Exo Car “Ghettocet” Build Guide Part 6 – Addressing the Surface Rust

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The 1991 Mazda Miata from which I am building the exo car has led a rough life. This was especially evident when I finished the chassis cleaning in part 5; quite a bit of surface rust was exposed. Usually, I would wait to address the rust during the fabrication process while fitting the roll cage. But I am building this car in a unique environment exposed to the elements. As a result, I addressed the rust on the chassis before proceeding.

Surface Rust on the NA Miata

The surface rust is present throughout the chassis, with a large patch on the firewall and additional spots throughout. When addressed early, surface rust isn’t a big deal, and numerous products will treat, seal, and/or reform the areas. However, I wanted to remove as much rust as possible before spraying a rust neutralizer on the areas.

Surface rust present on the firewall of the NA Mazda Miata exo car.
A large portion of surface rust was exposed on the interior firewall when removing the liner and cleaning the chassis.
There are rust spots throughout the chassis of the NA Miata exo car donor chassis.
There are surface rust spots throughout the Miata chassis, such as those near the fuel tank.

Rust Removal

To remove the rust spots, I used several different-sized wire wheels and a drill. As you will see in the time lapse, I worked the areas with the wire wheels until they were smooth to the touch. During the removal, quite a bit of rust was released into the air, so I used a respirator and eye and ear protection. The removal process took around 2 hours in total.

Then, I used a leaf blower to remove any dust and debris the removal process deposited onto the chassis. Once clean, I applied rust-neutralizing spray paint to the entire chassis. I used a flat black from Ace Hardware to get the job done. The results turned out nicely.

The firewall after the rust removal and coating with rust neutralizer.
After sanding and applying the rust neutralizer to the firewall.
Rust neutralizer sprayed on the NA Miata chassis.
The entire top of the chassis is now coated in rust neutralizer.

Next

Is it finally time to plan and build the roll cage? Yes, but first, I must install a 220v outlet in the work area and set up the tube bender. The race season is also in full swing, so it will be around a week or two before I check in with additional exo car updates.

By Chris Simmons

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