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X-Frame

X-Frame History - help

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An X is an X except when it isn't an X… have you met one of my X's? :D

Seriously folks, a colleague and myself are putting together information for a book about the history of the automobile X-Frame chassis (hence my user ID).

In a broad stroke generality, American cars built between 1932 until about 1965 were built with one form of X frame or another and they were often configurations almost looking like other letters and called many different things.

We have found the world's first use in a automobile dating back into the early 1920s in France and centering in on the "last" use. In America the last holdouts were the Buick Riviera (until 1970), the Checker (until 1982), and a few specialty cars such as the Delorean which had a more "backbone" X. There were others especially foreign that date later but… I am asking for those who may want to chime in on if they know of the "last" use of an X in any vehicle rather it be automobile, SUV, truck, or military?

I recently saw "Spiderman 3" which has a scene of some AM General Humvee's overturned and we can see the chassis of one but it clearly had an X frame… but Humvee's don't have an X - or do they (one model or another?) Or was this only a computer generated fantasy car and not accurately depicting a real vehicle? And why would they have chosen an X frame configuration that looks similar to the mid 1950s Chrysler convertible frame?

Comments?

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I think you are confusing X or K shaped center crossmembers, which are very common, with the late 50s GM X frame. Nearly all automobile frames, from the beginning until the present (trucks, mostly), use a variation of the ladder frame. I could be wrong, but I have never seen a 30s through early 50s American car with a true X frame, certainly none of the Big 3

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I think you are confusing X or K shaped center crossmembers, which are very common, with the late 50s GM X frame. Nearly all automobile frames, from the beginning until the present (trucks, mostly), use a variation of the ladder frame. I could be wrong, but I have never seen a 30s through early 50s American car with a true X frame, certainly none of the Big 3

I am afraid you are incorrect. I can point you to hundreds of examples but just for one here is a 1934 Buick chassis and will note they even call it an X brace...

post-68778-143138806708_thumb.jpg

post-68778-143138806713_thumb.jpg

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I think you are confusing X or K shaped center crossmembers, which are very common, with the late 50s GM X frame. Nearly all automobile frames, from the beginning until the present (trucks, mostly), use a variation of the ladder frame. I could be wrong, but I have never seen a 30s through early 50s American car with a true X frame, certainly none of the Big 3

The frame of my '33 Plymouth has an X shaped center piece and the sales literature mentions it as a "X Frame". Does that count as a "30s through early 50s American car with true X frame"? Or is a "true X frame" something different. Here is another person's '33 Plymouth chassis where you can see the X:

db20021028-01.jpg

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The frame of my '33 Plymouth has an X shaped center piece and the sales literature mentions it as a "X Frame". Does that count as a "30s through early 50s American car with true X frame"? Or is a "true X frame" something different. Here is another person's '33 Plymouth chassis where you can see the X:

David, I am wondering if 58Mustang is confusing X with X-Body style frame? Yes, your 1933 Plymouth is a "true" X-frame. Even the ones for GM starting with the 1957 Cadillac and continuing on with the 1970 Buick Riviera, is also a X frame. It is called a Tubular Center Section X Frame and some call it a Cruciform Frame.

To us a K frame would be like that on the 1959-1960 Buicks and if he is thinking of early 1930's Chevrolet, Pontiac, etc... then those were different and called YK frames. I can list exactly which year each started with true X frames...

Buick - 1933

Cadillac - 1934

Chevrolet had the YK frames in 1934-1935 except the Standard model which had an X in 1935 only then started with X on convertibles in 1941. the 1940 convertible had a unique 1-year only K type.

Oldsmobile - 1933

Pontiac - YK 1934-1936 then X in 1937

And that is just the GM cars.

To elaborate, some of the earliest American cars to have a true X frame were:

Cord 1929-1932 (the 1936-1937 models were unibody design)

Auburn 1931-1936

Hudson, Terraplane, Essex, Nash, Packard and the Studebaker offshoot Rockne all started in 1932 with true X frames.

Chrysler products had X frames starting in 1932 but they are a bit unique to me as they look more like a VC configuration as the two rear legs are short and a bit curved which was short-lived. That would include the 1932 Plymouth, David and the 1933 you have changed to a true X.

Eric

[*NOTE... Correction, seems to be 58Mustang's interpretation of X frame that is a bit skewed. Yes, all of the earlier X frame cars had a ladder type frame with center brace but in lamens terms and those listed by many manufacturers in their materials theses are simply called X-Frames. A ladder frame is normally considered one that has perpendicular cross members in multiple places along the length of the side rails - like a household ladder and used more commonly pre 1932 and post 1964 and normally in trucks]

Edited by X-Frame (see edit history)

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David, I am wondering...

Eric

Actually I'm not David. I just linked to a photo he took. :)

Someplace I probably have an equivalent photo of my car's frame but it isn't available on line at the moment.

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It's always been my understanding that the X shaped crossmember in some frames, although apparently enough early on to be called an "X frame", was of late only considered a type of crossmember and not the defining aspect of the frame. I've always heard "X frame" used to refer to a frame in the shape of an "X" with no side rails, as in the 1958-1964 Chevy ( http://www.xframechevy.com/ ) and many Lotus models.

x-frame-1024x459.jpg

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Actually I'm not David. I just linked to a photo he took. :)

Someplace I probably have an equivalent photo of my car's frame but it isn't available on line at the moment.

No problem.

Now that we have established a baseline interpretation and industry firsts... let's get back to figuring out which were the "last" with this configuration with or without side rails :)

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It's always been my understanding that the X shped crossmember, although apparently enough early on to be called an "X frame", was of late only considered a crossmember. I've always heard "X frame" used to refer to a frame in the shape of an "X" with no side rails, as in the 1958-1964 Chevy ( http://www.xframechevy.com/ ) and many Lotus models.

I can see your confusion and with what we are doing is trying to explain these various interpretations that have come along. In genral, if it has a X center brace then it is considered a X-Frame - with or without side rails. There are a lot of variations out there like the Lotus example you gave. The rare 1967-1970 Toyota 2000GT frame is almost exactly like the Lotus and this variation of the X frame is called a "backbone" X.

The one you gave above for GM cars is the tubular center section X frame and I even spoke with its designer a couple years back. He was in his 80s but told me some background about it. US Patents are also on some of these various designs and again, referenced as X Frames but like 58Mustang eludes to sometimes referred as X-Braced. The 'X' is the key for ALL of them. Are you confused yet? :confused: The history and sorting out the designs and how it was part of automotive history will be explained in our book.

BUT... still asking anyone for examples of "last" ones like these.

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It's always been my understanding that the X shaped crossmember in some frames, although apparently enough early on to be called an "X frame", was of late only considered a type of crossmember and not the defining aspect of the frame. I've always heard "X frame" used to refer to a frame in the shape of an "X" with no side rails, as in the 1958-1964 Chevy ( http://www.xframechevy.com/ ) and many Lotus models.

x-frame-1024x459.jpg

________________________________________________________________________

My belief too Dave, A true X with no side bracing. 1958-64 Chevy and 1958-60 Pontiac's.

The reason I say a true X is because the X alone frame above is the whole unit, where as the picture in the #3 thread the X is just the adjunct to the the main perimeter frame...It's merely for rigidity bracing . This is also self evident because the X is drilled or stamped full of holes, meaning it's not there to carry weight.

D.

Edited by helfen (see edit history)

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Maybe my word "true" is throwing people off here? When I say TRUE I am meaning that the center section is shaped in a X configuration and not a K or YK or other configuration.

>-<

___

><

>|<

>C

This means with or without side rails.

We have been studying this for years and this is how we are going to present it especially when the manufacturers at the time also indicated the same. Yours is only one belief and we will try to embrace yet dispel some of them.

Edited by X-Frame (see edit history)

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I am afraid you are incorrect. I can point you to hundreds of examples but just for one here is a 1934 Buick chassis and will note they even call it an X brace...
I am afraid that I am, very much, correct. The picture that you have posted is a ladder type frame with an X shaped crossmember, not an X frame. The picture that Dave Moon posted is an X frame. The terms, X brace or X member do not equal an X frame. Please point me to hundreds of examples of true, pre 1958, X frames, that is, a frame that does not have full length side rails and is a true X shape. I will cue up the theme from "Jeopardy"

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It's always been my understanding that the X shaped crossmember in some frames, although apparently enough early on to be called an "X frame", was of late only considered a type of crossmember and not the defining aspect of the frame. I've always heard "X frame" used to refer to a frame in the shape of an "X" with no side rails, as in the 1958-1964 Chevy ( http://www.xframechevy.com/ ) and many Lotus models.

Being ignorant of cars of the 50s and 60s, your image has now explained to me some of the comments about the '59 Chevy crash test video that was floating around a while ago. I couldn't understand why a X frame could be weaker in a front offset crash than a conventional ladder frame. Of course I was visualizing an X frame as implemented in my '33 Plymouth which has full length side rails, not a frame like your image shows. I can see now how that frame structure could be inadequate for dealing with such a collision.

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I am afraid that I am, very much, correct. The picture that you have posted is a ladder type frame with an X shaped crossmember, not an X frame. The picture that Dave Moon posted is an X frame. The terms, X brace or X member do not equal an X frame. Please point me to hundreds of examples of true, pre 1958, X frames, that is, a frame that does not have full length side rails and is a true X shape. I will cue up the theme from "Jeopardy"

Sorry, you are only one person with one belief and can't see the big picture of what I am saying. You have to be more open minded. I can and will post some examples a little later per the manufacturer's descriptions. There are dozens of variable design X frames out there and X-Frames is the catagory :) But then again I guess you will question even the maker's descriptions huh???

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Sorry, you are only one person with one belief and can't see the big picture of what I am saying. You have to be more open minded. I can and will post some examples a little later per the manufacturer's descriptions. There are dozens of variable design X frames out there and X-Frames is the catagory :) But then again I guess you will question even the maker's descriptions huh???

__________________________________________________________________________

A true X frame stands alone with NO other support.;)

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When you say "X Frame", most car guys, immediately, think of the 58 and later GM X Frame. In 32, Ford began using a "K" shaped crossmember, yet I have never heard them called "K Frames". If you look at any road tests of early cars, in the specs, you will see most as having ladder frame construction. The use of the term "X Frame" as a broad brush term is incorrect. It is not an industry standard term. All automatic transmissions are not Hydomatics. Sure, Plymouth may have touted it's all new X Frame and all of it's benefits, but guess what?, Floating Power doesn't really float. When you can show me "X Frame" as a term and description that has a specific definition that is recognized and used by auto engineers as a whole, I will deign to your newly minted term

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I agree with 58Mustang, only true no side rails should be considered X frames, in my opinion. But this is all "unofficial", and perhaps marketing. Does anyone know what the SAE has to say about this subject, or do they not address it?

And, by the way, I have one of each true example, ladder and X. Is there anything like a true x with side rails and no perpendicular "rungs" whatsoever?

John

Edited by jscheib (see edit history)

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I can see now how that frame structure could be inadequate for dealing with such a collision.

I'm at a loss to think of any collision for which this design would be adequate. :eek:

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I'm at a loss to think of any collision for which this design would be adequate. :eek:

___________________________________________________________________________

Correct Dave. While Chevrolet (1958-1964) and Pontiac (1958-1960) used them, other GM family members did use the X frame but also used side frame rails. Interesting that in 61 Buick went to the X plus finally a open two piece driveshaft and Pontiac went to the perimeter. I remember talk about how good these frames were in regards to strength and how bad the were if you were unfortunate to get in a center punch type of accident-a lot of intrusion to the very center of the car. The 1961 Pontiac's used the new perimeter frame to channel the bodies between the rails and to eliminate the two piece driveshaft of the old X frame and go from a three link rear end to a four link. This also made the cars lower and stronger.

D.

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Thanks West. When a well known publisher agrees then you know there is something to it :)

I first must apologize to 58Mustang for my rants yesterday. When I get started sometimes I don't know when to stop especially in the heat of the moment while talking about something which is a passion… Sorry John.

 

Second, it can be summed up as semantics. Yes, a lot of companies called their chassis X-Braced or X-Membered or even X-Type but you can lump it up as a X-Frame. Heck, I even saw Oldsmobile call their "new and improved" chassis a Dreadnought . But rather than clutter the thread up with examples I want to cite, it would be easier to show you what Cadillac called the "X" you refer to as they were the originators of it in 1957. The chassis was designed for the Eldorado Brougham but at the last minute they used it on the entire Cadillac line. Without giving away too much, GM was aware that they had an issue with the chassis but it was also Fisher Body who wasn't ready either

 

As I mentioned, they call it a "Tubular Center X" Frame and not simply a X Frame.

 

As for a X that has no cross bracing… there isn't one that I know of outside of some patents I have seen. You would need at least some for engine-transmission support. Also, it would not be very stable without it having too much "twist" which is just what the X was originally designed for, torque issues, but you still need the added support of cross members (rungs as you called them). There are some very minimalist frames though with only the needed cross members.

1957 Eldorado Brougham and 1958 Cadillac is below.

Eric

post-68778-143138807959_thumb.jpg

post-68778-143138807962_thumb.jpg

Edited by X-Frame (see edit history)

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When you say "X Frame", most car guys, immediately, think of the 58 and later GM X Frame. In 32, Ford began using a "K" shaped crossmember, yet I have never heard them called "K Frames". If you look at any road tests of early cars, in the specs, you will see most as having ladder frame construction. The use of the term "X Frame" as a broad brush term is incorrect. It is not an industry standard term. All automatic transmissions are not Hydomatics. Sure, Plymouth may have touted it's all new X Frame and all of it's benefits, but guess what?, Floating Power doesn't really float. When you can show me "X Frame" as a term and description that has a specific definition that is recognized and used by auto engineers as a whole, I will deign to your newly minted term

Even these early Fords you speak of will fall into a variance of the X in our book. Though they look like two bows linked in the center rather than straight line X, they still fall within the peremiters of the catagory. Ford started using this in 1933. The 1932 Ford had a ladder frame. Not sure what you are referring to as a K frame in 1932... example please :) If anyone has SAE info to post, please do.

Below is an example of the 1933 Ford frame out of a crazy 3-D brochure they made then but you can see they say it is a X type frame. I double checked and the 1932 is a ladder frame.

Another rare example of an X that I am sure would be disputed sat under the Totota Crown models of the early 1960s. It was massive and looks more like a H but it does bow towards the middle and Toyota calls it a X Frame.

Eric

post-68778-143138807975_thumb.jpg

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I'm at a loss to think of any collision for which this design would be adequate. :eek:

There would be none!

GM's "X" frame first appeared in 1957 on Cadillacs and should not in anyway fashion or form be confused with a ladder frame having "X" or "K" bracing. Candidly in my view it is a perfect example of cheapening a product without regard to anything other than the bottom line. They virtually spawned a whole new service business to bring them into square. Isn't hard to twist one of those suckers by just jacking it up to change a tire. Engineering crap!

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There would be none!

GM's "X" frame first appeared in 1957 on Cadillacs and should not in anyway fashion or form be confused with a ladder frame having "X" or "K" bracing. Candidly in my view it is a perfect example of cheapening a product without regard to anything other than the bottom line. They virtually spawned a whole new service business to bring them into square. Isn't hard to twist one of those suckers by just jacking it up to change a tire. Engineering crap!

You got to remember that the old high profile cars of the 1940s was now outdated and with each new year the manufacturers tried to lower and lower the car's height. To accomplish this they needed to drop the body between the rails and that was next to impossible with a perimiter frame with an X without sacrificing some leg room too. That is only one of the main reasons the 1957 style GM frame was developed. For lower, sleeker, more modern cars of the "jet and space" age. Different mindset then and automobile testing wasn't as complex as it is today. It was more about looks than safety. All GM (except the Buick Riviera) had abandoned this frame by 1965 to a boxed corner perimeter frame more wide open in the center to drop the body as low as they want and for safety reasons.

To be fair, Ford stopped using the X except in Convertibles in 1949 but Lincoln didn't stop until the new 1958 unibody design, Chrysler products stopped around 1941 except for convertibles.

Eric

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