By on March 27, 2018

As you would expect, most of the reaction to Cadillac’s announcement of the 550-horsepower CT6 V-Sport centered around its engine, a “clean-sheet” 4.2-liter V8 that is either meant to slavishly ape the current German fetish for diminutive, twin-blown bent-eights or cash in on all that nostalgia for the Northstar and its litany of opportunities for improvement. I’m not sure which.

I don’t know about you, but I think it makes sense to develop a whole new powerplant for the CT6 because, if there is one thing that GM does not already have, it is an exhaustively developed, amazingly compact, remarkably lightweight, and impressively powerful V8 engine. Honestly, the whole thing reminds me of the time that I accidentally bought a used DVD of “Cloverfield” at a Blockbuster Video sale only to get home and discover that not only did I already own a used DVD of Cloverfield, the one I’d just bought had a big scratch in it. Oh well. If nothing else, this new CT6 V-Sport will increase the alacrity with which the tatted-up part-time-barista grandchildren of Boomers await their death and subsequent estate distribution. Grandpa might have left you the ’57 Strat, but he left me that wacky thing that looks like a normal Cadillac Escalade but sits really low on the ground for some reason!

The Son O’ Northstar wasn’t the only technological innovation reported in the press release, however. When the CT6 V-Sport hits the streets, it will feature the largest front brakes ever fitted to a production automobile, eclipsing the 17.3-inch rotors of the Lamborghini Urus with a 19-inch system sourced from Brembo. Even more surprisingly, the whole thing fits snugly inside 20-inch wheels. This new innovation was reported across hundreds of media outlets in the automotive, business, and popular-interest press.

There is just one little issue: it can’t be true.



And why can’t it be true? Who says domestic cars can’t lead the way in braking? After all, the C6 ZR1 used carbon-ceramic discs that were similar in size and composition to the ones that debuted on the Ferrari FXX hyper-hyper-super-car. It even came with special brake booties to use during servicing. So let’s not get all bigoted about this idea that only Italian exotics or German bruisers can sport world-class stopping power, alright?

In the case of the V-Sport brakes, however, it’s less a matter of bigotry than it is of mechanical engineering. With a few wacky and wonderful exceptions, such as the Sbarro Orbital Wheel, disc brakes tend to be clamped by calipers that surround the outer edge of the disc at one point.

As you can see, if you want to fit a wheel over a set of brakes it’s not enough for them to be bigger than the rotors. They also have to be big enough to clear the calipers. This is one of the major reason that today’s wheels are just so darned big; they have to fit over big brakes. In order for Cadillac to fit 19-inch rotors inside 20-inch wheels, they would have to create a set of calipers that extend less than half an inch past the discs. This is theoretically possible, but it amounts to some very tricky on-the-edge engineering and I’ve never seen anything that would come close, even in Formula One or on high-performance motorcycles. The clearance issue is a big enough deal that when Wilwood was able to make 12-inch discs fit in 15-inch wheels it was treated as serious news in the vintage-car community.

It’s highly unlikely that Cadillac has managed to fit anything more than a 15.3-inch rotor in the CT6. Sixteen inches, maybe, although that would be expensive to say the least. Nineteen inches is outside the realm of possibility, unless they’ve completely reinvented the caliper brake. That would be awesome, but it would also break the bank on a car that can’t afford to be the most expensive vehicle in the segment. So here’s the question: Why did hundreds of outlets report the 19-inch brakes without a moment’s worth of critical thinking?

To my knowledge, the only person who read the press release and actually thought about it was our own Bozi Tatarevic, who then alerted me to the problem. I read the press release for myself and sure enough, it was claiming 19-inch brakes. It’s obviously a typo, but how did it slip by so many people, both inside GM and out in the so-called real world?

You can blame it on a historically unprecedented level of ignorance among the automotive press. Forty years ago, the “buff book” writers were often credentialed engineers and auto-industry veterans like Patrick Bedard or frustrated club racers like (insert a dozen names here). As recently as the turn of the century the vast majority of people who wrote about cars had some nontrivial hands-on experience with them, even if it was just changing their own oil and rotating their own tires.

We are no longer in that particular part of Kansas, Toto. Many of the most prominent writers and “influencers” live in New York apartments. Some of them have never owned a car. A major percentage of the modern spend at a new-vehicle release goes to social-media celebrities, travel journalists, and other people who have no genuine interest in, or knowledge regarding, automobiles. They’ve never changed brake pads or even changed a flat tire. How could they know that a 19-inch rotor won’t fit inside a 20-inch wheel?

To further complicate issues, we have gone from a monthly news cycle to an hourly news cycle with a voracious appetite for what we non-judgmentally call “content.” That CT6 press release was just another piece of content. Sites like Jalopnik, Autoblog, and even TTAC are now dependent on a revenue model where they take daily press releases and re-phrase them for general consumption. There isn’t time to devote real attention or thought to that content. It doesn’t pay any better and the readers won’t reward you for doing so.

That’s how you get three hundred news stories about magic brake rotors. Everybody needs news, nobody has the time to proofread it, and very few people have the knowledge that would be required in order for said proofreading to be useful. Moreover, as we saw with Buick’s embarrassingly illiterate response to our Death Watch piece two weeks ago, the automakers are increasingly putting their PR and social-media presence in the hands of people who are, to be brutally frank, not grown-up enough to do the work.

What’s the end result of all this? I’m afraid that it’s yet another area in which the consumer is being asked to shoulder additional responsibility. You’ll be doing your own-fact checking the same way you handle all of your own bank transactions via ATM or phone app, deal with your travel reservations through clunky websites, and even order your own Quarter Pounder on a touchscreen so you can avoid having an extended interaction with an openly hostile counter person who may or may not fully grasp the language you’re speaking. Is there a better way to do it? Sure, but that better way costs money in a world where the price of automotive news has generally settled around the $0.00 mark. When it comes to making a choice between good and cheap, Americans have overwhelmingly picked the latter over the former.

Let’s hope that the brakes on the CT6 V-Sport are better-sorted than the press release is. Or maybe it’s all an early April Fools’ prank and the CT6 will really have that 6.2-liter small-block and, oh, I don’t know, a stainless-steel roof. If we’re going to dream, let’s dream big. And if we’re going to make up 19-inch rotors, why not make up a new generation of indecently rapid Broughams under which they might be fitted?

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64 Comments on “No Fixed Abode: The Nineteen-Inch Mystery...”


  • avatar
    tallguy130

    And that’s why I read this site. At least someone is calling people on their bull #%@$

  • avatar
    phila_DLJ

    Thankfully the official CT6 V-Sport website does not make any mention of brakes, impossibly sized or otherwise (nor does Jalopnik, from what I can see).

    I wonder who was patient zero for the erroneous 19″ figure.

  • avatar
    phila_DLJ

    By the way Jack, are you working on anything, either here or over at R&T, about the Uber snafu?

  • avatar
    NoID

    Maybe you’ve got it all wrong. Maybe they messed up the wheel size…

    Though I must say I’m far more inclined to believe the rotor diameter is the fib. On a car as (relatively) light as the CT6 I see no practical reason to fit 19 inch brakes.

    Maybe they accidentally cribbed the number from the as-yet-unannounced Escalade V.

  • avatar
    JimC2

    Yes, but I want to hear about the hard plastic bits that give the interior a cheap feel.

    That’s pretty funny that their own press release would get through with that mistake. Maybe the rotors are turned inside-out and the calipers don’t actually go *around* the rotor… ha! (Not.) If it weren’t a major bragging point about the car then it wouldn’t matter as much- it’s not like they were talking about rear seat legroom or something minor like that.

    12″ rotors inside 15″ wheels is quite respectable. Your Hot Rod article is about brake upgrades in a highly modified 1960s B body; the 1970s A body Mopars came from the factory with 11″ rotors inside 14″ wheels with single piston sliding calipers- quite good stopping power in their day (Dart/Valiant front disc brakes). Old Volvos came with big fat 4-piston Girling calipers and 10-point-something inch rotors inside 14″ wheels (which is outstanding stopping power in vintage cars).

    On the thought of never getting one’s hands dirty doing a brake job or changing a flat tire, I’d wager that would describe most people on the design team for most any modern car, including the CT6. It’s kind of a shame.

  • avatar
    Advance_92

    Those would be heavy as hell.

    • 0 avatar
      JMII

      Could be a two piece design to save weight but 19″ is pure BS unless the wheels are 24″ which would be crazy, but not unheard of these days on a SUV.

      I’ve got 14″ Akebono brakes under 18″ wheels on my 350Z and trust me there is NO way to get anything bigger in there. As is I’ve about wheel balance weight’s gap between the wheel and the caliper! I’ve seen some Porsches that have pretty tight fitment, but most stock systems are generally conservative in brake rotor size. In my example the brakes I have are actually designed to fit the 19″ wheels.

  • avatar
    Gail Bloxham

    Ok Mr. SmartiePants… ever hear of a 2CV?
    Maybe you might want to look at the brakes?
    I’m not saying or even implying Cadillac is planning anything like that. I’m just saying… there is more than one way to skin a cat. Or design front brakes.
    . Out of the box dude. Think.

  • avatar
    ajla

    Inboard brakes obviously.

  • avatar
    1500cc

    Two words: inboard brakes ;)

    edit: ninja’d!

  • avatar
    krhodes1

    Maybe a return of the old Audi “UFO” brakes with the caliper on the inside? Or maybe these things will actually have 22″ wheels? Either way, I could not possibly care less. And add me to the list of those baffled as to why GM thinks they need another useless V8. It’s not 1950 anymore, kids.

    If they want a flagship they should conjure up the stones to put a V12 in the thing. V8s are for the proles. Or better yet, since this IS Cadillac, a V16.

  • avatar
    jonsey

    After reading the car review publications for a few years, it seems to me they are all captive advertising arms of the automobile manufacturers.

    I was reading a review of the successor to the Ferrari California, the Portofino, on Car and Driver. Apparently, now the Portofino is out, the California was really an ugly piece of crap. Look at the guy in the pictures driving that car. He’s a 20 something. How qualified is he to compare the California and Portofino? I wouldn’t care if it were just Ferraris. But it is all cars. Over and over you will see this pattern. The automotive press sings praises about a model until the new version comes out. Then it’s OK to trash the old one.

    If you read all the reviews of a new car at launch, you’ll notice each review points out the same features of the car. That’s because they’re all using the talking points the manufacturer provided. I noticed this especially with the latest Mustang.

    It makes sense if you think about. The automotive press doesn’t exist to serve the consumer. It exists to sell magazines and web clicks. The best way to do this is cosy up to the manufacturers for free reviews, glamorize the models as much as possible and help sell cars.

    • 0 avatar

      Yes, but the best part is the real review of the *outgoing* vehicle is in the new vehicle’s review.

      “The crappy seats have been fixed”, or “the engine has been redesigned” (we fixed the bad water pump design costing thousands) or “the shifter is revised for this model” (prior was a spoon in a paint can). “the prior turbo has been discontinued” (because it was a poorly engineered nightmare)

    • 0 avatar
      hpycamper

      Agreed. My favorite is when the reviewer points that the Audi under review has a single frame grill.

  • avatar
    dwford

    I stopped reading the article about the CT6 V-Sport after the description of the engine. I got scared and had to go lay down. Cadillac has a long history of bespoke engine nightmares, and this new one sounds sufficiently complicated enough to extend that history.

  • avatar
    MrIcky

    I’ll fess up as a modern auto article consumer- I usually read these articles at work, and it’s not often I read for detail. Then I see if any of the B&B make me chuckle. Then I’m back to work or skipping off to a mountain bike site that I split my attention with. So lazy press release, repeated by lazy journalist, and then read un-critically by distracted consumer.

    Even when I do have the time to read critically, there’s so much snark and narcissism of small differences that it’s hard to read anyway.

    So, I guess I’m getting the auto-journalism I deserve.

  • avatar
    drivin98

    So what did Cadillac say after you called them up and inquired about their 19-inch rotors?

    Or did you forget about doing that part, thrilled as you were with the opportunity to bash other writers to make yourself look good, and make up fairy tales about the paucity of their auto ownership and opulence of their living conditions? (Yeah, a New York apartment is not opulent, but it costs as much as opulence in most other parts of the country. This is to say, more than most auto writers can afford.)

    I mean, I read through this entire article, and all I learned is Bozi has a keen eye (which I knew, so I didn’t even learn that, but just had it reinforced).

  • avatar
    dukeisduke

    Never mind the brakes, I don’t believe that the CT6 V-Sport’s V8 will be exclusive to Cadillac, either. Peter DeLorenzo over at The Autoextremist believes it will appear in 5.5 liter form in the mid-engined C8 Corvette. Think GM would spend the money to tool up something like this, then put it in maybe 2,000 cars a year? Yeah, me neither.

    • 0 avatar
      Jack Baruth

      Another thing Bozi pointed out is that this is more or less the 3.6 with two more cylinders.

      • 0 avatar
        dal20402

        And a different bank angle. Cadillac’s press release says it’s a 90-degree engine.

      • 0 avatar
        28-Cars-Later

        If its just a rehash of the GM LFx family it could be Cadiwreck “exclusive” and will function as such (in other words, as an oddball with the risk of edge case type issues). Cadillac is the new Oldsmobile, the practice brand for things eventually rolled out to core Chevrolet + B/GMC. They must love their customers.

        Too bad they don’t have a V8 engine family already it had to be developed…

  • avatar
    sportyaccordy

    Even if somehow this thing came with 19″ rotors, the absurdity of a “ring tuned” limo is the bigger travesty here.

    The world needs this like Forza lobbies need rammers in Caddy limos with “TRUMP RLUES” hastily typed on the side (in the color of sovereignty and civilization of course).

  • avatar
    dal20402

    Maybe the PR people are trying to redefine what brake diameter means to sound more impressive. Could it be the “diameter” of the whole system including calipers? That could possibly approach 19″ under a 20″ wheel, maybe.

  • avatar

    You’re discounting wheel offset. This may make it possible.

    You, of all people, should know that many of our favorite cars went through dramatic offset changes over generations to clear bigger and bigger brakes (and the introduction of ABS), rendering the prior generation of wheels useless – despite having the same hub bore diameter and bolt pattern.

    • 0 avatar
      JimC2

      That’s a possibility and a good point, but it would be one heck of an offset. Google says the last generation of the car’s wheels were 19×8.5 with 33mm offset (about 1 1/4″ offset). The rotors can make up some of the difference by being extra wide and having more of their own offset from the rotor to the hub face. The only thing from keeping the proportions from looking even more ridiculous would be the already large (ridiculous) wheel diameter. I’d love to see one up close or in a picture.

  • avatar
    brandloyalty

    Not to mention the magic of a “new innovation”, as mentioned in the article. Old innovations are just so pedestrian.

  • avatar
    MoparRocker74

    “This is one of the major reason that today’s wheels are just so darned big; they have to fit over big brakes.”

    This has become a vicious circle. Yes you can fit bigger brakes in bigger wheels, BUT bigger wheels are heavy as hell and taller diameter so guess what…you need bigger brakes to stop them.

    Personally I hate big rims. They make everything look like a stagecoach or a steam locomotive. I mean, didn’t tall skinny rims with rubber band tires go the way of the dodo back in like the 30s? 18″ seems to me to be the practical limit. Ive sold off factory 20’s on 2 vehicles –’05 Ram Rumble Bee and ’09 Challenger R/T. The Ram went on 17’s, the Challenger on 18’s. In both cases they looked better but that’s subjective–I prefer the old school beefy tire and deep dish wheels look. What is concrete is that by shedding that extra weight and gaining some sidewall both accelerate like crazy, brake much better, handle road imperfections much better, and the ole’ butt dyno doesn’t notice a bit of lost cornering ability. The Ram ended up benefiting the most, likely since those wheels were heavier than the R/T’s, the new rim was a bit smaller still, and it got a 2/4 drop being 2wd. Big rims are just chasing the fad of the early ’00s and its not making our cars better.

    • 0 avatar
      turf3

      A luxury car with tires 2″ high and the resulting jittery-jigger ride is just plain stupid.

      If I go to buy a luxury car I would like to see 15″ wheels with 65 series tires.

      Don’t tell me you can’t lock up all 4 wheels with that combination.

  • avatar
    phoon

    Nice catch on the breaks, will be interesting to see what they really are. Why the negativity on the motor though??? Bring on all of the v8’s!! This motor is lighter than the supercharged LS and will no doubt suit the character of a large luxury sedan much better than a musclecar motor LT4/LT5.
    550 hp and 627 ft lbs of smooth power should never be complained about, time to ditch the negativity.

  • avatar
    NeilM

    You really can’t have front wheels with massive offsets. The virtual steering axis at each front wheel needs to pass through the tire, not inboard of it. Otherwise you get massive steering offsets and unworkable suspension geometry. In practice at least the lower pivot point that determines this axis (in the case of MacPherson struts) or both pivot points (A-arm or multilink) have to be very close to the wheel, or in the case of the lower pivot, even slightly recessed into it.

    This would preclude a large setback of any putative outboard brake rotor from the outer plane of the wheel.

    Since the CT6 is AWD, and therefore already has front driveshafts, they could do inboard brakes. However cooling those brakes then becomes a problem. Front brake rotor service would be a nightmare, although changing pads might not be too bad with a lift.

    But I’d bet that it’s a simple typo at Cadillac that’s propagated itself out through all the publicity materials. The number 9 is right above the 6 on a numeric keypad, and while 16″ rotors would still be pretty large, they’re not inconceivably so.

    • 0 avatar
      JimC2

      “You really can’t have front wheels with massive offsets. The virtual steering axis at each front wheel needs to pass through the tire, not inboard of it. Otherwise you get massive steering offsets and unworkable suspension geometry.”

      Standing by for the next press release: Cadillac announces another industry ‘first,’ the world’s first 5,000psi power steering system on the all-new CT6.

      “… they could do inboard brakes. However cooling those brakes then becomes a problem. Front brake rotor service would be a nightmare”

      Must… resist… saying something snarky… about ease of maintenance and certain brands…

      • 0 avatar
        millmech

        EEEEEEK!!!!! A flash forward, the newer military planes can’t be flown by human beings without a lot of help from computers. How long will it be before cars built with stuff like this will need the help of computers just to go down the road?
        How close are we to that already? Gimme a BREAK!!! I’m trying to text!!

  • avatar
    NeilM

    Weirdly enough the exact same published specs paradox came up 4 years ago with Audi:
    http://www.audizine.com/forum/showthread.php/592860-S6-Ceramic-Brakes-Retrofit

  • avatar
    W.Minter

    GM is absolutely correctly and willingly misleading. They say it is a “a new 19-inch Brembo brake system”. Any word about rotor size? No. 19 in is probably just the combined diameter of caliper(s) and rotor. Of course, everyone else in the world uses the word “system” together with rotor size.

    And the Caddy/Brembo System is just a boring 4 piston mass market design. Jaguar used a 6 piston Alcon system in the XKR-S portfolio (with 400 mm rotors), and methinks there are also dual caliper designs (4+2 pistons), but I can’t remember where I’ve seen it.

  • avatar
    Flipper35

    Given that the inner barrel is smaller diameter than the outer rim where the bead of the tire is the 19″ rotor would not fit even if they clamped down with the pistons inside the diameter of the rotor unless the rotor is part of the rim. No amount of offset can fix that issue either unless the offset is far greater than half the width of the wheel. Don’t see that happening as it would totally screw the scrub and geometry.

  • avatar
    RonSinger

    Actually, it can be true.
    Notice that they said the car had 19″ brakes. They didn’t claim to have 19″ rotors. While it is correct that a brake package using a 19″ rotor would never fit inside a 20″ wheel, the designation ’19 inch brake’ refers to a brake system that is designed to fit in a 19 inch wheel. Obviously it will also fit in a 20 inch or larger wheel, but an 18 inch wheel will not fit over a 19 inch brake.

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