Home » The Tesla Cybertruck Has A Mystery Feature Inside Its Wheel. Help Us Figure Out What It Is

The Tesla Cybertruck Has A Mystery Feature Inside Its Wheel. Help Us Figure Out What It Is

Tesla Cybertruck Mystery Nub Ts
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The Tesla Cybertruck is slowly revealing its secrets as various engineering groups are tearing it down and looking inside. Munro & Associates is well known in this industry and is in the early stages of its own teardown effort. Much of it will involve costing out parts from a production standpoint and other dry work, but it’s revealing some interesting curiosities about the truck, too.

As shared on the Munro Live YouTube channel, the team has picked up some interesting findings with the vehicle just by throwing it on a hoist and peering beneath. The most interesting finding confounded the Munro team somewhat, and it’s been much the same for those of us in The Autopian office.

Vidframe Min Top
Vidframe Min Bottom

It all concerns a little aluminum nubbin mounted to each front suspension assembly, just inside the wheel. What’s it for?

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Clear as Mud

“This is a separate piece of aluminum bolted to the front end of that knuckle … that upon first glance doesn’t appear as though this was assumed or protected for in the initial design,” says Jordan Arocha, director at Munro & Associates. We’re told the metal piece is attached with two bolts to the front of the knuckle. It likely required machining threaded holes into the knuckle for mounting.

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It’s a curious piece. The fact that it’s a bolt-on, rather than an integral part of the knuckle, suggests two things. Either it was a late addition to the suspension design, or it’s intended to be swappable to suit different size wheel packages. But neither detail answers what it’s there for in the first place.

Image1166
The nubbin from a wider angle.

The leading theory is that it’s for crash safety. In particular, Arocha suggests it’s to help the Cybertruck pass the Small Overlap Rigid Barrier (SORB) test. This test involves the vehicle hitting a rigid barrier that protrudes just 25% of the vehicle’s width in front. This type of crash presents highly asymmetrical loads on the vehicle.

“In a SORB event, the wheels are not always your friends,” explains Arocha. “They’re a very hard object believe it or not.”  In a side overlap crash, only a small amount of the bodywork is responsible for handling all the kinetic energy of the collision. Thus, it’s important to make sure that energy is absorbed and distributed properly.

Sorb

Arocha notes that as the vehicle goes through a SORB-style collision, the wheel and suspension components all begin to compress together in a situation referred to as “stack up”. When this happens, the wheel must be dealt with properly to avoid the crash pushing it into the cabin. Cabin intrusion is highly undesirable for passenger safety, so mitigating the possibility wherever possible makes sense. Typical strategies involve suspension designs that crack the wheel, deflate the tires, or allow it to be pushed outward and away in a crash.

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That’s what Arocha thinks this part is doing. By reducing the space between the knuckle and the wheel, he believes the part “is probably to help fracture the wheel.” Furthermore, he suspects it could also be to help the suspension components get loaded up more quickly in a crash event by reducing that same distance. This could help get the failure sequence of the suspension components right to avoid cabin intrusion by the wheel or other parts. He notes, however, that it’s hard to be sure without seeing such a crash test in action.

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Sandy Munro, CEO of Munro & Associates, is on the same page, but notes a similar uncertainty. His idea is that the bolts holding the part to the knuckle could create a strategic weakness. He speculates this could free the ball joint and send the wheel moving free in a crash.  That way, he notes, “it’s not gonna be heading into the cab.” Also notable is a blue inspection mark, seen on the parts on both sides of the vehicle. “I think there’s more to this ’cause it’s even got a little mark on it… I don’t know what the heck that’s for, says Munro.

The crash safety theory perhaps makes the most sense, but nobody seems 100% certain. I decided to go right to the source, asking Cybertruck Lead Engineer Wes Morill what the deal was. Sadly, Morrill didn’t get back to me, all the more disappointing because it cost me $20 to message him on Twitter thanks to the whole Premium nonsense. Worth a shot but I kind of regret trying. That’s a whole pizza! Or four frozen pizzas! Bah.

Under Ct

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Anyway, with Morrill staying quiet, we can speculate about another potential purpose. One contrary idea is that the device could be an aid to wheel balance when off-roading in the sloppy stuff. By closing the gap to the wheel, it could help remove dirt, mud, or sand from the inside of the rim. These can readily throw off your wheel balance and create horrible vibrations. If you’ve ever been for a drive on a moist beach and then felt your steering wheel shake on the way home, you’ll know what I mean.

At the same time, this explanation seems less likely. It’s an edge-case problem that only occurs in circumstances where the sand or mud is particularly sticky and tough. It’s also nothing that can’t be solved with the quick application of a hose or power washer. Given Tesla didn’t even realize the Cybertruck’s wheel covers were going to shred tires, it’s hard to imagine them being so conscientious to design for this edge case.

A similar part exists on the 2020 Land Rover Defender, though it’s not something you’ll see on every off-roader out there. If you head over to AutoBlog, they’ve got lovely pictures courtesy of Dan Edmunds. He suggests the part is a mud scraper, but that’s his analysis, rather than a statement of fact from the engineering team behind the vehicle. Notably, it’s also a bolt-on part that is reportedly only fitted to vehicles optioned with 20″ wheels. Models with smaller wheels don’t get the part.

This video gives us a look at the brakes of a modern Land Rover Defender.

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We can see the Defender has the nubbin, but only on the front wheels. Is this because it’s a SORB countermeasure, or because muddy unbalanced wheels are only considered a problem for the steering axle? I’ve reached out to Land Rover for comment on the purpose of this nubbin. 

It does at least seem the intention is to reduce the gap to the wheel in the Land Rover’s case. For vehicles with multiple wheel sizes, it could make some sense. Models with smaller wheels would have a close enough gap between the brake caliper and the wheel that mud buildup wouldn’t be a problem. With bigger, more open wheels, though, a scraper could potentially have some utility. They’re sometimes used on rally cars, too, to avoid wheels getting unbalanced on long dirt stages.

A DIY mud scraper fabricated for a rally car.

Other Details

Another interesting detail is the plastic cover on the bottom of the front suspension arms. Arocha notes this is probably an aero part. It would help smooth the flow under the vehicle, contributing positively to the maximum range of the Cybertruck on a single charge. However, it also looks like a perfect little tub for mud to build up inside. Arocha also notes it uses three whole fasteners to mount to the suspension, which is excessive when other cheaper snap-on mounting technologies exist.

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The team also spotted a spare high-voltage connector on the battery pack. Speculation suggests it could be for an additional charging method, or for powering some kind of in-bed accessory. The charging explanation is a curious one given the connector is a small one that would not be able to carry huge amounts of current. Blanked-off low-voltage connectors were also found under the body. Arocha notes that this would typically be a provision for features that aren’t installed on the particular vehicle.

However, Munro notes that the company is tearing down a fully loaded Cybertruck. Thus, the connectors could be for some other model with more features coming down the line. Alternatively, they may be for plugging in a calibration device or other tool during production.

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Also interesting to note are tooling marks visible on the rear cradle castings. However, these marks aren’t indicative of work done to the castings themselves. Instead, it suggests that the dies that make the castings may have been modified from their original geometry.

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This may have been done to improve metal flow through the die, or in pursuit of weight savings, the team speculates. Tool marks on the die are then transferred to any castings it produces. These tool marks can be removed if desired, but this is largely unnecessary for a non-cosmetic part. The regularity of the tool marks suggests modifications were done by CNC machinery.

Image1238

The Mystery Remains

For now, we still don’t have a definitive answer as to the purpose of that weird suspension nubbin. The Land Rover world seems certain that the part on the Defender is a mud scraper, while Munro’s team makes a great argument for the SORB mitigation theory.

In a neat update, we also have a couple of extra images sent in by an anonymous source. One is a drawing of the Cybertruck’s front suspension, clearly showing the nubbin in place. The other shows us the nubbin looking in through the spokes of the Cybertruck’s wheel. With the nubbin in place, it looks like there’s still a gap of half an inch or so to the rim. We’ve also seen an image of a pre-production Cybertruck shared by Fuzz that suggests the extended nubbin used to be a part of the casting, not bolted on.

Screen Shot 2024 03 25 At 5.29.26 Pm
Making these and bolting them on is costing Tesla money, so they’re there for a reason.
434180696 1086599942571153 509777904147198746 N
There’s the nubbin. Note that it would only contact the very inner part of the rim in a crash.

I could go either way; both explanations make great sense from an engineering standpoint. My money’s more on the SORB theory, though. Tesla simply isn’t known for taking a belt-and-braces approach to off-road driving; some of its vehicles do badly enough in deep puddles.

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If you’ve got some more insight, throw it below. In the meantime, I’m going to keep my ear to the ground and try and get the real story from the engineers that made the call.

Image credits: Munro Live via YouTube Screenshot, IIHS, Quickclipsmedia via YouTube Screenshot

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Bassracerx
Bassracerx
26 days ago

it has got to be reinforcement for that tie rod end link. due the amount of horsepower/speed this thing has plus it’s girth and mass it looks like engineering messaged/strengthened that control arm due to failures in stress tests. I’m curious if that “nub” on the end is some sort of cap that hides large bolts to add support?

only one thing to do now autopian is to buy that spare part from tesla and cut it open with a laser!

Ninefeet
Ninefeet
27 days ago

While talking about intrusion of the wheel in case of crash :
Chalmers crash test short (youtube.com)

Spikersaurusrex
Spikersaurusrex
28 days ago

That’s an Electricity Shark. Like a Fuel Shark, but made especially for BEVs. By smoothing the flow of electrons, it boosts the reactionary uptake and increases range. It also makes you skinnier.

Blockchain.

And They Called Him Gearhead
And They Called Him Gearhead
28 days ago

Came here to say exactly what you already discovered on JLR products.

I’m a factory certified instructor for the green-oval and that aluminum nub, while more pronounced on the Tesla, is in a surprisingly similar location to our “scrapers” and I can tell you internal communication / training has referred to them as exactly that.

The thinking of the part being A. its sacrificial / bolt on for easy replacement (instead of damaging a far more expensive part of the hub B. it’s actually designed to clear debris so it doesn’t easily wedge between the caliper and the wheel, rather than simply aiming to “clear” the wheel itself of mud specifically.

I would be surprised if the Tesla didn’t have similar aspirations for that part.

I’m sure the official JLR communication will be more precise but… Good instincts Lewin!

JaredTheGeek
JaredTheGeek
28 days ago

Based on the shape and location its where the Musk is stored.

Theotherotter
Theotherotter
28 days ago

Based on the shape of the part and the location of the casting lines on the nubbins, they appear to be different parts L vs. R. This must also be for some reason, as this seems like a part that could otherwise easily have been made as a single casting with different machining operations for each side.

Car Guy - RHM
Car Guy - RHM
28 days ago

I’d mount a rubber scraper to it, I have a 18 F150 with 20″ wheels, in the snow or mud, the wheels tend to build up debris on the inner of the rim and then you get an unbalance until you scrape the debris out.

Rust Buckets
Rust Buckets
28 days ago
Reply to  Car Guy - RHM

Aren’t oversize donk rims awesome?

Andreas Jüngling
Andreas Jüngling
28 days ago

Considering the rather large width of the wheels themselves, the nubbin could bridge the gap from the wheel barrel to the knuckle, because the wheel flange and thus the spokes are so far out. That’d stiffen the wheel from the inside as well. Without it, there could be shearing forces that could break it away from the spokes.

Sid Bridge
Sid Bridge
28 days ago

Let’s not count out lazy ingenuity here. If the bolts holding that side of the knuckle on were too long and they had access to aluminum cutting tools but not to shorter bolts…

Jesus Helicoptering Christ
Jesus Helicoptering Christ
28 days ago

it cost me $20 to message him on Twitter thanks to the whole Premium nonsense.

I would like to get off this wild ride, please.

Spikedlemon
Spikedlemon
28 days ago

That’ll be $5/month charge to eliminate the one-time fee.

Ninefeet
Ninefeet
28 days ago

Added on purpose by Tesla to distract people from other dysfunctionnal devices…
And this one works 🙂

Last edited 28 days ago by Ninefeet
Chronometric
Chronometric
28 days ago

It’s called a stannule. It is paired with new Cybertruck owners and stimulates their brain whenever the steer-by-wire changes ratio, the tonneau cover is powered, or a stainless reflection blinds a bystander.

The F--kshambolic Cretinoid Harvey Park
The F--kshambolic Cretinoid Harvey Park
28 days ago
Reply to  Chronometric

> new Cybertruck owners and stimulates their brain

In other words, it doesn’t do anything.

Huibert Mees
Huibert Mees
28 days ago

I think the speculation about the small overlap crash test is correct. The nubbin would promote failure and collapse of the wheel. When a smaller wheel is installed, it may be that it is too small to get in the way during the test, but it also might be that the smaller wheel needs to fail in the same way. That might be why the part of the knuckle that holds the nubbin is still quite long. Even with the nubbin removed, that part of the knuckle is still way longer than it needs to be.

Arch Duke Maxyenko
Arch Duke Maxyenko
28 days ago
Reply to  Lewin Day

Also doesn’t the curb weight mean it actually doesn’t need to be crash tested?

Rust Buckets
Rust Buckets
28 days ago

I don’t know what the regulations are, but I do know that the Cybertruck curb weight is not actually super out of line compared to other crew cab pickups and large SUVs. If a Cybertruck doesn’t need to be crash tested then neither does an Expedition or Suburban.

Arch Duke Maxyenko
Arch Duke Maxyenko
28 days ago
Reply to  Rust Buckets

It’s above 10,000 lbs GVWR

Huibert Mees
Huibert Mees
28 days ago

The small overlap test is an IIHS test, not a government test. I don’t know the details of it, but IIHS might not be limited to 10,000 lbs GVWR. Please correct me if I’m wrong.

Rust Buckets
Rust Buckets
28 days ago

1. Curb weight=/=GVWR

2. The Cybertruck is very literally NOT above 10,000lb GVWR.

https://www.tesla.com/ownersmanual/cybertruck/en_us/GUID-12A976DD-EB60-431B-AFF1-5A37E95006DB.html

SonOfLP500
SonOfLP500
28 days ago
Reply to  Huibert Mees

Maybe it is made of a harder alloy than the knuckle? Hence the machined face to make sharp corners and concentrate stress where it strikes the wheel in a crash test.

Last edited 28 days ago by SonOfLP500
Fuzz
Fuzz
29 days ago

Interestingly the prototype had this entirely molded(not bolted on).

https://i0.wp.com/electrek.co/wp-content/uploads/sites/3/2023/08/Screenshot-2023-08-11-at-3.58.50-PM.jpg

Martian
Martian
28 days ago
Reply to  Fuzz

Maybe they just forgot the part and fast followed. Sort of like FSD! Come on that was funny! 😉

Totally not a robot
Totally not a robot
29 days ago

And here I thought it was like a mud scraper, but for scraping all the meaty bits in the first battle when Skynet takes over and the Cyber truck calvary are activated.

Mechjaz
Mechjaz
29 days ago

> That’s a whole pizza! Or four frozen pizzas! Bah.

Somebody ship a Costco down to Australia, stat. Don’t eat the fresh pizza; it’s intestinal acid, effectively used to clear a, ahem, “full pipeline,” but if they have the Motor City Pizza Co deep dish 2-pack, you’re in for a treat.

Rust Buckets
Rust Buckets
28 days ago
Reply to  Lewin Day

Well the whole point is that the groceries are cheaper. And cheaper by more than what the subscription costs.

Are the gas station lines bad? Where I live there are often lines, but often not, and the wait is never bad.

Morgan Thomas
Morgan Thomas
28 days ago
Reply to  Lewin Day

At our local Costco (actually walking distance from home) the lines are often over a dozen cars long at each pump, and sometimes trail all the way through the carpark and back out onto the road. Fortunately I don’t do many miles in my own cars (but probably 50,000km a year in the work van!) so I don’t need to be tempted by slightly cheaper fuel.

BigThingsComin
BigThingsComin
27 days ago
Reply to  Morgan Thomas

Slightly cheaper? My local Costco is 50 cents a gallon cheaper (for premium) That’s $10 in my pocket each time. I can wait for a bit.

Peter d
Peter d
28 days ago
Reply to  Lewin Day

That is always the question – look at the line, if it is less than 2 cars deep it might be worth the extra time. But much more than that the time and stress of jockeying for position usually will have me stop and pay $0.20 more per gallon (sometimes a little less) at one of the regular stations on the way home.

Mechjaz
Mechjaz
28 days ago
Reply to  Lewin Day

+1 to Rust Buckets and I never, ever buy gas unless I’m going through town ungodly early or have something else to do out and about just before they close down the pumps. It helps I live 2 miles from one; I can just go home and wait until 8:45pm if I’m really hard up for gas.

They’re one of the least-worst 93 octane gougers. Their 87 isn’t always the best price, but it’s close enough that I’ll waste more gas looking to save 3 cents than just going there in the first place, especially when the truck needs a fill up. Their prices times up to 26 gallons is definitely a difference. Same for the Z4 and 93, when she’s roadworthy.

The bike gets 93 wherever; I’m not arguing over 3.7 gallons.

Rust Buckets
Rust Buckets
28 days ago
Reply to  Mechjaz

Where are you located? Here in Idaho(and road trips through Utah, Nevada, ect.), Costco has the cheapest 87/85 octane 100% of the time. Consistently a cent or two cheaper than Maverick(which is always 2nd best), and sometimes more than that.

Mechjaz
Mechjaz
28 days ago
Reply to  Rust Buckets

I’m having trouble finding more detailed numbers since Gasbuddy reports Siler City for Durham, which is useless.

This seems pretty close:
https://www.wral.com/1007163/

Right now Costco is at $3.24 regular, $3.64 premium:
https://www.costco.com/warehouse-locations/durham-nc-249.html

This is below average:
https://gasprices.aaa.com/?state=NC

In the last few days I’ve seen $3.1x here and there. Like I said, it’s only a few cents, but it’s not always the absolute lowest price. Regarding that WRAL link, it’s either missing a few data points or prices have moved around since I went out a day or two ago, and Costco is back to being within a cent of the lowest.

Scoutdude
Scoutdude
28 days ago
Reply to  Lewin Day

Of course I’ve never been to an Costco down under, but it is definitely more than just groceries and gas. On the website it shows that at least some of the locations in your country have tire centers which usually means automotive batteries too. One set of tires will save you more than a year’s membership. Then you have things like motor oil, tools, appliances, TVs and more.

Lines certainly can get long at the pumps but usually move fast but frequently there are times of day when there aren’t lines.

Dangerous_Daveo
Dangerous_Daveo
28 days ago
Reply to  Scoutdude

Yeah, I looked at tyres, the mobile fella was cheaper.

We’ve found the fuel line is ok, it’s prepay and nothing else to buy, so it rattles through quickly.

Scoutdude
Scoutdude
26 days ago

That can make a big difference if you go to the convenience store/station where the person in front of you goes in and spends a lot of time deciding on what flavor of chips to buy, purchases a lottery ticket, ect and then doesn’t know what pump # their car is at. Meanwhile at Costco the only option is to pay at the pump and get on with pumping your fuel.

Crank Shaft
Crank Shaft
29 days ago

The crash mitigation question should be fairly easy to answer if compared to a truck with different size wheels. However, I have no idea if they have yet delivered any with other size wheels, so maybe that won’t help solve the mystery for now.

It seems like a weird place and shape to put a SORB wheel cracker because it would require the wheel to break from the spindle first.

No way is it a mud scraper.

My best guess is that it is part of tie rod crank pin retention. In other words, pull those bolts/cap and the tie rod drops to the ground.

Rust Buckets
Rust Buckets
28 days ago
Reply to  Crank Shaft

They all have 20″ wheels so far, and I can’t imagine they would change that later.

Drive By Commenter
Drive By Commenter
29 days ago

Tuned mass damper? Some brake calipers have those for NVH reasons.

Hoonicus
Hoonicus
29 days ago

That was my first thought. Second was
Don’t be snubbin nubbin rubbin.

Arch Duke Maxyenko
Arch Duke Maxyenko
29 days ago

This, probably needed to help reduce frequencies that would otherwise disrupt the steer by wire

Huibert Mees
Huibert Mees
28 days ago

A tuned mass damper would need to be attached by some flexible means, not solidly bolted on. The mass has to be able to vibrate in order to work as an absorber. I don’t think that’s what this is.

Rust Buckets
Rust Buckets
28 days ago
Reply to  Huibert Mees

Umm….. I’m no expert on tuned mass dampers, but rigidly attached masses absolutely can reduce the amplitude of vibrations. Just by increasing the inertia of the knuckle.

I know better than to correct somebody who is definitely more expert than me, but that sounded really wrong.

Huibert Mees
Huibert Mees
28 days ago
Reply to  Rust Buckets

You are correct but that small piece of metal is not going to change the mass of the entire knuckle by very much. I doubt the resonance of the knuckle was so close to the edge that a small addition made the necessary difference. Mathematically it is entirely possible, it just seems unlikely to me.

Rust Buckets
Rust Buckets
28 days ago
Reply to  Huibert Mees

I absolutely agree, that little piece of aluminum is rather irrelevant compared to the total mass of tire+wheel+knuckle+brakes+tie rods. Just wanting to clarify on mass damping.

Drive By Commenter
Drive By Commenter
28 days ago
Reply to  Huibert Mees

Spitballing there and it didn’t stick. About right given I’m no engineer.

Buzz
Buzz
29 days ago

This mf paid for Twitter

Crank Shaft
Crank Shaft
29 days ago
Reply to  Buzz

Yeah, I was pissed at that too. Hahaha!

TOSSABL
TOSSABL
29 days ago
Reply to  Buzz

To ask a question for a story. Plus he’s an admitted nerd.
I’m just a nerd who doesn’t write, so I’d go with the pizza 🙂

—is it a business expense that can be written off??

Buzz
Buzz
29 days ago
Reply to  TOSSABL

A question that wasn’t answered but did infinitesimally help a bigot legitimize their platform of bigotry. I personally hope it can’t be expensed.

Whoops, I’m taking the Internet too seriously again. I mean, uh, it’s just bants!

TOSSABL
TOSSABL
29 days ago
Reply to  Buzz

When I get there, I remember it also gives us Calvin & Hobbes — and Pogo instantly for free. Not to mention Bloom County
between that bigot and the orange one, I’ve reread all of the above in the last few years. Perfect for when you don’t have a meadow handy

Mechjaz
Mechjaz
29 days ago
Reply to  TOSSABL

After a particularly nasty breakup, I told a friend, “it was rough, but Ex gave me the greatest gift of all.”

“Your freedom?”

“No, the hardbound, archive quality complete collection of Calvin & Hobbes.”

TOSSABL
TOSSABL
29 days ago
Reply to  Mechjaz

[thumbs up!]
-because a smiley isn’t enough

Buzz
Buzz
28 days ago
Reply to  TOSSABL
Last edited 28 days ago by Buzz
Phantom Pedal Syndrome
Phantom Pedal Syndrome
28 days ago
Reply to  TOSSABL

Also Pearls Before Swine and Non Sequitur.

The internet is for killing time while we wait for life to shower us with meaning and happiness.

Last edited 28 days ago by Phantom Pedal Syndrome
Hoonicus
Hoonicus
28 days ago

I hope you’re cumfy.
+The Far Side

Drive By Commenter
Drive By Commenter
28 days ago
Reply to  TOSSABL

The last few years sure have seemed like real-life Calvinball.

Rust Buckets
Rust Buckets
28 days ago
Reply to  Buzz

You are taking it too seriously. “Infinitesimally” is an overstatement, Elon’s cut of $20 is an entirely irrelevant portion of his total wealth. Not that giving Elon more money would actually make him more powerful to do anything.

Clear_prop
Clear_prop
29 days ago

The ‘tool’ marks on the casting look like the layering from a 3D printed mold. Since it is a non-visible non-aerodynamic part, no need to make it pretty.

The F--kshambolic Cretinoid Harvey Park
The F--kshambolic Cretinoid Harvey Park
28 days ago
Reply to  Clear_prop

That was my mom’s approach to my face.

A. Barth
A. Barth
29 days ago

Sandy Munro, CEO of Munro & Associates, is on the same page, but notes a similar uncertainty.

I looked him up: sadly he does not appear to be related to the great Burt Munro.

Abdominal Snoman
Abdominal Snoman
29 days ago

IMO, if it was a mud scraper it would have been more effective if it was on the rearward or bottom side of the tire as that would build up sticky mud where it can shed itself over time due to weight rather than on the front side where it’ll just build up and eventually make its way into cooling vanes of the rotor. So totally voting on the crash test argument.

Paul B
Paul B
29 days ago

Even with all the possible reasons mentioned, there is no need for it to not be integrated into the casting.

Unless they’re waiting on a new casting tool, but expressing a new tool would still be cheaper than this solution.

Peter Vieira
Peter Vieira
29 days ago
Reply to  Paul B

It could be that the bolt-in extension was chosen so the gap between the part and the wheel could be easily altered to suit different wheel sizes.

Crank Shaft
Crank Shaft
29 days ago
Reply to  Peter Vieira

See my comment. I’m reasonably convinced it holds the steering system together.

Alexk98
Alexk98
29 days ago
Reply to  Peter Vieira

I’d assume this is the case, two tapped holes per knuckle and an add on nubbin is a lot cheaper and quicker to implement than an entirely different casting, part number, production procedure, and inventory management process, when this works presumably just as well.

Scoutdude
Scoutdude
28 days ago
Reply to  Alexk98

You wouldn’t need a different casting, just different machining of the same basic casting, which isn’t uncommon. Yes it would mean more material would end up as chips, which of course does have a cost. However with this design they have additional machining required of at least drilling and tapping holes for those bolts. They also have an additional casting that needs its own sets of, admittedly less expensive tooling, machining of the nubbin, bolts and another step where someone adds that nubbin to the main casting.

Bizness Comma Nunya
Bizness Comma Nunya
29 days ago

I don’t think I’m right, but the only thing I can think of would be to help limit steering?

I had bolt-on nubbins on a 2005 Volvo S60 that physically limited the travel distance of the wheel while turning. If you took the nubbins off, the wheel would hit something at full lock.

It was a dumb design, and for anyone looking at early 2000s S60s/V70s… they had a hilariously bad turning radius, especially in the R form that I had.

Clark B
Clark B
29 days ago

Ah yes, I remember the turning radius of the 2001 V70 I grew up in. We had the larger wheels and they always rubbed at full lock.

Scoutdude
Scoutdude
28 days ago

It wasn’t uncommon in the early days of optional larger tire and wheel packages to have some sort of add on stop for those cars with the larget tires and wheels.

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