Introduction: Mazda MX-5 NC1 to NC3.75 Conversion

The purpose of this instructable is to show you what I did to upgrade the front of my 2006 Mazda MX5 to the style of the 2015 models. Usually, this can be achieved by getting new bumper and new headlights and just fiddling a bit with some brackets. From where I live though, it was really hard and expensive to source the new headlights so I decided to use the old ones and adapt the bumper to fit them. The problem when using the old headlights is that they have a different shape and this creates a considerable gap between the bumper and the headlight. To overcome this, rev9 created a conversion lip (see it here) but it's pretty expensive for a lip and it doesn't look impressive either.


  • NC3.75 (2012 -> 2015) front bumper (of course)
  • Fiber glass kit (sheets, resin, hardening agent, brushes, gloves, scissors)
  • Sand paper, misc grits
  • Basic tools
  • Patience

Step 1: Acquiring the Bumper

For me, the new bumper arrived like this. No grill, not fog lights shroud, no tow bar cover. The bumper itself was not expensive but quite tricky to get. It seems not a lot of NC3 models end up in the wrecking yards.This bumper was an OEM one, you could probably find a new aftermarket one but I would doubt how well it would fit.

Step 2: Initial Fitment

The OEM bumper fits perfectly with the body, all holes align, just that there is this huge empty space around the headlights. It can't be seen perfectly here but in the lower left edge there were around 2 cm of space and at the top right edge of the headlight, the bumper extended outside it's smooth surface with still around 2 cm, showing a somewhat ugly surface. This part here could potentially be left out as it complicated the bumper reconstruction quite a lot.

Step 3: Fiber Glass Reconstruction

This step is basically where all the hard work is concentrated. The solution I chose was to use fiberglass and build up the empty space between the bumper and the headlight.

  1. I first stared by sanding down the existing paint on the bumper and getting it to the primer.
  2. I then proceeded to cover the headlights with painters tape to protect them from the resin and other scratching sources. Important: the painter's tape proved to be insufficient even though I used two layers of it - the fiberglass resin penetrated it and stained my headlight a bit. I would recommend also using some aluminium foil or something similar to ensure that nothing leaks through.
  3. I then started to create cardboard templates too see what shape the fiberglass should be cut into - this doesn't need to be extremely precise as the fiberglass can be sanded and reshaped afterwards. It was just a starting point. I then built layer upon layer of resin - fiberglass until the structure looked sturdy enough - it will take around 2 or 3 layer of fiberglass. Some areas remained with two whereas the structures that had more curves into them required 3 layer just to fill the space towards the desired shape. After each layer, I left it to cure for a while before moving to the next.
  4. After all the fiberglass layers cured, I was left with a rough and sturdy structure that I started to sand in order to get to the perfect shape. This took a lot of time as I had to put the bumper back up each time to see if it fits better after sanding. Important: for the areas that were really close but now quite there, I went on and used only resin (without fiberglass sheets) just to fill in the space.
  5. When I was happy with the final shape, I went on and used bondo on it to bring it to an even smoother surface. This part here was also covered by the body shop that painted the bumper so don't insist too much on it.

Step 4: Fog Lights and Shrouds

This step was the most tedious and time consuming one. I would definitely do it differently next time.

The problem here was that I needed the covers and also the fog lights from an original 2015 model and even though the covers can be bought new (at a not so small price), the foglights themselves are really expensive and hard to source for me. So, I took the brave decision to reconstruct the covers from scratch. The initial step was to find some headlights that would fit the style and the ones I found were from an Audi A4 B7. Yep, I used Audi fog lamps.

The reason I chose these was that they came with this cover that I could use and create only a plate onto which I would attach it. This proved to be way easier said than actually done.

The first step was to fit the fog lamp body to the bumper - I did this with a few brackets made out of 1mm steel sheets. These brackets tied the lamp with the bumper and ensured that it's also aligned correctly (it doesn't beem weirdly). This step was a lot of trial and error but basically I cut down 1.5cm x 4cm sheets of steel that I first attached (using 3mm screws) to the fog lamps and then bent so I could connect them to wholes in the bumper.

After I was happy with how they fit onto the bumper, I started building the cover itself. This consisted of an aluminium sheet, through which I cut an oval hole to protrude the original Audi fog lamp cover, and then I sandwiched all this between layers of fiberglass. The initial shape of the aluminium piece was achieved using a cardboard template - and a lot of trial and error.

I will not elaborate on this step as I would not recommend doing it. Try getting the original Mazda covers and headlamps. One solution, if you can't get the lamps, is to get the covers and just blank out the hole for the lamp.

Important: note that if your car did not have foglights before, you will need to get a new left steering wheel stalk also. These are pretty cheap and can be changed in a matter of minutes. Bonus points for me: the Mazda connector for the fog light fit perfectly the Audi lamp.

Step 5: The Grill

This was an easier step as a nice original grill can be found pretty cheaply for this model year. The only problem is that the grill comes without the number plate covers and this can't be found anywhere. I left them blank for now, the number plate covers most of them, only the left and right pieces are missing.

Step 6: End Result and Prices

I will first tell you how much I spent so that I can justify my opinion on the end result. Please note that I live in Romania and some prices might differ considerably for your country.


  • 2015 Mazda MX5 bumper - 100 EURO
  • OEM grill - 40 EURO
  • Audi A4 fog lights + left stalk - 60 EURO

Materials and labor:

  • Fiberglass kit - 25 EURO
  • Paint job for the bumper - 100 EURO

In total, it's 325 EURO but I managed to sell my old bumper so it ends up being around 250 EURO which I believe it's really cheap considering the visual impact it has. Please note, that besides the painting of the bumper, I did all the work. The amount of hours I spent is probably around 30.