Dec 6, 2023
Peterborough, Ontario's ARC Motors will electrify your old, CO2-spewing clunker into a modern, emissions-free sophisticate.
It would appear there’s a whole bunch of classic car aficionados out there who want to relive — or experience for the first time — the charm of yesteryear without the trials and tribulations that antiquity always seems to engender. In plainer words, they want the style without the hassle. Or at least that’s what Sloane Paul, CEO and co-founder of Arc Motors thinks.
So, let’s just say you have a beautiful Seaglass blue 1974 Ford Bronco so immaculately restored — by Bronco specialists Legacy Speed & Body in Calgary, Alberta — you’d swear it just rolled of the production line in Wayne, Michigan (where all Broncos were originally manufactured). The body is perfect, the frame straight and the interior bestowed of a refurbishing that would do Lamborghini proud.
But then, you’re stuck with that engine. Never the most stellar example of internal combustion, Ford’s base 200-ci inline six was a little dated even for its day, a pokey little thing with a few foibles — overheating, stalling, etc. — that might, even when properly fettled, leave you stranded. The powertrain was, not to put too fine a point on it, agricultural. Throw in a 50-year-old wiring loom and, say, a transmission that might not be as reliable as you might want and, that “ease of operation” that Paul — herself a diehard classic-car enthusiast — envisages starts to look pretty appealing.
Rather than trying to turn what was always cranky into something passably modern, Paul’s vision for these “just hop in and drive” restorations is a wholesale swap of everything that powers the old Bronco. Pistons are replaced with stators, carburetors with inverters, and the powertrain that was once fuelled by gasoline now looks to a lithium-ion battery for its motivations.
Yes, this ‘74 Bronco is electric!
Don’t fret too much, the spirit of hot-rodding is still very much alive at Arc Motors. So, just as many resto-mods feature an updated engine — Ford’s 5.0-litre Coyote crate motor is a common replacement — swapped into the engine bay, the FrankenBronco sources much of its powertrain from the modern electrics inside Tesla’s Model S.
That’s where Arc’s head of engineering, Tom Chep, sources the batteries for his electrified Bronco. Of course, simply swapping in a flat-bottomed Tesla power pack is completely out of the question. Tesla battery packs are designed to be built into the floorplan of a traditional “skateboard” platform. A Bronco, of course, is built on frame rails, not a unibody. In other words, there’s not a flat surface to be found. Besides, a brand-new Tesla battery would eat up about half of the estimated USD$75,000 Arc estimates it will cost to electrify any restomod.
The solution to both problems? Chep sources used Tesla battery modules from 057 Technology, a wrecker that specializes in recovering battery components from wrecked Teslas — then he builds his own battery. This is by far the most complicated and time-consuming portion of the ARC’s battery-powered Bronco build. Electric vehicle batteries — especially Tesla’s — have extremely sophisticated cooling and monitoring systems. Since, he’s starting with bare modules, Chep has to build both systems himself, manufacturing the necessary cooling circuits and then wiring the cells to motherboard so that the FrankenBronco’s battery cells operate as efficiently as they do in a Tesla.
When he’s done, the old Ford sports 15 of the 16 battery modules that powered the original Model S. The result is a seemingly very modern — as in competitive with current Model 3s, Hyundai’s Ioniq 5 and the like — 75 kilowatt-hours of lithium ion. Range, because the Bronco is basically a brick on wheels, isn’t quite as competitive, Chep estimating his much-modified ’74 is good for about 320 kilometres on a full charge. Of course, the chances of anyone driving more than 320 klicks in a day in a 50-year-old Bronco — especially one so pristinely restored — are probably fairly minimal. And I suspect — as blasphemous as this will sound to the diehard Bronco fans out there — there’s even less chance that they’ll get caught way out in the boonies with no access to charging with this particularly pristine restoration.
That’s a good thing because this current iteration of Arc’s conversion has its charging limitations. Because the electric motor — more on that in a minute — operates on a relatively low 120 volts, DC Fast Charging is not available under any circumstances. The quickest charging available is a 6.0-kilowatt Level 2 affair which means the Bronco’s — again, impressively large — battery takes about 12 hours to charge. And yes, if you know your Teslas, you’re already wondering how Chep’s little monster works on 120 volts when the Model S from which he liberated all those lithium-ions operates at 400 V.
Well, Chep gets around this by first connecting five of the Tesla 24-volt modules in series. Three sets are then connected in parallel, and presto, the Bronco boasts almost as many kilowatt-hours as the original Tesla, but its output voltage now matches the 120 V motor. Like I said, the spirit of the eternal hot-rodder remains intact, only directed at battery discharge rates rather than compression ratios.
That reduced voltage doesn’t mean the revitalized Bronco is underpowered — indeed, the opposite. The two HyPer 9 Hybrid motors — which a unique permanent magnet-assisted synchronous design — produces 130 horsepower and 173 pound-feet of torque for a total of 260 horsepower and 346 pound-feet of torque, virtually doubling the 120 horses the original straight six boasted and far more than its 190 lb-ft of torque. Even the original optional engine — Ford’s venerable 302 cubic-inch V8 — claimed but 125 hp and 243 torques. Needless to say, the newly electrified Bronco is decidedly healthier than the original. That said, Chep is already looking to upgrade the engines, looking for not only more power but also the higher operating voltage that would allow DC Fast Charging.
The rewiring of Tesla batteries may be impressive, but it’s the packaging of all this electrification that is truly brilliant. Though I’ll make it sound a lot easier than it was to engineer, essentially the twin electric motors and single-speed transmission now reside in the transmission tunnel where C4 automatic once resided. That means, if you know your Broncos at all, that both front and rear driveshafts, while modified — Chep mentions the addition of CV joints to deal with greater angularity — are in roughly the same orientation as the original ’74. It also means that both front and rear differentials — which he says are just about the only mechanical bits that survive unmolested — are essentially original units.
With engine and transmission absent from the engine bay, there’s now place for those Tesla battery modules that once resided in a Model S’ floorpan. Now encased in a hand-built solid steel box — future encasements will be CAD/CAMed from aluminum — the battery pack takes up a sizeable portion of the area once occupied by the old straight six. Oh, there’s room for the upgraded Wilwood brake booster that helps the standard Bronco brakes contain all that torque. But what makes this all the more brilliant, if you’ve been following along at all, is that this same basic format is transferrable to pretty much any classic bit of iron. As long as the transplant recipient followed the classic front-engined, rear- or all-wheel-drive format, Arc Motors should be able to electrify it with only the specific packaging and mounting points differing from the basic format Chep is well on his way to perfecting. According to both Chep and Paul, one of the projects being considered going forward is a monstrous Power Wagon.
Oh, and one last thing about this quasi-universal adaptation; because everything is engineered to fit where previous components resided without modification, Chep says that this 50-year-old Bronco could easily be returned to its original ICE ways by simply stripping out the electrical bits. Though, if ARC’s electrification really does prove as trouble-free as promised, it’s hard to imagine anyone wanting to return to piston power.
Author’s note: The brainchild of brother-sister duo Sloane Paul and Tom Chep, Arc Motors is located in that (sarcasm alert!) hotbed of automotive development, Peterborough, Ontario. That said, local government and business have rallied around Arc, Community Futures Peterborough and the Peterborough Airport kicking in funding, mentorship, and other assistance. From humbler beginnings have great innovators been forged.
Arc is looking for new challenges, so people looking to electrically restomod their classic car or truck is encouraged to contact them at ARCmotors.com. One word of advice: the decision to electrify is probably best made before you restore your pride and joy’s exterior. According to Chep, the most intimidating part of the Bronco conversion was not the technology hurdles, but the trepidation of installing all the large, heavy (and some decidedly square and pointy) bits into Legacy Speed & Body’s seemingly 100-point restoration. Just one little ding from the thousand-pound battery would have meant a complete do-over. Electrify first, restore after is Chep’s new mantra.