Atom Imposter: Building an Ariel Atom Replica From Scratch


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Think that’s an Ariel Atom? Look closer. It’s actually a custom creation hand-built by Jon Winterhalter in his normal suburban garage. While the English mid-engined sports car was the inspiration for Jon’s near-replica, he says he’s never seen an Atom in the flesh.

That little inconvenience didn’t stop him, though. In this Internet age, Atom owners proud of their $50,000 purchases have posted enough high-resolution photos for Jon to create his own scale drawings and build an almost perfect replica.

This amazing car is not, however, the result of beginner’s luck. Jon built a Lotus 7-like Locost a few years ago and entered it in the Grassroots Motorsports $2005 Challenge. It was even featured in a few other mainstream car magazines.

With that challenge behind him, Jon wanted something more impressive and a little more difficult for his next project. One of those high-resolution Atom pictures gave him the idea for this build.

“I liked the distinctive look of the curved tubes and wanted a bigger challenge than building another Seven-type car,” Jon explains. “But honestly, after building my first car I was not afraid, not surprised by anything. I knew I could build this one.”

After fabricating his own tube-bending device, Jon cut, bent and welded a stack of long steel tubes to form the car’s complex frame and suspension.

After fabricating his own tube-bending device, Jon cut, bent and welded a stack of long steel tubes to form the car’s complex frame and suspension.

Jon’s only reference points to the genuine Atom were its published wheelbase and track width. With those figures in mind, he started downloading and analyzing more than 150 photos. How did he figure out the measurements? “It helps that a standard U.S. license plate is 6x12 inches,” Jon explains. Not everything was easily determined from the pictures, though, as he had to make an educated guess at the diameter of the main frame tubes.

He drew up some plans on paper, but he didn’t make a complete set of drawings for the project: “I designed most of the car—other than the suspension boxes and chassis rails—on the fly. I could have done it in CAD, but it could have taken a year for me to learn the program and work out all of the details, and I might have gotten bored with the project.”

Jon’s success can be attributed to his day job as a civil engineer—he knows when to depend on his own judgment and when to copy established designs. Frequently attending local competitive events provided plenty of inspiration.

“I calculated stresses on a few items,” he explains, “but for the most part I copy other designs. I go to a lot of hillclimbs and races and take a lot of pictures and measurements of things. As long as I’m using the same size parts as cars that weigh about the same, I’m okay.”

A banged-up Honda Civic donated its low-mileage D17A2 engine and a variety of other parts to the build.

A banged-up Honda Civic donated its low-mileage D17A2 engine and a variety of other parts to the build.

Once he had a design in hand—well, in his head—Jon began the search for a suitable donor car. The real Atom is powered by a twin-cam Honda K-series engine, but Jon’s search didn’t produce any reasonably priced donors. He couldn’t find an affordable Civic Si, Acura RSX or TSX that could provide the needed engine, transmission, wiring harness and miscellaneous plumbing. In the end, while searching the junkyard for parts for another project, he stumbled across a donor that he deemed good enough.

“I went with a 2001 Honda Civic with a D17A2 motor,” he says. “I decided on it mostly because there was nothing else as cheap out there when I was looking.”

The 127-horsepower SOHC engine was not his holy grail. However, it would be enough to vigorously propel 1200 pounds, his target weight for the project. Plus, the $800 package included the badly wrecked shell—only 29,000 miles showed on the odometer—plus all the parts needed to put his “Atom” on the road. For maximum reliability and streetability, Jon retained the factory harness, ECU, fuel pump and sending unit. The drivetrain is basically stock, but moved behind the seats.

Nucleus

The Honda’s drivetrain and subframe are situated behind the driver.

The Honda’s drivetrain and subframe are situated behind the driver.

Not one to use outside vendors, Jon did all of the fabricating himself. Well, he had to source out one thing: cutting the state-required laminated windshield.

The chassis started out as a stack of 24-foot-long steel tubes. Each one had to be cut down, bent, notched and welded together. Most of the frame was MIG welded, but the suspension arms and many of the aluminum parts were joined with the slower but more precise TIG welder. Jon figures that 95 percent of the car is made of DOM steel tubes. The materials cost maybe $1000, he adds.

The brakes were his biggest expense at $1300. However, he went with brand-new Wilwoods—including their four-piston calipers up front plus a dual master cylinder. A Chinese-made aluminum radiator from eBay provides cooling. The tires and wheels cost $1000. Most of the other parts, such as the shocks, were bought used at a low price.

During construction, the most difficult portion of the project was fabricating the main tubes and their triangulation braces. Each of the braces were cut to fit rather than designed beforehand. The curved shape of the main tubes was tricky, as Jon couldn’t find a single local shop that had the right kind of tubing bender. So, with his usual pragmatic attitude, Jon decided to make his own.

“The cheapest tubing bender out there is around $1000, but I looked at some pictures and knew I could build one,” he matter-of-factly states. “That was the big challenge early on. Everything else was relatively easy from then.”

He also had to build a rotisserie as well as a paint booth. As Jon explains, those are the costs of building a car from thin air in a suburban garage.

While the structure was coming together, Jon couldn’t forget about mimicking the look of the original Atom. One important touch was the central hoop/superstructure. As Jon explains, this feature is not a roll bar. The central hoop is just there to look good.

Style has its price, though, as the structure is made from 0.095-inch wall tubing and adds about 100 pounds of unnecessary weight. However, there’s no penalty when it comes to the cool industrial paint scheme, with its flat black frame tubes and brushed aluminum.

“I brushed the aluminum with a 220-grit finish and waxed it,” he explains, “so no polish, just Windex and a paper towel.”

Subatomic

Jon continued his fabricating streak into the suspension construction. Even the uprights were homemade, although Jon admits this was mostly for aesthetic reasons. “I could have used some off-the-shelf parts, but I wanted them to look good.”

But that doesn’t mean they aren’t functional, too. As Jon explains, they received more design work than anything else on the whole car. “It was time-consuming to design them,” he admits. “I had to take into account kingpin inclination, offset, scrub—you basically have to decide on a wheel and tire size way in advance.” The car features fairly conventional 15x7-inch wheels at all four corners, although Jon opted to use a staggered tire setup for additional grip at the rear. 

The rest of the suspension is just as well planned, as Jon used a spreadsheet to arrive at baseline spring rates. Always preparing for the future, he made sure that the suspension pivots were adjustable. “Each corner has a three-position bellcrank that lets me change the motion ratio up to 1:1,” he explains. This feature allows for nearly infinite adjustability when combined with spring rate changes. 

Also like its inspiration, Jon’s car doesn’t have any anti-roll bars. It sounds unusual, but he says it works.

Radioactivity

Jon’s “Atom” is the kind of project that many of us wish we could build. Some of us start projects this ambitious, but very few of us have the time, enthusiasm and budget discipline required to actually finish. Some of that may be due to age or inexperience, but raw determination helped in this case—well, that and a comfortable garage.

“I forced myself to go out in the garage nearly every day,” he says. “I have a TV out there and watched a lot of English football while working.”

While the fabrication and construction challenges were difficult, they were expected. What Jon didn’t anticipate was the trouble it took to get the car registered. His home state of Pennsylvania has a fairly straightforward process for registering specially constructed vehicles that involves private inspectors who determine roadworthiness. 

In this case, unfortunately, the paperwork got hung up in bureaucratic quicksand. The state even sent a government-employed inspector to Jon’s garage. Instead of the expected six weeks, the approval process took three and a half months. To get the state’s approval, Jon had to make a few changes, including adding bumpers and a full engine cover. 

Jon’s “Atom” is the kind of project that many of us wish we could build. Some of us start projects this ambitious, but very few of us have the time, enthusiasm and budget discipline required to actually finish. Some of that may be due to age or inexperience, but raw determination helped in this case—well, that and a comfortable garage.

“I forced myself to go out in the garage nearly every day,” he says. “I have a TV out there and watched a lot of English football while working.”

While the fabrication and construction challenges were difficult, they were expected. What Jon didn’t anticipate was the trouble it took to get the car registered. His home state of Pennsylvania has a fairly straightforward process for registering specially constructed vehicles that involves private inspectors who determine roadworthiness.

In this case, unfortunately, the paperwork got hung up in bureaucratic quicksand. The state even sent a government-employed inspector to Jon’s garage. Instead of the expected six weeks, the approval process took three and a half months. To get the state’s approval, Jon had to make a few changes, including adding bumpers and a full engine cover.

Isotopes

The cockpit doesn’t offer much in the way of weather protection—unless you count the windshield.

The cockpit doesn’t offer much in the way of weather protection—unless you count the windshield.

After more than 2100 hours of work and about $8000 in cash, Jon is the proud owner of a hand-built, one-off creation—something that makes the official Ariel Atom seem mass-produced.

Thanks to the single-cam engine and a few other small differences, Jon’s car even undercuts the original on the scales. His weighs close to 1260 pounds, nearly a hundred less than the genuine article. It’s also speedy enough. “It’s a much faster car than I can drive,” Jon admits. “There are no signs of snap oversteer.”

Jon’s “Atom” carries 45 percent of its weight on the front axle, and the many available chassis adjustments provide plenty of room for tweaking. The mid-mounted engine gives it docile manners and unbelievable grip. Frequent autocross events have provided a great place for doing back-to-back testing, he adds.

The car can’t defy physics, however, and has already been stress tested in an off-road excursion involving wet leaves and a mountain pass. Luckily everything worked as designed, and the control arms buckled before damaging the frame. 

The repair required nothing more than a little cutting and welding to replace the damaged parts. “I cut some new tubes and there are a few dents in the aluminum, but everything worked just fine and the car didn’t suffer any permanent damage.”

Jon says that possibly his only regret was not holding out for a twin-cam donor car. While he’s happy with the performance, like most of us, he reckons he could always use a little more power.

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