Teardowns of the Tesla Cybertruck continue apace at Munro & Associates. This week, Sandy Munro’s automotive benchmarking firm has released a video on the Cybertruck’s rear cradle and electric drive module (EDM).
As seen in previous teardown videos, Munro sourced a tri-motor Cyberbeast for his company’s teardown efforts. Thus, this example has a tightly-packed electric drive module (EDM) in the rear. Along with the dual rear motors and supporting inverters, there’s also the rear steering module hanging on the rear cradle to boot.
This latest teardown on the Munro Live channel is hosted by Jordan Arocha, at Munro & Associates, along with lead engineer Kevin Harty. The duo step through a series of interesting tidbits in the rear cradle design, particularly concerning the suspension and steering layout.
The Non-Michael Mann Kind Of Heat
The layout is neat and organized, with the EDM hosting two motors with two plate coolers on top. The cooling circuit is also plumbed to feed the inverters, too. Jordan notes that cooling for the EDM is handled both with the gearbox oil and ethylene glycol.
Jordan also suggests Tesla may be netting some additional functionality by using the motors to generate heat when needed. “When you wanna heat the vehicle up, what previous Teslas would do is… they would stall out the motors, that would create heat within the unit,” says Jordan. “They would use the remote electric pumps to plumb oil into the plate cooler, to heat up the ethylene glycol, to ultimately heat up the battery.” He notes this can help eliminate the need for separate heaters to control battery temperatures. He suspects the Cybertruck may be relying on a similar system.
“Every exposed surface for the heat exchanger here is machined, which is interesting obviously and expensive,” says Kevin. It’s not entirely clear why this is done. By machining and then peening or swaging the parts, they may be creating a better thermal connection between parts of the inverter housing. This could have something to do with maximizing cooling for the insulated-gate bipolar transistors within the inverter. They deliver power from the battery to the motors and must be kept cool to avoid failure. “Keeping them cool is critical for EV performance,” says Kevin. “If you wanna go fast, and go fast for a long time, it’s imperative to keep them cool.”
Structural Concerns
The sway bar stands out right away on the rear cradle. “One thing we were talking about is the sway bar, and the fact that it might be a little bit ad-hoc or they might need a little additional locating retention for the sway bar itself,” says Kevin. We can see band clamps holding a rubber isolator around the swaybar to keep it from shifting left and right.
Kevin notes that more integrated methods are more typical for locating the sway bar in the correct position. “[It’s] something that I would say is not the most elegant execution in terms of the bushings,” says Jordan. “This is likely quite a manual operation to get these bushings on. That’s not great practice for a very high-volume application.”
Kevin notes that the rear cradle design is similar to front cradles in other contemporary vehicles. The rear upper control arms are mounted to the gigacasting on the vehicle, while the rear cradle can be dropped out without them. “They’re using the gigacasting that they bought and paid for to complement the structure of the cradle itself,” says Kevin. Jordan notes that when Tesla updated the Model Y in 2022, the front upper control arms were mounted directly to the gigacasting up front. The Cybertruck does the same thing in the rear.
Packaging is tight around the rear drive assembly, which Kevin notes could have an impact on maintenance down the road. “It might just be easier to dedeck the entire cradle if you’re replacing bushings, to do everything at once,” he says. It makes sense—dropping the rear cradle out of the vehicle would provide far more room for pressing out old bushings and installing new ones.
The rear cradle also mounts the rear steering rack. Jordan notes the unit carries Tesla branding cast into the body. “I don’t know if they’re building it in-house, but I would suspect it might be,” says Kevin. “It’s overall packaging size, [and] the way it’s laid out is definitely atypical and different from what we’ve seen in the past from suppliers like ZF.” The rear suspension layout features an upper control arm and lower control arm, with the steering link playing a role, too. It helps control toe in addition to actually steering the rear wheels, Jordan explains.
It’s also obvious the Cybertruck has massive disc brakes, which is no surprise given its hefty kerb weight of 6,843 pounds. The Cybertruck uses a large cast rotor, with some holes machined in to save weight where possible. It might seem insignificant in the grand scheme of things, but even shaving off a few grams can have a benefit when it comes to cutting unsprung weight.
There’s also a little threaded hole in the wheel hub which lines up with a hole in the rotor. It appears to be an assembly aid for keeping the rotor in place before the wheel is mounted. Jordan notes that many automakers use similar features, where a small bolt holds the rotor to the hub while on the assembly line. Many automakers will leave these in place on production vehicles. Tesla is either not installing these bolts on the production line, or removing these bolts after they’re no longer needed. Jordan suspects Tesla might be removing the bolts to save costs, while Kevin jokes that it may just have been dropped and lost at some point.
Moving on to the lower control arm, Kevin notes the welded assembly and the difficult packaging job involved. “I’m a little surprised they didn’t try to get the sway bar link bolted through on the control arm,” says Kevin. He suspects tight packaging constraints may have played a role. Instead, the sway bar link is mounted on a separate bracket welded to the control arm assembly.
Jordan also notes that the four-wheel steering creates a much wider range of wheel positions through compression and turning, complicating the packaging job at the rear. This could have influenced the placement of components like the sway bar link mount. “That structure’s got a finite amount of real estate in which it can reside, ” says Jordan. “With that four-wheel steer, you’re really starting to encroach here and limit where this control arm can package based on where that wheel envelope is.”
Also notable are the long spans between the inboard pivot point and outboard point on the control arms. This is a common design choice on vehicles designed for off-road use. “That’s gonna allow you allow a lot more travel on your suspension,” says Jordan. “By going further inboard with those, it’s gonna reduce the amount of acute angles that need to be present for both the bushings as well as the half shafts.” Reducing those sharp angles tends to put less strain on CV joints and bushings, and keeps everything happier for longer.
Kevin notes that the Ford Raptor and Ram TRX are based on production trucks, and have to compromise in this regard. The only way to get similar travel and height on those trucks is by using longer control arms, which means widening the truck. Hence, these vehicles have added flares to deal with the added width. In contrast, the Cybertruck has long-span control arms baked into the suspension design out of the box.
Jordan notes that an EV provides more flexibility in this regard to rear suspension design, versus a traditional ICE drivetrain. Furthermore, having the gearboxes for the dual rear motors offest to the rear helps as well. It makes it possible for the two output shafts from the drive unit to be tightly packaged close together. This allows for longer half-shafts that can run at less acute angles. “The further away from the driven point on the motor to the hub that you can get, the better off you are,” says Jordan.
Ultimately, there weren’t any grand discoveries that were found lurking in the rear cradle of the Cybertruck. Deeper investigation may reveal dark magicks in the inverters or motors themselves, or other tricks besides. In any case, when we know about it, you’ll hear about it here first at The Autopian.
Thx, it’s somebody’s last name.
No, seriously, fix “Sandy Murno”, this is triggering my OCD which is part of the reason I’d be all into an article like this.
Sounds like smart engineering since these will never be built in very high volume. 😛
Isn’t there two million in the order queue?
I believe those were just the $100 refundable reservations. I’m curious how that translates to actual sales.
Interesting stuff. (Sandy Murno, oops)
I really wish they wouldn’t use Tesla marketing-speak in a technical review. It is a casting, or cast structural member, not a “gigacasting”.
IDK, do you cringe every time someone says Thermos or Kleenex? New words enter our lexicon all the time. If anything, the ubiquitous use of a word lessens the power of the marketing
Thermos and Kleenex are each shorter than “insulated travel bottle” and “2-ply facial tissue,” as well as currently or at least previously representing the state of the art in their respective domain. The trademarks became such a standard that they were adopted into common usage, a process called genericization.
Giga- is a prefix meaning “billion” and has nothing at all to do with casting, and doesn’t really see common usage as a shorthand for “large.” It also implies, by virtue of creating this neologism, that there is something new or unique to this process such that it could only effectively be described by a new word or phrase. This is not the case with “gigacasting.” It’s just casting – which is already a pretty neat process! – but with Elon Musk trying to prepend vaguely technological language to make it seem new or novel. For folks like me, and I suspect Large Marge above, it has all the meaning of an 8-year-old writing “UltraCar” inside a cardboard box, but with less than no charm because it’s a grown man meaninglessly lifting language from wherever because he thinks it’s cool.
People could have just said “tissue”, which is actually in use, and neither Kleenex nor Thermos have any technical or novel value. There’s such a clear anti Tesla bias here, it’s wild. Try just relaxing. It helps. And “giga” absolutely gets used as shorthand for large.
The pendulum swings both ways. You seem to come across as a Musk (and I say Musk not Tesla) fanboy who is seemingly offended at anything that offends your lord. We can apricate some of the engineering in the CyberTruck, which even the name is stupid because Cyber means “relating to or characteristic of the culture of computers, information technology, and virtual reality.” and nothing about this truck means that.
It takes something to become iconic, with brand staying power for their proper names to enter the lexicon. Kleenex and Thermos were so good, iconic and dominated their respective markets that their names became synonymous with their products. It takes a great product (Maybe Coke) to make that happen. Musk calling his casting a “Giga Casting” doesn’t an icon make no matter how tight you mouth is placed on his wang.Maybe in 10 years but not just because he says so. Sorry
I like language and enjoy discussing, debating, and defending language. I’m also a proponent of clarity, especially in technical settings. “Gigacasting” needlessly obscures information about what the item is or how it was formed – casting.
Disliking or disagreeing about something, is not necessarily indicative of “bias.” I dislike licorice, but I don’t have a bias against it. I just don’t like it.
I chiefly dislike Tesla because they put too much emphasis on the touch screen, and because of its association with Elon Musk. If they backed away from those two ledges, I would have a much more favorable opinion. There’s no deep-seated bias against Tesla; I would like their products to improve and be successful; I don’t resent Tesla on the basis of its existence or go to any effort to put them down.
Except the CyberTruck, which is a fuck-ugly disaster of mismatched steel and poor planning.
Makes me think “Giga Chad” every single time I hear it, which I’m sure is exactly what they were aiming for.
I was just reflecting on how Tesla’s term entered the standard jargon before the idea even went into very large scale production.
Like it or not, other outlets and industry players have now used the term “gigacasting” more than Tesla ever did. It’s not Tesla’s word anymore.
As an engineer, I have no problem with this. They’re castings that are so large they become major structural members in the body. Thus, it’s nice to have a term denoting that usage.
I worked in casting for a major automaker, and gigacasting was BIG news all the way back in 2016. People in the industry knew it would be a gamechanger.
This has been so exhausting
I think it’s time for a cuppa tea and a GigaCookie from my CyberPantry.
I can speak on using the “band clamps” to hold on the stabilizer bar locators (I used to work for the company that makes them).
Ram also has done this in the past on their large diameter bars for the beefier trucks when the bar can’t be made with rings to crimp on. This can be because tooling or rings aren’t ready in time for production kickoff or rings can’t be applied based on how the bar needs to be made.
Now, on these specifically, based how small they are and it being Tesla, I’m going with the former, and there may be a crimped on ring coming in the future or they may be satisfied by the current performance and stick with it.
Thanks for sharing your insights! Always cool to hear from someone in the know.
Any time!
“maximizing cooling for the insulated-gate bipolar transistors within the inverter”
Future back yard wrenchers will have to be industrial electricians.
Great Scott! All that is missing is a time flux capacitor.
Just wrap the screwdriver with an extra layer of electrical tape and start poking
Just a different set of skills. I can only tune a carburetor and mechanical distributor into a condition of not running, like I did to my lawn mower last week…. oops.
But I can probably deconstruct the entire inverter with the tools in my basement. About $500-700 will get someone the same tools (a good quality bigass temp-controlled soldering station, reflow/preheat station, hot air rework station, tweezers of every shape and size, etc.)
Likewise, the same lawn mower I have thought about just converting to electric drive right on the spot using some random big floor cleaner/polisher motors I have. I don’t see this as necessarily any different than, say, someone who just had a garage of parts to cobble together a small block V8 build.
There has been an entire industry devoted to getting the tools and information to work on ICE vehicles into consumer hands for decades. That does not exist yet for EVs. And it might not because now manufacturers would prefer to sell services rather than products and have no interest in making them repairable outside of their service centers. Special tools, booby trapped procedures, DRM software, the works.
I’m guessing you have these skills and tools because your job is related? Also have you checked prices lately? Those tools sound like they cost considerably more than $500 or so. Unless there’s stuff at Harbor Freight that will work.
Yeah, for manufacturer-level support it will take time to diffuse. But I will say in contrast to your first paragraph that small EVs like e-bikes, go-karts, scooters, etc. are comparatively more open source or hackable (or buyable in pieces) and the same architectures apply as things get bigger, much like baby’s first moped carburetor has almost nothing in common with an 80s analog emissions laden 4-barrel except the first principle.
Honestly that’s really the toolpath I went down. I started fiddling with EVs first back in the Late Oughties, moved onto custom making motors and learning how inverters worked (and didn’t work, often explosively). Helped some friends and classmates do an EV conversion on two or three cars (a Porsche 914 for one, using the latest and greatest tech of 2009.5) I didn’t even get into ICE until ~2013 when I bought my first project wreck. My employment is because of those grassroots accrued skills, not the other way around.
I believe my price figure is reasonable for some “Harbor Freight Tier” electronics lab equipment. A good Chinesium multimeter is under $100, a soldering/hot air/chip poker combo station is around that much and uses knockoff name-brand tips and nozzles so you can buy the good ones separately. Test equipment is expensive in comparison but you can get away with a USB oscilloscope + multi channel logic analyzer/bus sniffer for $150-200. Adjustable bench power supplies that are worth using range from $50 to $500.
That’s all in my basement now, because I’m definitely not spending another order of magnitude of money for American/European shit for the cobbling and hammering together of parts I do 8)
Let’s put it this way – at this point in time in my life, if I am presented with a mystery electric car and told I had to get it running, there is a sequence of unfortunate events that looks like the following:
If it needs a new battery, I have some favors to call in and get a few hundred volts of lithium piled in the middle of my driveway. And they make high voltage alligator clips.
First I’d prod at it and capture data packets and do some playback attacks to get stuff to turn on.
If I can’t do that, I’m going to bypass the whatever module and jiggle the CANBUS/Ethernet/whatever directly.
If that’s encrypted, I’m ripping the endpoint out and replacing it with my own.
If the inverter is booby trapped to explode when I crack it open, I’m building my own inverter (or using one of dozens of aftermarket ones) and it’s going to be controlled by a really sweet set of 1960s machine control panel buttons and no touch screens. And it will have door handles.
This is why I’m more likely to build my own electric car (van) than buy one, let’s be real.
Break out the polish and get the junkyard one all shiny. No issue.
People said the same thing when unibodies, fuel injection and electric accessories came around. Different precautions is all. A good set of Klein insulated electricians tools, a voltmeter and some electricians gloves will become mandatory tools just like an OBDII scanner is now.