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NB Miata Compatibility Guide (NB2 to NB1)

NB Miata Compatibility Guide (NB2 to NB1)

Posted by Esteban R on Dec 19th 2018

The comprehensive guide to knowing which parts from a 2001-2005 Miata fit a 1999-2000 Miata.

This compatibility guide is meant to be a reference point for 1999-2000 (NB1) Miata owners looking to upgrade or replace certain parts with items from the facelifted 2001-2005 (NB2) Miata. 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.

**This majority of this guide only references non-Mazdaspeed models**. For parts specific to a 2004-2005 Mazdaspeed, the last section will cover which parts will fit other year Miatas.


Exterior

Headlights: Bolt on, but require used of NB2 front bumper to fit correctly. The NB1 headlight design only has one bulb for low beams and high beams, while the NB2 style uses two separate bulbs, so wiring modifications will also be needed.

Front Bumper: Fits with use of NB2 headlights. For best fit, use bumper-to-fender mounting clips from your NB1 front bumper and source some NB2 fender liners as well.

Fog Lights: There are two styles, 2001-2003 and 2004-2005, neither of them fit on an NB1 front bumper. If doing an NB2 front bumper swap you'll need to rewire your old NB1 foglight connectors or run new wiring if yours didn't come from the factory with foglights.

Front Bumper Spoiler / Lip: Does not fit NB1 front bumper

"Large" or "Tupperware" Sideskirts and Mudflaps: Direct fit, requires use of OEM or OEM style hardware for best fit and finish.

2003-2005 Cloth Soft Top with Frame: Direct fit

Taillights: Direct fit as long as you're using the small taillight harnesses from an NB2. Make sure the NB2 taillights you source have these included.

Doors: Though very similar in appearance, there are some differences in the door opening / lock mechanisms and door panel mounting points. Best option is to source an NB1 replacement door.

Fenders, Hood, Side Mirrors, Rear Bumper, Trunklid: Direct fit, no changes.


Interior

Seats: Direct Fit

Door Panels: The placement and mechanisms of the inner door handle are different, as well as the door panel mounting points. A good amount of modification is necessary to get these to fit.

Window Regulators: Direct Fit

Center Console: Direct Fit, reuse your existing NB1 window switch.

Window Switch: The NB2 window switch adds the "auto down" function to the driver's side. While physically the same, they are wired differently, so rewiring will be necessary to fit an NB1.

Three Spoke Steering Wheel / Airbag: Steering wheel and airbag combo are a direct fit to any NB1. Steering wheel or airbag by themselves are a direct fit to an NB1 that came with the three spoke steering wheel from the factory.

Dashboard: Bare dashboard is a direct fit. Harnesses will be year specific and switches will have red backlighting, so reusing your old ones will be necessary.

Double DIN Radio: Not a direct fit because the harness connector is different.

Instrument Cluster: The NB2 cluster has white gauge faces and red backlighting. There are a couple ways to go about adapting them into an NB1, from slight rewiring to install the complete cluster, to changing only the gauge faces, to changing the gauges themselves. If you choose to install the whole cluster you'll need to reuse your bulbs or green bulb covers to retain green backlighting. You should also change out the odometer module to retain the correct mileage. Alternatively, you can use a cluster from a 2000 Special Edition, which has similar gauge faces, but with green backlighting and no need for rewiring.

Shift Knob: Direct Fit

Leather Parking Brake Handle: Direct Fit

Silver AC Vent Trim Rings: Direct Fit

Radio Surround / Shifter Trim: Direct Fit

Special Edition Pedal Sets: Direct Fit. Make sure you source pedals that are compatible with your car (auto or manual, or cruise / no cruise).

Bose Windblocker with Speakers: Bolts in directly, but the NB1 was never offered with these, so you will need to run custom wiring to the speakers.

Main Floor Carpet: Direct Fit

Carpet Behind Seats: Use a replacement from a 2001-2002. The 2003-2005 models came with LATCH child seat anchor points behind the passenger seat, so the carpet will have the cutouts for these that will be visible on your NB1 after installation.

Carper Underneath Soft Top: Direct Fit

Seatbelts: Not compatible. The NB2 seatbelts have a pyrotechnic pretensioner that the NB1 does not have the wiring for.

Combination Switch (headlight / wiper): Direct fit. Cruise Control and Non-Cruise available so make sure you're replacing yours with the same style.

Ignition Switch: Not compatible.


Engine / Drivetrain

VVT Engine: For best results make sure the engine you source is complete with motor mount brackets, intake manifold, fuel rail, injectors, injector harness, and ignition coils with connectors. From your NB1 you will need to reuse your accessories (alternator, power steering pump, AC compressor), throttle body, and engine to ecu harness. Wiring changes include wiring in your new coilpack connector plugs and relocating the cam sensor plug from the front of the valve cover to the back. You can use your existing exhaust manifold and EGR tube, upgrade to the NB2 manifold or use an aftermarket NB1 header at this time.

If you're installing an NB2 VVT engine into your NB1 because it was more affordable and more readily available than a 1999-2000 engine, then you can leave the VVT solenoid unplugged and run the engine in its default timing setting. 

If you're installing an NB2 VVT engine into your NB1 because you're looking for a performance gain, then we suggest an aftermarket ECU or VVT Tuner to control the VVT timing of your new engine.

VVT Head: Because the main differences between the NB1 and NB2 engines are in the cylinder head itself, everything above from the engine swap, except the motor mount brackets, applies. You would need the complete cylinder head with valvetrain, cams, vvt actuator, valve cover, coils, vvt solenoid and vvt oil lines. At this point, in all honesty, it might make more sense to get the full NB2 engine, which will also have higher 10.0:1 compression and the higher flowing oil pump needed for the VVT system. 

Valve Cover: Not compatible with NB1 engine

Ignition Coils: Not compatible with NB1 engine unless a Mazdaspeed Miata Valve cover is used. This is because the Mazdaspeed uses the same style BP4W head, but with the newer style Ignition Coil setup. Will also need the wiring connectors from the NB2 coils.

Tubular Exhaust Manifold: Popular upgrade for NB1 Miatas. At a minimum you will need the manifold and EGR Tube for a Federal Emissions car, and for an OEM finished look we also recommend the heat shields as well. On a California emissions car you would need the same parts, plus extended oxygen sensor wires (available from Racing Beat), and an extra o2 sensor bung to weld on after the midpipe-mounted catalytic converter.

EGR Tube: Will not fit unless used in conjunction with an NB2 exhaust manifold.

Exhaust Downpipe: Direct fit, no change.

Exhaust Mid-pipe: Theoretically should be a direct fit onto a manual NB1, but we've never tried it ourselves. We'd like to see if the o2 sensor wiring and calibration will work properly before making a recommendation.

Exhaust Muffler: Direct fit for manual transmission cars, no change in design. NB1 automatic transmission cars have a smaller size midpipe to muffler flange, so it will not fit without modification. 

EGR Valve: Not compatible, different part number

Engine Block (bare): Direct fit

Crankshaft: Direct Fit

Rods: Direct Fit

Pistons: NB1 has 9.5:1 compression ratio, NB2 has 10.0:1 compression ratio, but they are interchangeable. 

Oil Pan: NB2 oil pan fits as long as factory NB2 Main Bearing Support Plate (MBSP) is also used. The MBSP is a direct replacement for the NB1 oil pan baffle. Make sure to get the 8 bolts that attach the MBSP to the block, also make sure to use new front and rear half moon oil pan seals for an NB2.

Oil Pump: NB2 flows more, and is a direct fit.

Alternator: NB2 is rated for 80 amps vs 70 amps for the NB1. Direct fit. 

Intake Manifold: Fits with some modifications, but not recommended (not an upgrade).

Intake Manifold Solenoid: Direct fit, same part.  

Throttle body: Direct fit, same part. Make sure you get a BP4X for an automatic car or BP4W for a manual car. 

Injectors: NB2 injectors flow more, but are a direct fit.

Fuel rail: Not a direct fit. 

Crank Pulley: Direct Fit

Crank Pulley Boss: Direct Fit

Crank Gear: Direct Fit

Water Pump Pulley: Direct Fit

Camshaft Gears: Exhaust cam gear is a direct fit, but the intake cam gear is not compatible due to VVT.

Intake Camshaft: Not compatible

Exhaust Camshaft: Direct Fit on exhaust side (same part). Will also work for the "Exintake" cam swap that involves using an exhaust cam on the intake side of an NB1 Miata (this requires modification to the cam and cam gear).

Camshaft Sensor: Direct Fit

Crank Sensor: Direct Fit

Thermostat Housing: Direct Fit

Starter: Direct Fit

MAF: Not compatible, different part number and calibration.

ECU: Not compatible, the NB2 ECU's have an immobilizer system that the NB1's don't have and different wiring leading to the ECU. 

Air Box: Direct fit, reuse your NB1 MAF.

Intake Tube: NB2 has a "resonator" attached to the intake tube, but is a direct fit on an NB1.

Radiator: Direct fit, same part. If you have an automatic NB1 make sure to get a radiator from an automatic NB2.

Engine Cooling Fan: Direct Fit

AC Fan: Direct Fit

AC Compressor: There are different style AC compressors 2001-2002, 2003, and 2004-2005, none of which are directly compatible with an NB1.


Transmission / Differential

5 Speed Manual Transmission: Direct fit, no change.

6 Speed Manual Transmission: Direct fit, make sure you get the shifter from the same car as the transmission.

Automatic Transmission: Not compatible

Shifter 5 Speed: Direct fit, same part.

Shifter 6 Speed: Only early 2001's have the same shifter as the NB1 6 speed transmissions. Mid-2001-2005 Came with a larger shifter that is not backwards compatible. 

Flywheel: Direct Fit

Clutch Pressure Plate & Disc: Direct Fit

Powerplant Frame (PPF): Direct Fit

Speedo Sensor: Physically compatible, sensors from cars with different gear ratios came with different calibrations, so make sure to use the most applicable one. 

Driveshaft: Direct Fit. Make sure to use one from the same transmission type as your car ( auto or manual).

Differential: Physically compatible. For notes on different gear ratios found on different years and models see: 

Miata Torsen Buyers Guide

Differential Housing: Direct Fit

Axles: Direct fit. Make sure to get NB2 axles from an ABS equipped car if you have ABS on your NB1.



Suspension / Brakes / Wheels

Front Subframe: Direct Fit

Rear Subframe: Direct Fit

Steering Rack: Direct Fit 

Power Steering Pump: Direct Fit

Power Steering Reservoir: Direct Fit

Strut Tower Bar: Direct Fit

Sway Bars: Direct fit 

Front Lower Control Arms: Direct Fit

Front Upper Control Arms: Direct Fit. Make sure to get ones from an ABS equipped car if you have ABS on your NB1.

Rear Lower Control Arms: Direct Fit

Rear Upper Control Arms: Direct Fit

Front Spindles: Direct Fit. 2001-2002 Base model ones are identical. 2001-2002 LS, 2001-2002 Special Edition models and all 2003-2005 Miatas came with larger "Sport Brakes" which have a larger dust shields on them. If you get ones with the larger dust shield you can choose to keep the larger dust shield on there, or reuse your NB1 dust shields. 

Rear SpindlesDirect Fit. 2001-2002 Base model ones are identical. 2001-2002 LS, 2001-2002 Special Edition models and all 2003-2005 Miatas came with larger "Sport Brakes" which have a larger dust shields on them. These will still fit, but will look a odd when run with the smaller NB1 brakes. 

2001-2002 Base Model Brakes: Direct Fit

"Sport Brakes" Brakes: These came on 2001-2002 LS, 2001-2002 Special Edition models and all 2003-2005 Miatas. You will need the calipers, larger caliper brackets, rotors, pads and front brake lines in order to fit an NB1 correctly. Dust shields will have to be modified to accommodate the larger rotors. *factory 14" wheels and some 15" aftermarket wheels will not clear these brakes*

Wheels: Direct Fit

Spare Tire / Wheel: NB2's equipped with "Sport Brakes" came equipped with a larger 15" spare tire / wheel to clear the bigger brakes. These are a direct fit to an NB1.



Mazdaspeed Miata (2004-2005)

This Section is dedicated to the parts that were specific to the 2004-2005 Mazdaspeed Miata (MSM).

Front Bumper Lip: Only Compatible with 2001-2005 bumpers, not compatible with 1999-2000 bumpers.

Rear Bumper Lip: Direct fit for any 1999-2005 rear bumper.

Trunk Spoiler: Direct fit for any 1999-2005 trunklid. 

Seats: Direct fit for any 1999-2005 Miata.

Door Panels: Direct fit for 2001-2005 Miata. 

Pedal Set: Direct Fit for any 1999-2005 with manual transmission and without cruise control. The Mazdaspeed gas pedal does not have the attachment tab for the factory cruise control cable.

Radio Surround / ShifterTrim: Direct fit for any 1999-2005 Miata.

Instrument Cluster: Direct fit for 2001-2005 Miata. 1999-2000 Miatas will require modifications described above in the NB2 to NB1 cluster notes.

Full Engine: The complete engine with turbo components will physically fit a 1999-2005 Miata, but the wiring, ecu intake plumbing and exhaust will not be fully compatible. We strongly suggest an aftermarket ECU and lots of planning ahead when swapping this engine into another year Miata. 

Valve Cover: Fits a 1999-2000 Miata that is being converted to the NB2 / Mazdaspeed style ignition coils. Does not fit a non-Mazdaspeed VVT engine. 

Oil Cap: Direct fit on any 1999-2005 Miata

Turbo Exhaust Manifold / Turbo: Bolts onto any 1999-2005 Miata, but will require many custom and / or aftermarket components for a successful implementation. 

Oil Pan: Direct fit onto an NB2 VVT engine. MSM oil pan fits as long as factory MSM Main Bearing Support Plate (MBSP) is also used. The MBSP is a direct replacement for the NB1 oil pan baffle. Make sure to get the 8 bolts that attach the MBSP to the block, also make sure to use new front and rear half moon oil pan seals for an MSM.

Intake Cam: The Mazdaspeed uses the more aggressive BP5A intake cam, that is a direct fit upgrade for a 1999-2000 NB1 Miata. Does not fit the 2001-2005 VVT engine.

ECU: Not directly compatible with any other NB Miata.

6 Speed Manual Transmission: Direct fit for any 1999-2005 manual Miata. Make sure the Mazdaspeed transmission you get comes with the shifter as well.

Clutch Pressure Plate and Disc: Direct fit onto any 1999-2005 Miata. 

Mazdaspeed Torsen Differential: Direct fit onto any 1999-2005 Miata when used in conjunction with the Mazdaspeed axles.

Axles: Only compatible when also using the Mazdaspeed differential on a 1999-2005 Miata.

Driveshaft: Direct Fit

Muffler: Direct fit onto a any manual transmission 1999-2005 Miata, or a 2001-2005 automatic transmission Miata.

Strut Tower Bar: Direct fit onto any 1999-2005 Miata. Unless you plan on using the extra plumbing that is integrated into the MSM bar, we recommend using a standard NB2 strut tower bar instead.

Sway Bars: Direct Fit onto any 1999-2005 Miata, make sure you use the MSM sway bar bushings and mounting brackets as well. 

Shocks / Springs: Direct fit onto any 1999-2005 Miata.

Wheels: Direct fit onto any 1999-2005 Miata.

2004 MSM Headlights: Direct fit onto any 2001-2004 Miata. There was a wiring change on 2005 Miata headlights, so a closer look will be needed to see if they are compatible if you have a 2005. 

2005 MSM HeadlightsThere was a wiring change on 2005 Miata headlights, so a closer look will be needed to see if they are compatible with your particular 2001-2005 Miata.


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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*Disclaimer*

We wrote this guide as a reference for parts that we have hands-on experience with either installing, or physically checking fitment on different year cars. 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 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.