Exo Car “Ghettocet” Build Guide: Part 2 – Trimming the Fat


Exo cars come in all shapes and sizes. This one is an extreme example of what is possible on a limited budget. As such, in part 2, it’s time to get out the cutting tools and get the car chassis down to as low a weight as possible.

Starting Measurements

Once again, I took the time to measure the weights before and after. In part 1, the starting weight was 1966 lbs. This is a little light from the factory curb weight of 2160 lbs. Mainly because the car came to me with the front end already chopped off. And after removing anything that bolts to the car, part 1 ending weight came in at1579 lbs.

That’s a long way to say that the starting weight for part 2 is 1579 lbs. Let’s see how light we can go.

Prep, Safety, and Tools

Cutting the excess body panels, like the rear quarters from the car is one of the more dangerous aspects of an exo car build. The cutting itself will create metal dust, sparks and embers, and leave behind more than a few sharp edges. And since this is a guide, I’m going to jump into safety for a bit. The following are my main safety concerns and how they are addressed.

Concern number 1 is the fuel in the tank. Before any cutting starts on the chassis the fuel tank should be drained and/or removed. I opted to drain the tank as I am not quite ready to separate the chassis from the subframe. In hindsight, I should have drained the tank via the fuel pump when the wiring harness was still intact. Since I did not, I went the long way, removed the fuel pump and pumped the tank out manually.

Second is the tools themselves. I used a reciprocating saw (aka Sawzall) and a 4 in angle grinder with cutting wheel throughout this process. These tools are dangerous by nature and do not stop immediately when power is depressed. So being mindful of where the cutting end and your body parts are at all times is a must. Slow and steady works wonders for safety with cutting tools.

Finally, and the main reason I took this aside is eye, ear, and lung protection. I have worked in a lot of hazardous environments and the amount of people that don’t protect themselves is insane. Unfortunately, you usually don’t show signs of exposure damage until the damage is done. For metal cutting I use:

  • P100 OV rated respirator for my lungs.
  • Over the ear protective earmuffs for hearing.
  • Safety glasses with additional face shield for the eyes.

It’s not overkill and breathing in metal dust is not conducive to long term health. And have you ever been around a group of ‘macho racers’ before. You can easily tell who skips ear protection. Eye protection I find to be self-correcting as eye damage is instantaneous in most cases.

Trimming the Fat

Below is a timelapse of the process but in short, I worked around the rear of the car cutting the center top support out first and then the rear quarters. This was my first time doing this on a Miata and was pretty straight forward once I figured out how everything connected. Also, I took my time with the cuts as it will always be easier to remove a little more than to have to repair potential frame damage when removing too much.

Results and Next Steps

The results are pretty spectacular. The weight now sits at 1397 and I still have about 100 lbs left to remove. For the next step I am either going to clean up the cuts and edges, remove the sound deadening and prep for the cage. Or I will go ahead and separate the chassis from the subframe. Either way there is much more to come and more pics below.

Speedway motors corner balancing scales showing the weight of the exo car after round 2 of weight reduction.
The Mazda Miata is down to 1397 lbs. after part 2. Can it still be called a Miata though?
The aftermath of cutting the rear quarters and arches out of the miata. Shaping up to be a super light exo car.
The aftermath of part 2. The Miata is looking a little sparse at the moment.
Almost 200 lbs of unnecessary body work for the exo car build.
Not as impressive as the pile of parts from part one but still almost 200 lbs. off the car.

By Chris Simmons

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