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Discussion Starter · #1 ·
I am not sure why this stirs up so many arguments, and also not sure why so many people when it comes to car chassis building want to argue on this, but let's set the record straight, and also give a few of my opinions which may or may not be gathered in fact. I am begging @Aloppen to stop by and tell me if I am right on, or out to lunch on this? Unibody vehicles are built in many different ways, but by definition if the main chassis structure and the body are integrated that is a unibody (GM calls the Hummer EV an Integrated body and structure). The reason for doing it on the Hummer EV is clear, you get a much stiffer chassis, without having to massively over build the frame, making it heavy and expensive to build. Case in point on stiffness, how many people have noticed a typical pickup has a gap between the cab and the bed, do you wonder why? In a typical body on frame pickup the frame has quite a bit of flex when you are maneuvering through certain terrain and if there was not an "joint" in the body you would wrinkle the panels when you twist the truck. Modern trucks have made this better with fully boxed frames, but everyone knows they could build them into a unibody they would be stiffer, lighter and cheaper, so why do OEM's build pickups body on frame? From my understanding this is because body on frame is more flexible in the factory when you have multiple wheelbases, cab configurations, and bed lengths all being built on the same lines. They can just roll the frame upside down to install certain components, and then roll it upright to marry the body. A body on frame pickup is what Elon Musk made fun of in the Cybertruck presentation, and when he stated that the cab and bed are just extra cargo along for the ride, he was right, the cab and bed do not add significantly to the structural integrity of the chassis in certain bending moments. Now back to the Hummer EV, we know it has a very heavy battery adding weight, so to try to save weight and get a stiffer chassis I think GM engineers decided to integrate the structure and body, there are sound engineering reasons for this, as any engineers know, when you build a structure to transfer loads, often the taller the structure can be the more load you can transfer without unsatisfactory deflection, or heavy / expensive materials. On a pickup truck frame you do not have much height to work with unless you want to lift the truck extra high (or have low ground clearance), but in the case of the Hummer EV, you can use the structure of the cab, and bed to reinforce the understructure, and also use the battery enclosure for further reinforcement you get an incredible stiff structure. I am pretty certain from looking at it the Hummer is the stiffest chassis GM builds, both front to back and side to side. Now, there is one reason a Unibody is not ideal for a low production vehicle like the Hummer EV, and that is factory setup cost... Unibodies are mostly put together using automated systems in the body shop, and those systems are expensive and not flexible for changes, so how does GM amortize the cost of the body shop setup for the Hummer EV program, step up and let me introduce you to the Silverado EV. Now this is my opinion, but I think the Silverado EV will sit on the exact foundation that is under the Hummer EV. Of course the Silverado EV will not have all the cool off road gizmos, and likely a cheaper suspension system, but I am going to guess that the internal structure, from the cowl down are nearly identical. I am now going to attach some pictures and comment on what I see...

Let's start with the painted Hummer EV Body. Interestingly GM seems to be painting the bottom of this structure, this is great news as it should be more resistant to rust, and other failures, and well for an anal guy like me that details my cars top and bottom, it just looks a lot nicer. Will the painted underside make production? I sure hope so. In this picture you can clearly see the structure is massive.
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The next picture shows Mark Reuss looking at the underneath of the structure, I think he is looking at the rear suspension mounting hard points, and clearly you can see that this is a prototype part by the "X's" marking bends and weld points.
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The next picture is further back from that same chassis, this shows the backbone I think will be shared between Hummer and Silverado EV. I was assuming the Silverado EV will have a slightly shorter wheelbase and obviously the top hat (windshield frame, roof, and rear window) will be unique. When you look at this structure, its obvious that is going to be stiff as heck.
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The last picture shows a closer image of the firewall, again, that is a structural part bracing the chassis in side to side, and twisting moments, this is exciting to see. Damn, I cannot wait for mine.
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GM showed the Silverado EV at the Barclays conference, it's obvious it is on the same platform, and I venture to guess shares a lot of parts with the Hummer EV.
 

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For me, I typically think of a unibody as having the suspension parts directly mounted to the body, not to a separate frame. There are two pictures of the new EV platforms on the GM web site, one for the BEV 3 platform, and the other for the BT1 platform. There is a difference that is quite clear between these:

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Discussion Starter · #3 ·
For me, I typically think of a unibody as having the suspension parts directly mounted to the body, not to a separate frame. There are two pictures of the new EV platforms on the GM web site, one for the BEV 3 platform, and the other for the BT1 platform. There is a difference that is quite clear between these:

View attachment 866
View attachment 867
For me, I typically think of a unibody as having the suspension parts directly mounted to the body, not to a separate frame. There are two pictures of the new EV platforms on the GM web site, one for the BEV 3 platform, and the other for the BT1 platform. There is a difference that is quite clear between these:

View attachment 866
View attachment 867
Whatever you assume, it's just not right... Many unibody cars have subframes front, and some rear. Think late 60's Nova, Camaro, etc, etc, etc... Body on frame means the frame is a separate structure, that the body is bolted to, but if the structural framework is welded to the body structure, utilizing the body to reinforce the structure, that is unibody... Period!!! The Hummer does not ride on a true skateboard structure, that skateboard is built directly into the body structure and welded. You are not taking the cab or the bed off the Hummer EV without a cutting torch and grinder. GM showed the cutaway you posted, but that is deceiving, as to how the structure is built for the actual vehicle. Those which look like frame stringers in your picture are actually part of the unibody. There is a front cradle bolted to the bottom which holds the drive unit, and lower suspension hard points. I would imagine there is a rear cradle as well. Anyway, if you repeat that Hummer is Body on Frame, that is just an incorrect statement and "GM Authority" just got this wrong in the post you made yesterday on the BT1 vehicles. Hummer is a Unibody vehicle by definition, you can twist or spin it any way you like, but you will just be incorrect.

BTW, the Lyriq will also have front and rear cradles to hold the lower suspension and drive units, this is done for assembly in the factory, on the final assembly line the cradles show up with all the parts together and they they are bolted in the bottom all at once. So on Ultium cars or trucks it seems there are 3 main parts bolted on the bottom on the assembly line, the battery pack, and the front and rear cradle, thats it. Keep is very simple, no huge and expensive marriage stations like the T1 trucks have.
 

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Discussion Starter · #5 ·
I disagree. I think they will remove the body from the frame to do any battery replacement. Time will tell.
Nope, the battery is bolted in from the bottom, dealerships have been supplied special lifts to remove the battery pack while the hummer is up on the lift.

Look at the structure, and tell me where they unbolt the body? That is all Welded...

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Look at the this photo of the battery being installed... From the bottom...
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Show me where the body unbolts? Thats a welded unibody...
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Discussion Starter · #6 ·
I disagree. I think they will remove the body from the frame to do any battery replacement. Time will tell.
Another picture of the battery being installed from the bottom.... And you can see the fully welded unibody even better here... No bolted on frame...
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Discussion Starter · #7 ·
I disagree. I think they will remove the body from the frame to do any battery replacement. Time will tell.
For comparison, lets look at a T1 cab and body going on the frame... See any difference? In the middle picture see the fully dressed frame with engine, trans, and even bumpers installed already...
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Now are you getting it?? T1 has a body bolted on the frame... Hummer a unibody structure... Hummer structure is stronger, lighter, and cheaper to build in volume.

Hummer looks like this being built, then the exterior skins are installed.
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Discussion Starter · #8 ·
I see your point to a degree, but you’re coming off as condescending toward everyone. It’s just a vehicle forum for a completely new platform. Lighten up…you’ll live longer.
Sorry if you feel I am condescending, I am really trying to drive home the point though that the Hummer EV is more then just throwing some batteries under the T1 platform and replacing the Duramax diesel with an electric motor. This is a really special platform, a first for GM, and I think will be seen as the way to do it going forward, especially as volume ramps up. Ford could have done this on the Bronco, but they were lazy and just slapped the Bronco on a body on frame platform (still looks amazing, but nothing revolutionary IMO) I come at this as a GM investor (Also Ford, Tesla, Magna, and Lucid) , and also an enthusiast of EV tech. I also have been around the car industry my entire adult life, although through racing, and a Detroit outsider, so I have been in a lot of these plants, met a lot of plant managers, and used to get great behind the scenes access to the body shops specifically as one of our family friends owned the company that made most of GM, and just about everyone else's body shop tooling incl Tesla, they later sold the company and retired so my access is not as good as it used to be, but I still see people in the body shop robotic tooling industry from time to time.
 

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Discussion Starter · #9 ·
I wasn’t looking for an apology. I was trying to help reach more people as you are clearly passionate about this topic. But let’s start with the “apology”: an apology for how someone “feels” isn’t an apology. Second, these are some of the objectively condescending comments that will turn people off to your message.

Reply however you want. Then forget about this thread and enjoy your weekend. That’s what I’m going to do😀
I wasn’t looking for an apology. I was trying to help reach more people as you are clearly passionate about this topic. But let’s start with the “apology”: an apology for how someone “feels” isn’t an apology. Second, these are some of the objectively condescending comments that will turn people off to your message.

Reply however you want. Then forget about this thread and enjoy your weekend. That’s what I’m going to do😀
Now come on... I made a comment, to which you posted that you disagreed, so I took the time to give you my insight, photos, and even show you the alternate truck construction method. Yes, I made a few flip comments in the meantime which might offend somebody, that I acknowledge, but it's all in fun. At least now you have the information about how the battery is installed and if you want to continue to disagree, that is Ok. I would think photographs of GM engineers putting it together would be convincing, but I am sure not for everyone?


I started the original post with "I am not sure why people want to argue over whether the Hummer is a unibody or not", right? There is nothing to argue about, GM calls it an "integrated body and structure" and Mark Reuss even called the Hummer EV a "Unibody" in one of the investor conferences. I guess Unibody makes people think about a small cheap economy car, but in this case it's a great thing for the Hummer EV.
 

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@Shaved Ice and @Tom E-Tron,

No need for anyone to apologize, you're just having a passionate debate about the Hummer. No names were called, no one was verbally attacked as far as I can tell, so it's all good! 👍👍 Thank you both for so actively engaging the forums.

As far as the topic of discussion, I get both points. In the end, I see what Tom is saying, and more or less I think he's correct on the chassis. But like Shaved Ice has said, I too also think of this truck as a body on frame platform, in the traditional sense.

I think the confusion comes from the whole battery structure thing...it really complicates things from a traditional car talk perspective.

The main thing to note is, yes, the "body" is welded to the "frame" in what we usually refer to as the unibody design. It goes down the line all on one piece, again, like a traditional unibody.

However, and this is where Shaved Ice and I toss a wrench into it, the BT1 is strongly based off the traditional body-on-frame T1 truck platform. It's not identical by any means, but the T1 provided the base backbone to the BT1 architecture.

The long answer here is, that the BT1 is pretty much a BOF/unibody hybrid of sorts, starting out with a T1 truck platform, adding the battery elements, and then using a welding process to turn the whole unit, body and battery/frame construction into one single piece. So in that sense, yeah it's a hybrid, but it definitely leans more towards a "true" unibody than a "true" BOF. That make sense?

I'm no expert here lol, so that may be an oversimplification. I noticed Al Oppenheiser was tagged, and maybe he can clear this up if he checks in. Unfortunately, he's a busy man, and hasn't signed on in quite a while, about 2 months.
 

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Discussion Starter · #11 ·
@Shaved Ice and @Tom E-Tron,

No need for anyone to apologize, you're just having a passionate debate about the Hummer. No names were called, no one was verbally attacked as far as I can tell, so it's all good! 👍👍 Thank you both for so actively engaging the forums.

As far as the topic of discussion, I get both points. In the end, I see what Tom is saying, and more or less I think he's correct on the chassis. But like Shaved Ice has said, I too also think of this truck as a body on frame platform, in the traditional sense.

I think the confusion comes from the whole battery structure thing...it really complicates things from a traditional car talk perspective.

The main thing to note is, yes, the "body" is welded to the "frame" in what we usually refer to as the unibody design. It goes down the line all on one piece, again, like a traditional unibody.

However, and this is where Shaved Ice and I toss a wrench into it, the BT1 is strongly based off the traditional body-on-frame T1 truck platform. It's not identical by any means, but the T1 provided the base backbone to the BT1 architecture.

The long answer here is, that the BT1 is pretty much a BOF/unibody hybrid of sorts, starting out with a T1 truck platform, adding the battery elements, and then using a welding process to turn the whole unit, body and battery/frame construction into one single piece. So in that sense, yeah it's a hybrid, but it definitely leans more towards a "true" unibody than a "true" BOF. That make sense?

I'm no expert here lol, so that may be an oversimplification. I noticed Al Oppenheiser was tagged, and maybe he can clear this up if he checks in. Unfortunately, he's a busy man, and hasn't signed on in quite a while, about 2 months.
Thanks, I appreciate your comment, but unfortunately you are also incorrect, the structure of the Hummer EV is not in any way based off the T1 pickups, and I mean not 1 shared part across the structure or body... Not one! T1 is a traditional body on frame, Hummer not only is a completely new design, it does not share any structural component dimension with the T1 trucks. Now on Interior and accessories they do have some shared parts, seat frames look to be the same, door handle, and maybe the steering column. This is so simple, Its a unibody, just look at the structure in the photos I posted (there is no such thing as a hybrid, it is either a BOF or a unibody), no body on frame anything looks like that. OK, you did it now... haha! More pictures...
Here are definitions, which one fits and why?


Body-on-frame is a common motor vehicle construction method, where a separate body or coach is mounted on a strong and relatively rigid vehicle frame or chassis that carries the powertrain (the engine and drivetrain) and to which the wheels and their suspension, brakes, and steering are mounted. While this was the original method of building automobiles, body-on-frame construction is now used mainly for heavy trucks, pickups, and predominantly large SUVs.

Unibody

A type of body/frame construction in which the body of the vehicle, its floor plan and chassis form a single structure. Such a design is generally lighter and more rigid than a vehicle having a separate body and frame.

Look closely at this photo showing the bed attachment to the cab, there are no frame rails there at all, the body structure is transferring all the loads through the most stressed part of the chassis.
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Thanks, I appreciate your comment, but unfortunately you are also incorrect, the structure of the Hummer EV is not in any way based off the T1 pickups, and I mean not 1 shared part across the structure or body... Not one! T1 is a traditional body on frame, Hummer not only is a completely new design, it does not share any structural component dimension with the T1 trucks. Now on Interior and accessories they do have some shared parts, seat frames look to be the same, door handle, and maybe the steering column. This is so simple, Its a unibody, just look at the structure in the photos I posted (there is no such thing as a hybrid, it is either a BOF or a unibody), no body on frame anything looks like that. OK, you did it now... haha! More pictures...
Here are definitions, which one fits and why?


Body-on-frame is a common motor vehicle construction method, where a separate body or coach is mounted on a strong and relatively rigid vehicle frame or chassis that carries the powertrain (the engine and drivetrain) and to which the wheels and their suspension, brakes, and steering are mounted. While this was the original method of building automobiles, body-on-frame construction is now used mainly for heavy trucks, pickups, and predominantly large SUVs.

Unibody




Look closely at this photo showing the bed attachment to the cab, there are no frame rails there at all, the body structure is transferring all the loads through the most stressed part of the chassis.
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I believe I've read a statement from Mark Reuss or Duncan Aldred mentioning something about the BT1 being based off the T1. I could be wrong Tom, since this was way back before you joined the forums, but this used to be accepted fact around here back when that info came out.

Here's the quote we had:

"The BT1 platform is a variant of the T1 body-on-frame platform. The “B” in the name stands for “battery”. General Motors developed the T1 architecture to accommodate battery electric powertrain configurations, with BT1 being the natural progression of the platform. The architecture is capable of supporting various battery electric powertrain types, including single and dual motor configurations, along with pickup truck and UV body styles."

I always thought this was a bit of a stretch, and that the BT1 only was related to the T1 in that they both utilized a basic closed frame as a base, but again, I'm absolutely not saying I'm not wrong lol. I'd love for the record to be fully corrected, facts are facts.
 

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Discussion Starter · #13 · (Edited)
I believe I've read a statement from Mark Reuss or Duncan Aldred mentioning something about the BT1 being based off the T1. I could be wrong Tom, since this was way back before you joined the forums, but this used to be accepted fact around here back when that info came out.

Here's the quote we had:

"The BT1 platform is a variant of the T1 body-on-frame platform. The “B” in the name stands for “battery”. General Motors developed the T1 architecture to accommodate battery electric powertrain configurations, with BT1 being the natural progression of the platform. The architecture is capable of supporting various battery electric powertrain types, including single and dual motor configurations, along with pickup truck and UV body styles."

I always thought this was a bit of a stretch, and that the BT1 only was related to the T1 in that they both utilized a basic closed frame as a base, but again, I'm absolutely not saying I'm not wrong lol. I'd love for the record to be fully corrected, facts are facts.
Ya, this is why I am so passionate about this, there is so much misinformation circulating about the Hummer EV structure, mostly from people who do not understand vehicle structure to begin with. I have read things from

1. Its a modified T1 BOF (nope, that is what Ford is doing with the F150 Lightning)
2. Its a unibody cab and bed mounted on a frame (nope)

I mean look at the photos of the structure, they do not lie. I can tell GM did their homework to make this truck the best performing and strongest in class, and with frameless doors and removable roof it better be stiff or we will have problems down the line. I have no concern, GM has a good structures engineering department and their talents with FEA software is best in class.

The battery pack enclosure likely adds to the stiffness of the struck, but it is not a critical structural component, meaning if you take the battery pack out the chassis does not sag in the middle. There is a box structure that surrounds the battery pack, in the photos that looks beefy.

Mark Reuss called it a unibody in the presser after the SUV reveal, and then corrected himself calling it an "integrated body and structure".

In this post, the only thing I gave that was opinion is that the Silverado EV will ride on the same backbone which I am nearly certain will happen, as the cost for the equipment to build this unibody is too much to amortize over 10-15K Hummers a year. If the Silverado did not give this platform scale the Hummer would certainly have been BOF as it is cheaper to tool up for.
 

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Discussion Starter · #14 ·
I believe I've read a statement from Mark Reuss or Duncan Aldred mentioning something about the BT1 being based off the T1. I could be wrong Tom, since this was way back before you joined the forums, but this used to be accepted fact around here back when that info came out.

Here's the quote we had:

"The BT1 platform is a variant of the T1 body-on-frame platform. The “B” in the name stands for “battery”. General Motors developed the T1 architecture to accommodate battery electric powertrain configurations, with BT1 being the natural progression of the platform. The architecture is capable of supporting various battery electric powertrain types, including single and dual motor configurations, along with pickup truck and UV body styles."

I always thought this was a bit of a stretch, and that the BT1 only was related to the T1 in that they both utilized a basic closed frame as a base, but again, I'm absolutely not saying I'm not wrong lol. I'd love for the record to be fully corrected, facts are facts.
 

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Discussion Starter · #15 ·
For me, I typically think of a unibody as having the suspension parts directly mounted to the body, not to a separate frame. There are two pictures of the new EV platforms on the GM web site, one for the BEV 3 platform, and the other for the BT1 platform. There is a difference that is quite clear between these:

View attachment 866
I was thinking about your comment here over the weekend, and then though, how are other companies doing their EV unibodies when it comes to front and rear cradles carrying the drive unit and suspensions, and low and behold, most everyone is doing exactly the same as the Hummer Ev, even on their unibody car based EV's, here are a couple examples of large global platforms from VW and Hyundai/Kia, everybody seems to be using similar strategy, I think mainly for reparability, and also final assembly plant efficiency.
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Then I was thinking more about it, how does GM do the Camaro? Same type of unibody with bolt in cradles front and rear!
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How about the Bolt EV? Pretty much the same structural design albeit much more lightweight.

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Now for a real body on Frame EV, we look at BMW i3, this is what Body on Frame looks like... Composite body bolted onto an Aluminum Frame



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There was an interview with Al Oppenheiser in Automotive Engineering magazine that I thought may help. It had a short question on the Hummer SUVs construction and materials. To quote Al’s answer: “We have a mixed materials strategy…we took an advanced technology within GM - a sandwich type construction. Two rectangular steel plates protect the battery and provide the vehicles torsional rigidity. The battery and that structure are integrated, making the vehicles off road capability superior to a traditional body on frame or even an integrated (unibody) structure,”.

I know Al is on here, so I kind of answered for him using his “words”! Hope he doesn’t mind. :)
 

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Discussion Starter · #17 ·
There was an interview with Al Oppenheiser in Automotive Engineering magazine that I thought may help. It had a short question on the Hummer SUVs construction and materials. To quote Al’s answer: “We have a mixed materials strategy…we took an advanced technology within GM - a sandwich type construction. Two rectangular steel plates protect the battery and provide the vehicles torsional rigidity. The battery and that structure are integrated, making the vehicles off road capability superior to a traditional body on frame or even an integrated (unibody) structure,”.

I know Al is on here, so I kind of answered for him using his “words”! Hope he doesn’t mind. :)
Thanks for the thought filled reply... Do you know what makes a unibody a unibody by definition? If the chassis structure and body structure are combined with the floor pan to create one structure that shares loads, that is a unibody. I understand that the Hummer structure is not some cheap and cheesy structure like an economy car. The Hummer Ev does have heavy steel components around the battery, but the loads also transfer through the floorpan, and body structure, which get us to unibody by definition. GM officially calls the Hummer EV an integrated body and structure which we can see in the photos it indeed is. You do realize in the definition of a unibody it says (fully integrated body and structure) as an example? In another comment here @azbill mentions that if a vehicle has front and rear subframes that is not (in his opinion) a unibody, but actually it is. Here are the definitions of both a "unibody" and "subframe" for you to decipher and come to your own conclusion? I am not posting this to argue, or be controversial, but more so people understand the terms and structure they are talking about.

The terms "unibody" and "unit-body" are short for "unitized body", "unitary construction", or alternatively (fully) integrated body and frame/chassis. It is defined as:
A type of body/frame construction in which the body of the vehicle, its floor plan and chassis form a single structure. Such a design is generally lighter and more rigid than a vehicle having a separate body and frame.
A subframe is a distinct structural frame component, to reinforce or complement a particular section of a vehicle's structure. Typically attached to a unibody or a monocoque, the rigid subframe can handle great forces from engine and drive-train, and can transfer them evenly to a wide area of relatively thin sheet metal of a unitized body shell. Subframes are often found at the front or rear end of cars and are used to attach the suspension to the vehicle. A subframe may also contain the engine and transmission. It is normally of pressed or box steel construction, but may be tubular and/or other material.
 

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Thanks for the thought filled reply... Do you know what makes a unibody a unibody by definition? If the chassis structure and body structure are combined with the floor pan to create one structure that shares loads, that is a unibody. I understand that the Hummer structure is not some cheap and cheesy structure like an economy car. The Hummer Ev does have heavy steel components around the battery, but the loads also transfer through the floorpan, and body structure, which get us to unibody by definition. GM officially calls the Hummer EV an integrated body and structure which we can see in the photos it indeed is. You do realize in the definition of a unibody it says (fully integrated body and structure) as an example? In another comment here @azbill mentions that if a vehicle has front and rear subframes that is not (in his opinion) a unibody, but actually it is. Here are the definitions of both a "unibody" and "subframe" for you to decipher and come to your own conclusion? I am not posting this to argue, or be controversial, but more so people understand the terms and structure they are talking about.

The terms "unibody" and "unit-body" are short for "unitized body", "unitary construction", or alternatively (fully) integrated body and frame/chassis. It is defined as:


A subframe is a distinct structural frame component, to reinforce or complement a particular section of a vehicle's structure. Typically attached to a unibody or a monocoque, the rigid subframe can handle great forces from engine and drive-train, and can transfer them evenly to a wide area of relatively thin sheet metal of a unitized body shell. Subframes are often found at the front or rear end of cars and are used to attach the suspension to the vehicle. A subframe may also contain the engine and transmission. It is normally of pressed or box steel construction, but may be tubular and/or other material.
Wish I could help further on this subject - my background relates more to designing parking structures than vehicle “structures”!
 

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Discussion Starter · #19 ·
Wish I could help further on this subject - my background relates more to designing parking structures than vehicle “structures”!
I think the debate on this topic centers around peoples perception that Unibody is somehow weak or a negative (GM even seems to not want to call Hummer a unibody instead calling it an "integrated body and structure"), when actually all unibody means is that the frame structure, and body structure are designed to share loads, and be built and function as a single structure (its really nothing to be ashamed of), rather than multiple separate structures being bolted together like a traditional pickup truck is, where it has a cab structure, and box structure bolted to a steel frame which carries the powertrain and suspension.

OK, parking structures, are you a structural engineer?
 

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Discussion Starter · #20 ·
I think the debate on this topic centers around peoples perception that Unibody is somehow weak or a negative (GM even seems to not want to call Hummer a unibody instead calling it an "integrated body and structure"), when actually all unibody means is that the frame structure, and body structure are designed to share loads, and be built and function as a single structure (its really nothing to be ashamed of), rather than multiple separate structures being bolted together like a traditional pickup truck is, where it has a cab structure, and box structure bolted to a steel frame which carries the powertrain and suspension.

OK, parking structures, are you a structural engineer?
Not wanting to beat a dead horse, but I was browsing the GMC website, and it seems GMC has added clarification about the Hummer structure in a highlighted section. They still are not using the word Unibody, but here is what they say Officially...

BODY-FRAME-INTEGRAL ELECTRIC OFF-ROAD TRUCK
An all-new structure eliminates conventional frame rails
, which would raise the center of gravity, and makes the battery pack a fundamental structural element of the chassis. It is protected by sturdy shear panels above and below the double stacked batteries, while an exceptionally rigid floor above the battery pack helps the body resist twisting, even with the Sky Panels of the Infinity Roof removed.

 
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