RR Motorworks

Will it fit or not?

A Compatibility Guide between
'90 - '97 (NA) and '99-'05 (NB) MX-5 Miatas

(Note: 2006 & later (NC) MX-5s are a ground up redesign. There is little, if any, compatibility.)

This is a work in progress and we expect it will grow as we do more and more work and experimentation on the Miata. Meantime, if you have information to add to this list, please let us know!

Does not fit
<blank> No information
Part NA fits NB NB fits NA Notes

Suspension, Wheels, & Brakes

Brake pads      
Coilover shocks      
Brake Caliper    
Lower Control Arms Yes Yes Sway bar mount with NB has a larger single mounting tab
Upper Control Arms/Ball Joints Yes Yes NA & NB front upper control arms are identical- BUT the ball joints are not. The threaded rod is 1/4" longer on the NB control arm. So the ball joints would need to be swapped to make them interchangable.
Rear knuckle Yes   The dust shield appears to be the only difference, camber stayed the same caliper mount bracket, caliper and rotor from the NB bolted right up to the NA knuckle
Steering rack (Power and manual) No No  
Front hub Yes No If the NA hubs are to be added to the NB they must be installed with NA upper control arms (see ball joint issue above).
Wheels Some special edition models equipped from the factory with 16" wheels may not be able to handle 14" or 15" wheels.


Nardi Steering Wheel N/A Clocksprings are different, connections are different, different trigger mechanisms.
Dashboard   Yes We've been told it has been done.
Brake Handle Yes Yes  
Dashboard, Inst. cluster   See notes 1.8l NA and NB dashes are mechanically interchangeable. They attach with the same 10 or so fasteners. The electrical connections are not interchangeable, but are easily modified. And of course the console should also be exchanged. NA and NB instrument clusters are physically interchangeable with minor modifications. The NB dash can be easily modified to accomodate the NA cluster and speedometer cable. The electric speedo drive of the NB is a very easily retrofit to NA cars, but the rest of the electrical conversion requires researching NA and NB wiring diagrams & a few dozen wire splices.
Shift knob  
Seats yes yes One reader put seats off a 2000 into his '94 with no trouble.Another had no problem dropping seats off a '93 into his '01.
Seat Belts   See notes

Used 4 original bolts and spacers since the NB spacer where different. The 99 reel assembly is taller than the assembly from 92. I was able to enlarge the hole but it took several hits with a very large hammer to make the opening big enough, its definitely not a direct bolt in.

Another reader writes: I was able to continue using my '93 seat belts with the '97 seats but if I had bought '93 seats to install in a '97, the seats belts would have required modification such as drilling etc. The belt receivers on the '97 were mounted to the seat and the belt receivers on the '93 were mounted to the transmissiom tunnel. Also the male and female ends did not match.

Engine & Drivetrain

Engine block See notes See notes NA 1.8l Miata blocks (94 - 97) have the oil and water ports used to supply the turbo on the '04 and '05 MSM. They are unused & plugged, but I have confirmed that the union bolts of the MSM match the threads of the NA 1.8l blocks.

The normally aspirated NB blocks do not have these ports, so the normal NB block is not fully compatible with the MSM.

The 2002 engine itself is a direct fit to a 1994 starter, transmission, and subframe (provided you have 2002 mount brackets), but seems to reduce clearance up front. Intake routings on turbo kits become a bit more difficult, but workable if you don't have an A/C fan.

Manual Gearbox Six speed included
Manual Shift Lever  
Oil filter  
Air filter   The difference is slight, but the parts are not interchangeable.
Fuel filter The NB uses quick disconnect plastic fittings and plastic fuel lines that have dedicated ends. If you damage a NB fuel line, you must order that specific replacement part. The NA uses generic rubber fuel line available anywhere and normal spring clamps to secure the lines to the filter.
Spark Plugs  
Ignition wires Only compatible through 2001.
Thermostat & housing No No  
Timing Belt Yes Yes  
Alternator   See notes Alternator belt fits as well. We've been told it may require a pully change.
Water Pump   Yes  
Crank Angle Sensor Yes   CAS from a 1994 is a very easy retrofit onto a 2002 engine, and likely onto a 1999 engine as well.
Cam gears   Yes Also cam seals, pulley/balancer
Fuel Rail No No Bolts on, but leaks heavily.
Coolant Hoses   Yes Upper and lower radiator hoses fit. Others unknown.
Radiator No No  
Oil drain washer No No Different size washers & drain bolts
Torsen diff   See notes

A Torsen differential and axles from an '04 MSM will bolt up to a 93' with the exception of the driveshaft bolts which are slightly bigger.

Torsen Diff   '99 Torsen (plus half-shafts and drive shaft) fitted to '92
MAF No No  
Water temp sensor See notes   Fits mechanically, but electrical connector is different.
Oil pressure sensor See notes   Fits mechanically, but signal compatability is unknown.
Battery   Stock battery fits. Aftermarket unknown.
Oil Pan See notes NA oil pan will not fit NB engine there are lobes in the windage/ baffle plate on the nb, mating surfaces are straight/ longitudinally parallel in the NA, NB has little semicircle reliefs on the inner edge of the face. Presumably the nb would fit an NA just fine, bolt patterns the same.


Wiper refills  
Brake light bulb      
Tail light bulb      
Front parking light bulb      
Catalytic Converter
& Catback
Exhaust manifold all the way back to the muffler is completely different. Also, there are differences between the NB manual and automatic exhausts. They are not interchangable.
Header See notes Exhaust manifold all the way back to the muffler is different. However, it has been reported that you can also fit a whole NA system to an NB with only minor modifications. "The manifold is a straight swap, and all you need to do is make yourself a hanger for the mid section, and bend a hanger on the muffler and get a slightly longer rubber hanger as the hanger on the subframe is in a slightly different position on NAs and NBs."
Windblocker N/A with mods Most aftermarket windblockers from the NA should fit the NB. See article.
Radio   "I have fitted a double DIN original Mazda/Clarion cd/radio/cassette unit from a 2001 MX5/Miata to a 1992 NA model. I did have to remove the original metal radio cage that was in place securing the aftermarket single DIN that was in tha car when I got it. After that was out and carefully tracing and connecting the wiring to the double DIN unit connector it just popped right in."
CD Player (in dash)  
Radio trim

The audio system trim, sometimes called the tombstone, is completely different.

Hardtop Some additional hardware required.
Soft Top   The soft top by itself will not fit. If the entire soft top frame is replaced, it will. (The NB top has been successfully retrofitted to an NA frame, though it requires some modification. See the Garage)
Tonneau (factory) For 99/00 only, the dealer accessory tonneau has no "muff" for the headrest. This is much more attractive, but can be used only because of the lower height of the OEM seatback used ONLY THOSE 2 YEARS, and also requires that each seat be slid fully forward and fully reclined, to permit the tonneau to be installed. Use of these tonneaus on 2001 thru 2005 cars is possible only with 1999/ 2000 seats. Stretching the tonneau over the 03 driver seat requires a problem level of tension on the fabric and dash "lift-a-dot" pins. Putting 99/00 seats into the NA car might be possible; needs a trial.
Boot Cover Uses snaps instead of Tenax fasteners. Some owners have successfully replaced the NB snaps with theTenax fasteners removed from NA cars.
Door speakers Different size openings. Could fit with metal cutting.
Sill Plates (Scuff Plates)   Minor drilling required.
Body panels Most body panels are not interchangeable. Note: NB front nose for the '01 and later will not fit on the '99/'00.
Glovebox lock Some Some '90-'93 glovebox locks are not interchangeable with '94-'97
Eyeball vents  
Gas Cap    
Interior body bracing The dimension between the seatbelt bolts on the 1990 is 44-13/16" while the 1994 is 41-5/16".
Subframe braces   NA and NB subframes, front and rear, are interchangeable w/ their attached assemblies. I.e. the front subframe and steering gear can be interchanged as assemblies (uprights should also be exchanged to retain improved NB steering geometry).
Door panels   Late model NB door panels & cable operated lock mechanisms (01 & up?) require significant modification to the NA door panels.
Door windows   I would like to report that side windows (big ones - I don't know about the small rectangular ones) from NB fit NA. I have made a switch like that in my NA '1997 and it looks and works great. - Grzegorz Dubicki


Strut Brace Checked Dealer Alternative Brace
Rear brace Cannon, Racing Beat OK. Others not tried, but likely fit.
Grill Some N/A Depends on model. Friction fit model incompatible.
Trunk Lift N/A Checked Team Miata. ('99 w/ cruise control requires minor mod.)
Front Sway Bar Mounts are turned 90 degrees. Will work if you use adjustable end links.
Rear Sway Bar Jackson Racing checked.
Tonneau (aftermarket)   Depends on attachment method. Some will fit, others will not.
CRI Air Horns N/A  
Fitted Car Cover   We've been told they don't fit. We tried a cover custom fitted for the NA. It fits fine on the NB.
Roll & Style Bars Some N/A Hard dog fits: the company reports that the second generation Hard Core Bar will fit both NA and NB, it has 1 3/4 inch tubing. The first generation 1.5 inch tubing NA bar will not fit the NB.
Autopower currently does not. New model in design.
Others unknown
Brake Boots  
Shift Boots   Very tight fit. Not a good idea.
Steering Wheel Cover Steering wheels are different sizes.
Steering Wheel Hub Adapter Fit problems reported.

Additions to this list? Contact us!

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19 February, 2024

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