I decided to finally resolve an issue that I first wondered about as a kid: did the new for-1956 Cadillac 4-door hardtop use the same roof pressing as the existing 2-door hardtop? It wasn’t as quick and easy as I initially expecte. The big challenge was finding two shots from as close to the same angle as possible.
I know there are some purists here who are offended by the term “four door coupe”, but these 1956 four door hardtops were essentially a four door version of the existing two door hardtop coupes. Essentially, or actually? Did the four door use the exact same roof as the two door?
Don’t let the bright trim molding on the lower edge of the two-door roof throw you; it was applied to the roof, so the real lower edge is at the bottom of that, as you can see at the top of the front side vent window.
Taking measurements on two different images is precarious, even if they appear perfectly lined up well like these two. Eeven the slightest difference in camera angle and lens type can cause subtle but surprising distortions. I wasted too much time trying that approach until I found the obvious and definitive answer to the question. I’m sure some of you will too.
Purely as a frame of reference, here’s the sedan version, which of course has a totally different roof as well as a shorter tail. The hardtop roof is also lower, by over two inches. It certainly changes the visual impact considerably.
Update: Since this is a bit obscure, I won’t keep you in suspense any longer. Here’s what I found:
click on image for larger view
As I said, I was stumped for a while. Using my architect’s ruler, I kept getting very slightly mixed messages. Logic dictated that given how close those results were, it made huge amount of sense that this would be the same roof on both.
But then I looked at the gap between the rear edge of the roof and the trunk opening. Aha! There’s no doubt that it was longer on the 2-door hardtop. Not much, maybe a couple of inches at most. Why GM though that small difference was worth tooling up a different roof for is a question whose answer has long been lost to the sands of time.
This can be confirmed by running a vertical line from the back edge of the roof. On the 2-door, it clearly ends a bit more forward on the wheel cover than on the 4-door.
But at least I can stop wondering.
Always interesting you are Paul. The “obvious” answer……. A good breakfast puzzle. You can go with hard datum points like WB and length and check for distortion in each picture and account for that . IE “measure” the ratio of WB and length for both and compare to actual..give you some idea of distortion. If by luck they are within a percent or 2 you could overlay. Looking closely at that picture it does appear that the pictures Were taken With a very similar lens set ups and distances based upon the foreshortening of the rear of the car . if you had a catalog u could see if the cars shared say a headliner or window strip part.
I don’t know if they’re the same roof, but they sure look like the same roof, to the point that, if they’re not, one would wonder why GM would go to the expense of creating a different roof that looked so much like another.
I would imagine the only way to definitively know is by finding a 1956 Cadillac parts catalog and compare roof sheetmetal part numbers.
Maybe not so obvious! The only obvious answer to me would be to find ones in the real world and take a tape measure to them. Or find a contemporary parts listing. I went so far as to look at the vehicle information kit for the 56 Caddy at the GM Heritage Center. No smoking gun as to if they use the same body panel, but they have the exact same windshield, backlight and side window glass surface areas. The vehicle height differs by 0.1inch, not sure it that is due to body or suspension difference. rear seat dimensions differ slightly.
I think they are the same panel, as Rudiger says, why would they have different parts that look identical to the naked eye? But we are talking about GM here…
¨I wasted too much time trying that approach until I found the obvious and definitive answer to the question.¨
Please do not keep us in suspense any longer. What is the obvious answer?
I’ve updated the post with the answer and proof of how I got there.
Everything looks different between the 4-door sedan and the 4-door hardtop, which makes sense since you said the tail is shorter on the sedan. The hardtop rear door looks longer, the side trim looks as if it’s located farther back on the rear door of the sedan, and even the quarter panel “rocket” looks longer on the sedan to make up for the shorter door (reference it to the rear wheel). It appears to be a different length again on the two-door hardtop.
I’d say the 4-door hardtop is basically a two-door hardtop with different doors (and quarter panels), making the roof the same, but I have no idea.
The comparison photos of the hardtops seem to clinch the case that the roofs are identical. It would also make sense considering that the ’56 4-door hardtop was a one-year design, given the ’57 Cadillacs would sport all-new bodies.
But GM was flush with cash back in those days, so there very well could be subtle differences.
I looked in GM parts Wiki online, but no Cadillac catalogue that early, unfortunately.
Presumably, the Buick Roadmaster and Olds 98 shared the hardtop roof, but you’d think they would have made the Coupe’s a little longer in ’54 and saved some money.
I’m curious as to why the sedan has that front roof overhang. I remember driving our ’56 Olds hardtop 4 door (roof same shape as Cadillac’s), and if you pulled up too close, you had to lean forward and twist your neck to see the stoplight. Dad bought a lens on a suction cup to stick on the windshield.
The rear seat was easier to get into than it looks because of the height.
When GM began making large pillared sedans again in the late 60’s, they had about 2 inches more rear legroom than the hardtops on the same wheelbase. More headroom too. Yet they dropped them from the C bodies again in ’71, because they weren’t popular.
Dad bought a lens on a suction cup to stick on the windshield.
Ah, “Traffic Light Viewer”. It’s been a while since I saw them in the vehicles.
I think this accessory is perfect for Germans to install in their vehicles. The traffic lights are positioned at the stop lane instead of across the intersection (as in the US). This forces lot fo drivers to stretch their necks forward to see the traffic lights.
It would certainly be interesting to see one of these “undressed” so as to take measurements and look at the different weld marks.
On the other hand, it looks like they wanted the spear leading to the rear bumper (new for 1956) to be the length it is on the two door hardtop. Making it that long on either four door model would have meant a different rear door from a 1955, and the 1955 door was already different from on the original 1954 model. By making it shorter and not overlap onto the rear doors they could keep the 1955 door. They probably also thought it would have to be even longer on the four door because the two door length would only overlap onto the door a too short amount.
In high school a friend had her own 1955 two door hardtop (light green/white roof) her father had redone, which at that point was a car from a different age plus a highly unusual type of car to drive to school and cruise around town in. But we did. Maybe the Hydramatic was a little off, but it could chirp the tires on a 1-2 shift.
I love these cars, such a beautiful beast. I finally got mine, sold it a couple of years later. It felt like driving one of those old school buses. I had a four door hardtop ’57 also. The flatter hood and fenders made it feel more modern than the ’56. Any ’50s or ’60’s GM four door hardtop makes for a cool cruiser. I don’t know how good the side impact protection would be, not too good I’d guess.
Coupe means cut and refers to a lower roof line not number of doors. Rear glass looks very different.
The roofs on the two and four door hardtops look the same but the rear sections of the bodies are different,
Not surprisingly, it’s the exact opposite of that.
The backlight slope angles are different. (see GM Heritage Center)
Nomenclature – Panel in front of bootlid is “Dutchman’s Panel”.
Because it has tulips (two lips, one to hold the window gasket and one to hold the trunklid gasket). “Tulip panel” is also used.
It does remind me of how the 1961-64s used the same roof for the C-body 2 door hardtops and the B-body 4 door HTs. I think…
If you like this kind of thing the guy at Car Style Critic
posts a lot of similar stuff. For example he did a post on how the ’53-54 Chevy/Pontiac (A body) greenhouse was recycling the 1952 Oldsmobile (B body) one with minor adjustments. Fooled little kid me.
I was flummoxed by this, my Photoshop ruler wasn’t giving me anything I could reliably go off of. Leave it to 50s GM to tool up 2 different stampings. That’s a head-shaker of Halberstam’s The Reckoning level.
I never noticed this. Fascinating. The sedan photo reminds me how much GM set the stage for 4-door sedans vs. 4-door hardtops, as Ford and all the Chrysler brands would go to six-window designs in 1957.
I am not an expert, and I have no inside info.
I look at the two vehicles you’ve marked with the red lines, and what I’m seeing is a subtle difference in camera angle. This is noticeable in the “wing” windows. The rear of the driver’s side wing window is behind the front edge of the passenger side wing window, on the “green” car. The rear of the driver’s side wing window is even with the front edge of the passenger wing on the “blue” car. The “green” car camera is slightly forward of the “blue” car camera, as are the red lines drawn on the respective vehicles.
Given the slight difference in camera angle, and the curvature of the bottom edge of the rear window, I think the red lines drawn on the photos are mis-placed. I lean towards them having the same roof.
What I’m having trouble with, is that the wing windows themselves seem to be larger on the blue car.
The difference in camera angles in these two shots is remarkably minimal. But in any case, the key clue, which I pointed out in the post, is not dependent on camera angle. The space between where the roof meets the rear deck and the front of the trunk opening is very clearly larger in the 2 door. That is the smoking gun.
Schurkey, about wing window height…
The 2dr hardtop uses a “flipper” door seal at the top of the glass. Flipper -well- “flips” down over top of glass about an inch or so. To give the flipper continuity in appearance, flipper-size trim follows the roofline below the “gutter” to wrap below the back glass. A second piece trims the gutter and terminates at the beltline.
The 4dr hardtop does not use a flipper seal, thus no need for matching trim. Instead the 4-door’s gutter trim (located above glass, making wing appear taller) takes a different path to wrap below the back glass, instead of terminating at the beltline.
As mentioned by others, the parts book would have numbers for roof’s skin, side-rails, etc. I’ll add that 2dr and 4dr hardtop (no post, the green and blue cars) use the same decklid; sedan (post, the pink car) does not share the decklid. Back glass (backlight) interchange follows the same pattern.
Now we just need to find someone with a late-50s Hollander manual!
It’d be interesting to know if the 4-door’s “gutter trim” and the 2-door’s “flipper trim” end up “morphing” to the same trim/line below the rear glass?
Here’s a view with flipper up.
Is the drivers door on the 2dr HT longer than the one on the 4dr HT? Looks to me like it is.
Yes, significantly longer.
Isn’t that almost invariably the case? Maybe we should do a post on finding cars that have the same front doors for both 2 and 4 door versions.
Morris Marina sedan and coupe. What do I win? 😉
Rear legroom in the SdV is 1.6 inches longer than CdV and rear headroom is a bit greater. Perhaps that helps answer the roof question.