How To Refresh Your Race Car’s Interior in One Day | Project Endurance Race Miata

Update by Tom Suddard to the Mazda Miata project car
Feb 19, 2021

We’d been making great progress on the drivetrain and chassis of our LFX-swapped Miata, and were getting towards the fun parts of an engine swap–parts like wiring–which meant we had to divert our attention from the exterior of the car and focus on the interior. And, well, it wasn’t pretty. Before we got our hands on this particular Miata, we think it started its racing career as a Showroom Stock race car. What’s that mean for us? It means we inherited a mostly unmolested Miata dashboard mounted to the factory dash bar instead of one welded into the cage.

Over a few seasons of budget endurance racing, we’d decorated that factory dash with new holes, new switches, new wires and new damage. Oh, and we’d completely mutilated the Miata’s wiring harness, which had never been trimmed after the car’s transition from street car to race car. And did we ever tell you the story of the time we lit the car on fire while welding on the undercarriage?

In short, the interior wore the scars of a life spent on track, so we were ready to upgrade on several levels. We wanted a real steel roll cage element instead of the factory dash bar. We wanted a digital dash instead of the stock Miata gauge cluster. We wanted a switch panel with labels and working switches. And we wanted to erase our past wiring sins and install a new harness that would be reliable enough for endurance racing.

Thanks to Covid-19, we faced one big obstacle: time. Rather than meeting with our teammates a few nights a week for a few weeks in order to meticulously tackle this project, we’d transitioned to working on the Miata for marathon sessions bracketed by quarantine to keep everyone safe. That meant we couldn’t spend 100 hours completing a pro-quality race car interior paint job like we’d done for our LS-swapped 350Z. Instead, we rolled the Miata into the shop at Very Cool Parts for a one-day interior makeover. The results aren’t perfect, but we managed to turn a dumpster fire into a passable five-footer, which is plenty for amateur endurance racing.

The first step? Make room for progress, which meant unceremoniously ripping out the charred Kirkey seat (who knew they were so flammable?) plus the dash, wiring, and everything else. We knew we were finished when the smell of burning car no longer lingered. Did we mention it was a bad idea to light your race car on fire? Do as we say, not as we do, and always keep a fire extinguisher handy just in case.

We’d gotten down to our interior’s creamy sheet metal center, which actually turned out to be quite sharp. Before going any further, we grabbed a pair of angle grinders outfitted with a cutoff wheel and a flap disc, and spent 15 minutes removing as many sharp edges and extra brackets as we could. Again, our goal wasn’t perfection, just easy safety improvements with a side effect of minor weight reduction. After grinding, we scraped the molten plastic from our charred seat cover off the floor with a putty knife, then rolled the Miata outside.

Why outside? Because we were onto the second step of our interior makeover: prepping for paint. And because time was short, we settled on the quick and dirty method: a light spritzing of degreaser, followed by a much heavier spritzing of industrial pressure washer. Pressure washing won’t remove sound deadening or seam sealer, but it’s a quick and easy way to create a surface that’s just barely clean enough for paint to adhere to. Once the interior was mostly clean, we parked the car in the sun and went paint shopping. We made the exact same decision we’d made when painting our LS-swapped 350Z:

“We like coatings that are easy to clean, don’t hide dropped bolts and spilled fluids, and don’t distract on track with bright reflections from the interior. Past experience has taught us that battleship gray is a color that accomplishes all of these goals and has the added benefit of complimenting most exterior paint colors nicely.”

But before we could spray that fancy gray paint, we had a few other items on the interior makeover to-do list. First up? That OEM dash bar. We decided to replace it with a straight steel roll cage element, which should make the car safer while also providing a place to mount the steering column. Very Cool Parts’ owner Wayne Presley cut a piece of DOM tubing and welded it in place, making sure to match the original dash bar’s height so our steering column would stay at a comfortable angle. 

And even though we were in a hurry, we weren’t going to gloss over a few easy opportunities for upgrades. The first came when we removed the OEM steering column: It wasn’t just lightly charred and rusty, but it was heavy, too. Ididit makes a lightweight aluminum column that’s a bolt-in replacement for NA and NB Miatas, and at $350 we thought it seemed like a great deal for a claimed 16 pounds of weight savings over the factory column. We also ordered a new weld-on, quick-release steering hub ($120) since Ididit’s column comes with an oversized smooth shaft that’s designed to be trimmed to the driver’s preference.

Ididit’s column looks beautiful and feels rock solid, but we didn’t save as much weight here as we expected: According to our scale, the bare factory column only weighs 7 pounds with our old quick-release hub installed, while the Ididit column and hub total 3.4 pounds. To be fair, though, Ididit’s weight savings are based on a stock column and steering wheel compared to their lightweight column and wheel, so we would have saved more weight if we weren’t already starting with a race car with an aftermarket wheel. This column also offers other benefits aimed at street cars: As Ididit says, “Included in the box are accessories to retain the factory keyed ignition switch, factory self-canceling turn signal and multi-function switch on the column as well as retain the column shroud to keep a stock appearance.”

The column’s lower mounts bolted into the factory locations without any help, while the upper mounts are designed to bolt to the OEM dash bar. Instead, we welded two tabs onto our cage to locate the column.

While we had the welder out, we added a few more mounts for our next upgrade: a Racepak IQ3 Logger Dash. We threw the stock Miata gauge cluster in the trash can, and mounted this combination digital dash, lap timer, and logger in its place. Why’d we choose Racepak? Simple: We hadn’t used one before. Over the past few years we’ve installed digital dashes from AEM, Holley, AiM Sports, Stack and others, so we wanted to try out this $1790 option next.

Another big reason we chose the Racepak dash? It should integrate nicely with the company’s Smartwire Power Control Module. This $2045 magic box is a solid-state replacement for all of the Miata’s fuses and relays we’d removed, and will be the new starting point for us to rewire the car. We’ll cover the SmartWire’s installation and setup in detail in a future update, but for now we added mounts for the optional 8-switch Smartwire Keypad, too. ($642).

Once our brackets were welded in place on our new dash bar, we started painting. To save time, we did this the old-fashioned way: With a few scraps of cardboard and some careful rattle-canning, we were able to get an acceptable finish without too much overspray. This doesn’t look as good as a professional paint job, but it’s plenty good enough for this car and it only took an hour. We’ll call that a success.

Once the paint was dry, we cleaned the overspray from the windshield with a razor blade, mounted the Racepak goodies onto fresh paint, and stepped back to admire our progress: Our Miata’s interior was no longer a dark, nasty, charred wasteland. We’ll install fresh safety gear later, for now it’s time to get back to the LFX swap. We can already hear the unfinished wiring calling our name….

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