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Introducing The Black Rat, whose real name happens to be Schmidt, but as stable mate for The White Mouse*, the nick name seems appropriate.

TBR is/was a completely stock 2003 NB, with a matching hardtop (more on the colour later), fairly high mileage and two prior elderly owners.

I have long wanted to start from scratch with an Mx-5 and put it together with 'track only' in mind, and without holding back on irreversible modifications.



The purchase process was painful and I won't repeat it here - suffice to say it took some patience and a number of attempt to make contact with the owner over a period of months.

*Also not its real name.

I want to put a cage in this car, and I want to fit in it in a containment seat comfortably. I am not sure yet how successful I will be with this objective, but I began exploring the floor drop that is common to the spec Miata people. There are a few kits out there that claim 30-40mm of floor lowering.

My father-in-law is an expert metal whisperer and he visited me a recently. One thing lead to another, and before we knew it the carpet was up and we were measuring and scratching out dimensions for a new sheet metal floor pan. By the end of the visit, I had homework to finalise drawings and we made a plan to perform the surgery over the Christmas period.

First order of business was to strip the car and get it into shape for the work. The seats, soft top and a nice windblocker with integrated speakers went to new owners. I then had some fun with dry ice mixed with alcohol.



So clean, so quick.

These rough drawings are basically what we folded up in 2mm sheet. This was a little thicker than I had planned, but I am comfortable that we have added to the strength of the structure in spite of the changes we made.

Note that we made these square knowing that both sides (passenger side in particular) would require narrowing towards the front as the transmission tunnel widens. Starting with a square section, we had a certain amount of adjustment available when fitting.

This is me, sitting in the car without the seat (sitting on the floor), with my helmet on, with a little recline. The line you can see above my head is masking tape to simulate a straight line where I estimate the top of a bar between the front and rear cage sections might sit. No seat rail could make me any lower than this.

Test fit of my chosen seat - Velo Apex, made in Adelaide. This was sitting on planted mounts I think.

The new floor pans in the flesh

All set up ready to go. The car is sitting squarely on 4 axle stands - the wheels are just extra insurance.

The first tasks are to remove the factory underbody bracing, exhaust heat shield, fuel lines and brake line. None of the items will fit after the floor pan changes.



What it looks like just after the point of no return...

Good luck with it mate, can’t wait to see the results

You're not waisting any time there.

Flintstones car.

Red_Bullet wrote:You're not waisting any time there.

bruce wrote:Flintstones car.

Daffy wrote:Good luck with it mate, can’t wait to see the results

thanks fellows. I am having a very relaxing Christmas.

First side tacked in









We attacked the passenger side first. I can see now why the north Americans have so much trouble fitting seats. The tunnel bulges quite a bit on this side.

The driver's side is more involved because it requires removal and relocation of brake and fuel lines, but it too went in the following day

I had planned to use some fabricated rails to stiffen the floor and tie the body and new floor pans together. This would have been quite bulky and would have further eaten into limited ground clearance. Instead, somme 75x50mm flat bar was pressed into service



it is all very stiff now

Yreckon you will keep up with Keith and Rons 10 grand shitbox this time around?