lights, Gas Lid, Third Brake Light, Quarter Panels: Do not interchange.
Seats: Direct Fit, as long as you have the same options on your car, in particular the seats that have speakers integrated into them. We installed ND Club seats into a 124 Abarth and 124 Abarth seats into the ND Club with no adverse effects. Even though the ND didn't have seat heaters like our Abarth did, they still plugged right in and the other electronics on them worked (airbags, speakers, occupancy sensors).
Seatbelts: Direct Fit.
Seatbelt Buckles: Direct Fit
Steering Wheel (manual transmission): Direct Fit. Mounting and electronics are the same.The rim of the Fiat ones are thicker than the Miata ones, and the 124 Abarth ones have different styling, so we'd consider those to be an upgrade in the Miata.
Steering Wheel Airbag: Interchangeable, but the logo would be different, not recommended.
Clockspring: Direct Fit
Dash panel: The Fiat 124 Spider dash panel differs from the ND Miata one, If you wanted to use a Fiat dash panel on a Miata you'll also need to change the A-Pillar covers, cluster hood, rectangular dash vent and door panels for a complete look, and vice versa.
Passenger Airbag: Direct Fit
Lower Dash Trim (passenger side): Direct Fit, as long as you're using the same style (all black one piece found on ND Sport models, or two piece black with red stitching found on higher end models).
Cluster Hood / Cover: Not interchangeable unless you're also changing the dash panel and various other items as noted above in the Dash section.
A Pillar Plastics: Not interchangeable unless you're also changing the dash panel and various other items as noted above in the Dash section.
Door Panels: The door panels themselves bolt into place, but there are some caveats. First, the ND Miata door panels have 2 mounting screws in the door pull area, and the Fiat has 3 of them. We did find that the ND had the provision for the 3rd mounting screw already there, so it will bolt on. Secondly, the inner door handle for the Fiat is larger, so if you're mounting Miata door panels on a 124 Spider you'll need the Miata inner door handles as well. The window and mirror switches are a direct plug in, no issues there.
The biggest concern comes from the way the front of the door panel fits against the dash area. The Miatas that come with the painted upper door panels (Club and GT) have a small painted trim piece on the dash, and the Fiat 124 has a small trim piece in this area as well. Those trim pieces line up perfectly with their respective door panels, but not at all with the other model's door panel. In order to install those small pieces you'd also need to use the a-pillar covers and dash, along with a couple other smaller pieces from the other model. Without going through that much expense and trouble, the better fitting scenarios of the two is the Fiat door panels on the Miata, but it's still something we wouldn't feel good about on such a new car.
Interior Door Handles: They have different shapes. They fit the other car with use of the other car's door panels.
Window Switches: Direct Fit
Circular AC Vents: Direct Fit
Rectangular (center) AC Vent: Not interchangeable unless you're also changing the dash panel and various other items as noted in the Dash section above.
Climate / AC Controls: The auto climate controls are directly compatible from one car to the other, as long as the car has the auto climate controls option. For cars without automatic climate controls you'll find that the Fiat has silver trim rings, whereas the ND Sport and Club have black trim rings. The Fiat unit is directly compatible and a nice touch in an ND Miata.
Instrument Cluster: The Fiat clusters and ND Miata soft top clusters are compatible, but you will have warning lights on. We tested an Abarth 124 cluster (with the awesome red tach) on an ND Club, and the basic cluster functions work, but there were several warning lights. The Fiat Battery Management System (BMS), and blind spot monitoring lights were on, this is inevitable at this point due to different option packages between Mazda and Fiat, as well as the specific manufacturer lights, like the Fiat BMS. We'd think it would be worthwhile on a track car, but not necessarily on a street car.
Center Console: Direct Fit, same part.
Center Console Infotainment Controls: Direct Fit, same part.
Infotainment Screen: The screen unit itself is physically the same, although we suspect that the firmware is manufacturer specific due to changes in options, safety features, graphics, service intervals etc, so we do not recommend using one from the other brand.
Shift Knob, Manual Transmission: Direct Fit. Although they have different shapes, they are the same height and have the same thread pitch.
Shift Boot, Manual Transmission: Direct Fit. The Fiat and Mazda ones have varying stitching colors, but are physically interchangeable.
Shifter Surround: Manual transmission ND Miata and auto or manual transmission 124 Spiders without Sport mode are the same. Auto or manual transmission Sport more equipped 124 Spiders have the same shifter surround as automatic transmission ND Miatas.
Cupholders: Direct Fit, same parts.
Parking Brake / E-brake Handle: Direct Fit. The Fiat and Mazda ones have varying stitching colors, but are physically interchangeable.
Parking Brake / E-Brake Boot: Direct Fit. The Fiat and Mazda ones have varying stitching colors, but are physically interchangeable.
Combination Switch: Direct Fit. Just make sure you're using the ones from a car with similar options (like automatic headlights).
Sunvisors / Interior Windshield Trim Panel: Direct Fit, same part.
Dome Light: Direct Fit, same part.
Rearview Mirror: Direct Fit, as long as you're using the same style your car came with, basic or Homelink.
Carpet: Direct Fit, same parts.
Floor Mats: Direct Fit. You'd have the wrong logo though. Non-branded aftermarket ones would be compatible for both models.
Pedal Set: The brake and clutch pedals are interchangeable, as are the pedal covers by themselves. The accelerator pedal assembly may not be 100% electronically compatible (different part numbers on the electronic portion), but the part of the pedal that moves is removable and interchangeable.
Steering Column Plastic Surround: Direct Fit
Plastic Trim Behind Seats / Under Soft Top: Basically all the trim behind the seats is exactly the same between both models. One exception being the storage cubby in the center, behind the seats, the 124 Spider and 2019 ND don't have a CD player here, so they have a larger storage cubby and a blanking plate, both of which fit a 2016-2018 soft top ND Miata. **RF Miatas will have different plastic back here.
Roll Hoop Covers: Direct Fit. Different colors between manufacturers, can be interchanged though.
Factory Roll Bar / Roll Hoops: Direct Fit, same part.
Windblocker: The windblocker on the Fiat 124 Spider and soft top models are the same part, direct fit.
Window Regulators: Direct Fit
Engine / Transmission / Differential
Engine and all accessories attached to engine: Completely different design. The Miata uses Mazda's 2.0L Skyactiv four cylinder, which is naturally aspirated, while the 124 Spyder uses Fiat's 1.4L Multiair turbocharged four cylinder.
Motor Mounts: Direct Fit. **the motor mount brackets that bolt onto the engine are different though**
Airbox: Not interchangeable.
Coolant Overflow Tank: Not compatible
Radiator: Not interchangeable, different mounting points for fan.
Radiator Cooling Fan: Not interchangeable, different mounting points for radiator mounting.
AC Condenser: Not interchangeable.
Fuel Pump Assembly: Not interchangeable
Exhaust: All exhaust components are unique to each model and are not directly compatible.
Automatic Transmission: Not interchangeable
Automatic Shifter: The knob portion is different, but the rest looks the same, we'll update this once we can physically verify if they're interchangeable or not.
Manual Transmission: Not interchangeable, the Fiat uses a version of the NC Miata 6 Speed Manual Transmission. The Fiat 124 Spider transmission does not interchange with the NC Miata though, due to exterior differences:
Manual Shifter Assembly: Not interchangeable
Flywheel: Not Interchangeable
Clutch Pressure Plate and Disc: Not interchangeable
Powerplant Frame (PPF), Manual Transmission: Direct Fit
Powerplant Frame (PPF), Auto Transmission: Pending Verification
Manual Driveshaft: Not Compatible. They have the same splines, but the 124 Spider driveshaft is about 1" longer.
Automatic Driveshaft: Pending Verification
Differential, Manual Transmission Car: The ND Miata uses a 2.866 gear ratio, while the 124 Spyder uses a 3.45 gear ratio. Exterior dimensions and axle splines are the same, so they are cross-compatible.
Differential Mounting Bracket, Manual Transmission Car: Direct Fit
Axles, Manual Transmission Car: Slightly different design in the center, but are the same length and splines on both end match up with the other manufacturer's axles.
Suspension / Brakes / Wheels
Front Subframe: These are almost identical, except for the front horizontal piece that goes to the front of the frame rails. The Fiat version is taller in this area for intercooler clearance. The 124 Spider subframe also has an extra mounting tab near the crank pulley that the Miata one does not have.
Rear Subframe: Direct Fit
Steering Rack: Direct Fit
Strut Tower Bar: Direct Fit
Sway Bars: Direct Fit. They have different markings on them, presumably for different stiffness ratings.
Front Upper and Lower Control Arms: Direct Fit
Rear Control Arms: Direct Fit
Front Spindles / Hubs: Direct Fit
Rear Spindles / Hubs: Direct Fit
Bilstein Shocks: Physically compatible, but with different part numbers, presumably for internal differences.
Springs: Physically compatible, but with different paint code markings, presumably for slightly different spring rates.
Top Hats / Shock Mounts: Direct Fit
Shock / Spring / Top Hat Assemblies: Direct Fit. Will have a difference in spring rates / and or valving.
Brake Calipers / Brackets: Direct Fit
Wheels: While differing in style, all the wheels and tires and directly compatible across both cars. The exception being on cars that came with the factory Brembo brakes, which require the ND BBS wheels or 124 Abarth wheels.
Thank you for reading, we hope you've found this guide helpful. Feel free to share this article via the quick links provided below, or via the URL.
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We wrote this guide as a reference for parts that we were able to physically check fitment on or verify part numbers on. Please use your best judgement or seek the advice of a certified mechanic if you have any questions or doubts before purchasing or installing parts from a Miata or Fiat that is a different year or model than yours. We are not responsible for any financial loss, injury or death arising from the improper installation or modification of your car and/or parts.