Miata Rebuild

Evaluation

I bought the car in April of 2019 knowing that the front end would require a lot of reconstruction . I expected this to include the cooling system, subframe, body work, and air conditioning. The driver’s seatbelt and airbag had also been deployed. What I didn’t anticipate was some wiring and ECU work.

Subframe and Parts Acquisition

The first thing I tackled was the subframe, which was largely missing from the car. Pictured is the crumpled subframe, as well as where it was attached to the chassis.

I then painted the cut areas with a weldable primer and aligned the new subframe with the frame rails and fender mounting locations. Using a resistance spot welder, I mimicked the factory welds I had just cut, twenty-two in total.

I loaded the back of my brother’s station wagon (which I did some paint work on the year before) with parts from a dealer in Chicago. Though 400 miles away, the prices made it worth the drive from MN.

Cooling and Electrical

The new radiator, reservoir, airbox, and fan went in without a hitch. I was able to start the car on the first try. I had to remove the majority of the interior to access the seatbelt and airbag controller, but they were both straightforward to replace.

What proved more troubling was an issue with the mass airflow sensor (MAF). I reused the original unit because it seemed to be in working order, but I was getting a value of 0 which is not normal. I checked all the fuses and power to the sensor. I was getting the right voltage at the sensor, and it was spitting out a signal voltage, but still no reading at the ECU

It turned out that two wires had been sliced in the crash, one the signal wire and the other power. I was still seeing a voltage at the sensor because of the integrated air temperature sensor, which I was unaware of before unwrapping the harness to find the sliced wires.

Paint

I had to paint the new hood, left fender, and bumper. The paint on this car is a tri coat pearl, meaning that there’s a layer of primer, several layers of metallic, a tinted clear coat, and a sealer coat. If you vary the number of layers of metallic and tinted clear you’ll end up with a very different color in the end. This makes it extremely difficult to match.

I used test pieces with varying layers of tinted clear and metallic to determine the best match, but the first time I painted it it still came out wrong. I had to sand back all my work and start from scratch. The second time I painted the color matched really well. It has a smooth, pearly surface. The results were better than some body shops I’ve seen do similar work.

Results

The car drives and looks like it’s new. Here I am standing next to it, as well as giving my grandpa a ride around town. His favorite color is red.

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