Mazda MX-5 NA and NB Aero Guide: Spoiler, Skirts, Arches

One of our best-selling parts is not for a Supra or a Skyline. It is a small roof spoiler for the Mazda MX-5 hardtop. MX-5 owners build their cars to drive, so they ask practical questions: will it stay on, will it fit with my mud flaps, how wide can I go? This guide covers the NA (1989 to 1997) and the NB (1998 to 2005), the two generations most of our MX-5 parts are made for.

The hardtop roof spoiler

The factory hardtop fits both the NA and the NB. Our MX-5 hardtop roof spoiler sits on the trailing edge of the hardtop and turns the roofline into a small fastback lip. It comes in fibreglass (black or white gelcoat) or carbon fibre.

Why some hardtop spoilers will not stay on

The most common complaint we see on owners' forums is not about the spoiler itself. It is about what it sticks to. On many hardtops the rubber seal around the rear window is flat or worn, and the spoiler ends up touching it along a thin line instead of sitting on a proper surface. Double-sided tape on a 1 mm contact line will not hold for long.

Before you fit a hardtop spoiler:

Offer it up dry and look along the joint. You want even contact along the whole length, not a line or a few points.
Check the seal. A hard, shrunken or flattened seal is the usual culprit. Fit a new seal first if yours is tired.
Clean properly. Degrease both surfaces, then use an adhesion promoter where the tape goes. Tape fails on wax and silicone, not on the part.
Fit at room temperature. Automotive tape needs warmth to bond. In a cold garage, warm both surfaces first and press firmly along the full length.
Leave it alone for a day before you wash the car or drive it hard.

If the contact still looks poor after a test fit, send us a photo before you stick anything. We would rather solve it at that stage than after the tape is on.

Side skirts: Bomex style and others

Bomex style side skirts for the NA are one of the most recognisable MX-5 looks: deeper than the factory skirt, with a clean straight line between the wheels. They come as a left and right pair in fibreglass (black or white), carbon fibre, coloured carbon, or carbon for paint spraying.

Things to check on your car:

Mud flaps. Some aftermarket skirts clash with factory or aftermarket mud flaps, so check before you fit.
Jacking points. A deeper skirt sits closer to the sills where a jack goes. Use a proper pad and lift from the correct points.
Ride height. If your car is very low, a deeper skirt is the first thing to meet a speed bump.

For the NB, the single-piece Mazdaspeed style side skirts give a factory-optional look with no join in the middle.

Wide arches and wings for the NA

To run wider wheels and tyres, you need more room in the arches.

Front wide wings, +35 mm per side, for a properly wide front track.
Rear wings in OEM width or +25 mm, so the rear can match.
Lightweight OEM style front wings if you want the factory shape with less weight.

Wide body work is a bigger job than a spoiler or skirts. Plan the wheels, tyres and alignment at the same time as the arches, and expect the fitting and paint to take longer than the parts themselves.

Bumpers, lips and the rear

NA bumpers: Deuce style front bumper and Deuce style rear bumper.
NB lips: a front lip and a Mazdaspeed style rear lip.
Diffuser: the Top Secret style diffuser with optional fins.
Front corners: aero side diverters.

Which parts for which build?

Road car: a hardtop spoiler, a front lip and side skirts. Small parts, a big change in looks, nothing that will catch on a driveway.
Track day car: add a front splitter with support rods and a diffuser, and think about the balance between the front and the rear. Our front splitter guide explains why.
Show or wide body build: the arches, bumpers and skirts together, ideally all from one maker so the lines match.

Fibreglass or carbon? For parts you will paint to match the car, fibreglass gives you the same shape for about half the price. We compare the two in fibreglass vs carbon fibre body kits. Browse everything we make in the MX-5 category.

FAQ

Does an MX-5 hardtop spoiler fit both NA and NB?

The factory hardtop is shared by the NA and the NB, so a spoiler made for the factory hardtop fits either car. Aftermarket hardtops can differ, so check yours before ordering.

Why does my hardtop spoiler not stick properly?

Usually because the rear window seal is flat or worn and the spoiler only touches it along a thin line. Check the contact with a dry test fit, replace a tired seal, degrease, use adhesion promoter and fit in a warm place.

Will Bomex style side skirts fit with mud flaps?

Not always. Some deeper skirts clash with factory or aftermarket mud flaps. Test fit the skirts before drilling or removing anything.

How much wider are the MX-5 NA wide arches?

Our front wide wings add 35 mm per side. The rear wings come in OEM width or +25 mm per side.

Are MX-5 body parts sold as pairs?

Yes. Where a part has a left and a right side, such as side skirts or wings, the price is for the pair.