Automotive History: The Secrets Of The 1960 Chrysler Unibodies Revealed, Thanks To This “Remodel” Of A 1964 Dodge 880 Into A 1959 Dodge Custom Royal

1964 Dodge 880 (bottom) remodeled into 1959 Dodge Custom Royal (top)

For me, CC has been a vehicle for self-education, to bust long-held myths that seemed ripe for doing so, and to solve some longstanding mysteries. It never fails to surprise me how many of these myths and mysteries have been perpetuated so vociferously, since they simply don’t stand up to logic or evidence. One of the bigger myths that I’ve had the pleasure to pop is the “garden party” story about why Chrysler downsized the 1962 Dodge and Plymouth.

A related mystery is the one about the conversion of Chrysler’s full-size 1960 cars to unibody construction. It’s a subject that has been debated in the comments here at CC since its earliest days: Were these 1960s “all new” that just happened by coincidence to look a lot like their predecessors, or were they extensively “remodeled” 1957-1959 cars? Thanks to a commenter, we now have the story and pictures of how one person remodeled a unibody 1964 Dodge 880 convertible  into a 1959 Dodge Custom Royal. It solves the mystery quite compellingly.

The irony is that I knew the truth a very long time ago, as a kid. It was all too obvious to me that this 1961 Chrysler 300 (bottom) was anything but an “all new” car in relation to its 1957 predecessor (top). Nobody in their right mind decides to start designing an all new car from scratch and ends up making it look so much like its predecessor, right down to so many details. Sure, there were external sheet metal differences, but those were easy to change. What was obvious to me then as an eight year old was that key hard points, that define the critical overall shape, as well as key elements, like the shape of the windshield, how the doors relate to the body (and windshield), the wheel openings, how the “greenhouse relates to the lower body, etc.”.

Before we plunge in let’s first define the semantics:

An “all-new” car (or body) is one that’s started with a clean sheet, meaning nothing is based on the predecessor. This is driven by the desire to have new basic proportions and design, as well as significant changes to the underlying technology, such as new suspension systems, frames/body structure, and other key elements. Some examples of that are the 1955 and 1965 Chevrolet (and related GM A/B/C Bodies), the 1965 Ford and the 1957 Chrysler Corp cars, with their drastically new body proportions and new torsion bar front suspensions.

A “remodeled” car, like a remodeled house, means that the predecessor car is taken as the starting point, and changes are made as required (but only as required) to attain a specific goal. This invariably means that certain key hard points and proportions will be maintained, as well as whatever other chassis, suspension and other components that can be. This is obviously a significantly lower cost process than a clean sheet approach, as some/many components and much tooling can be modified and/or reused, as it’s cheaper to modify them to the degree necessary than to create all-new ones.

There are articles out there that cover the transition to the 1960 unibodies, but they do not describe either the initial scope of the project or the process itself. The fact that the resulting unibodies look so obviously similar (except for surface styling changes) would suggest that some consideration of the process might be worth some research or at least even logical speculation, but I’ve yet to find any.


It’s always best to start from the beginning, to ascertain why a certain project was undertaken in the first place. In the case of the 1960 Chrysler unibodies, it starts with the frame underneath their predecessors. That 1957 frame (top), is essentially the same in its basic design and configuration as its predecessors (1956 and earlier, bottom), which actually dates right back to 1949 in its basic design and configuration. It’s an old school design, with the main frame rails running straight under the passenger compartment. It’s a clear indication of the kind of cost pressures Chrysler was under in developing these 1957s.

There was a significant problem with reusing that old frame design: the 1957 Chryslers were a good ten inches lower than the 1949s, and six inches lower than the 1956s. The result was a serious loss of leg room and head room.

It’s not as good as climbing into one, but this picture does show the issue: the floor is high up on the frame, level with the sill. And out of necessity, the seats are quite low in relation to the floor. Front seat passengers were able to stretch out their legs out horizontally, but rear seat passengers were short-changed. Headroom was compromised all-round. This was the bitter price to pay for longer, lower, wider. Suddenly 1960 didn’t look so hot, especially if you had to sit in the back.

Ford and GM had addressed this issue with their new lower 1957-1958 cars more progressively. Ford’s “cowbelly” frame bulged out at the sides, making room for footwells for the rear seat passengers. Not as good as a genuine perimeter frame—which replaced it in 1965—but it was better than Chrysler’s old school frame.

GM’s new X-Frame addressed the issue in a different way: By strengthening the sills and adding lateral ribs to the floor pans, it was able to eliminate the side rails altogether, opening space for foot wells.In essence, the X-Frame was something of a half-step towards a unibody, by making the body a much more critical part of the combined structure, in terms of its overall strenght and rigidity.

By 1961, GM started moving to the perimeter frames (at Olds), the ultimate solution to BOF construction. Perimeter frames require the body to play an even greater role in the overall rigidity of the combined structure, as the rather small frame members provide limited amount of strength and rigidity by itself. Significantly, it allows a lower floor at both the front and rear.

Meanwhile, the increasingly popular unibody Ramblers had none of these issues, resulting in the best interior space utilization.

Ford and GM’s new frames and Rambler’s unibody resulting in improved interior room left Chrysler at a decided disadvantage. This is precisely what led them to the key element of the 1960 program: to rid the underbody of that massive frame.

That’s a key issue of this program (eliminating the frame under the body), because in reality, these are not true or full unibodies, because the whole front one-third of the car is essentially the same as before, retaining a shortened frame (subframe), which was bolted to the back two-thirds of the body. The most crucial changes were to the sills, the cowl structure, which provides critical torsional rigidity, and the door pillars.

This picture shows how the unibodys (bottom) had a much thicker and less curved A-pillar structure to provide critical strength to the roof. This did result in a somewhat smaller door opening, but that was partially offset by the doors having a wider swing.

Here’s a cross section that purports to show the improvements in interior space utilization. The seats could now be mounted a bit lower, improving headroom. And leg room is significantly improved in the rear seat, thanks to a lower floor height.

What Chrysler did with the large cars in 1960, “remodeling” the back two-thirds into unibodies but retaining the front frame and clip is a key distinction from the true unibody that Chrysler was developing for the 1960 Valiant (top) and a similar structure it would use for the new downsized 1962 Dodge and Plymouth (bottom). In these cars, the front inner fender structure that supports the suspension, steering and the engine are a critical integral element of their bodies as there’s no subframe.

The whole front third (from the cowl/firewall forward) of the large 1960 Chryslers was essentially unchanged. That’s a huge savings, and a key aspect of this whole program, whose primary purpose was to increase interior space, along with the potential for a more rigid body structure to improve handling and reduce squeaks and such.


This is where the featured cars come in, from an article at The owner/builder, Scott Steers, had long wanted a car that he developed a crush for when he was five years old: a brand new pink 1959 Dodge convertible. Since he had motorless 1959 Dodge sedan and some other sedan parts, and was able to pick up a ’64 Dodge 880 convertible for a good price, he decided to build his own, a clone of the real thing (note: the pictured 1964 880 is not the actual car used in the conversion)

Scott: “The two cars wound up being parked next to each other by chance where I store some cars and it was only looking at them side by side, I started to realize how similar they were. I started using a tape measure and made paper patterns of various curves and came to realize that they were practically twins”.

Let’s start at the front end, since this was such a key element: would the front clip of the ’59 fit the unibody ’64? Why yes, it did! Although it took a bit of doing, in terms of changing to the hinges mounting and various other mounting tabs and such. This was because the cowl, the single most important structural element on a unibody, had to be modified and strengthened considerably. But the basic dimensions and shape were similar enough for the ’59 front clip to mate to the ’64 body without any serious surgery.

Surprisingly, the front bumper bolted up in the correct position without any modifications”.

This confirms that the front subframe was essentially the same as the front portion of the old frame.

“With the upper fenders in position I welded the lower part of the 64 fenders into place. I had to do a little hammer and Dolly work on the front edge to get the contours to match up but nothing too bad”.

Here’s the rear end under reconstruction:

“Taking measurements off of my ‘59 Coupe, I put the quarter panels in the proper position holding them in place with sheet metal screws and when I was happy with the location, I modified the 880 trunk hinges to hold the ‘59 deck lid to where it matched up with the rear quarters”.

“I butt welded the vertical seams and used panel bond on the horizontal seam with a one-inch overlap held together with sheet metal screws while it cured. This seam would lay under the stainless-steel body molding and would not be visible. I had to modify the rear bumper brackets to put the bumper in the correct position”.

“Lower rear quarter panel contours were the same on both cars and matched up nicely where I butt welded them together. The spot weld flange on the bottom matched up to the 1964 trunk extensions perfectly. Inside on the lower edge of the trunk floor everything matched up as well. The panels all fit like they were made for the car. They certainly did not change very much when they went to unibody in 1960!”  True that! Certainly in places where structural strength was not critical, like the rear/trunk portions of the body other than the new stiffer floor panels.

Here’s the final product, although Scott may make some more changes to the interior. As to driving it, and comparing the unibody to a BOF ’59 Dodge, here’s what he had to say:

“The ‘57 and up frame Mopars were pretty good to begin with, probably the best handling of the full framed American cars. I would say that the unibody cars feel a little lighter and you sit a little lower. Definitely a little bit of a more modern feel in the steering, but they are still big American land yachts”.

This was obviously not just a simple bolt-on job; a fair bit of body work was involved. But it’s also quite clear that the changes Chrysler made were functional (except for exterior styling sheet metal changes), and not as extensive as might be expected, which made this conversion feasible.

The question as to why Chrysler undertook this “remodeling” instead of creating all-new unibody cars for 1960 is easy to answer. The collapse of its sales in 1958 and resulting losses created an existential crisis for Chrysler. It had been operating under the assumption as if it was still #2 in the market, or could be again. The 1957 program was a huge investment to make that happen, and it failed miserably, due to the change in the market away from large cars in 1958 and the poor quality of the ’57s.

Chrysler began a series of massive staff cutbacks in 1958, affecting the ranks of its white collar staff across all departments. At the same time, it committed to building the compact Valiant for 1960, a very demanding project. Funding an all-new big car program for 1960 was out of the question. And as put forth in my article on the downsized 1962 cars, Chrysler’s response to the failure of the ’57s was to give the engineers more power over the designers.

The same factors that were at work in the limited 1960 full size program were precisely what also led to the cancellation of the very ambitious new full-sized program envisioned for 1962, resulting in the downsized Plymouth and Dodge and a restyle for the large Chryslers.

The conversion of the large cars to partial unibodies was clearly very much an engineering-driven decision, as the styling for 1960 was then by necessity not much more than a refresh, as the basic proportions and many hard points had to be kept.

The marketing emphasis for 1960 was on the solidity of the new unibody cars and not on their styling, which certainly didn’t look all that dramatically different from 1957. Suddenly it’s 1960…again.

In summation, I realize that much of this debate boils down to semantics. Are there any parts in the 1960 bodies that are the same as in a ’59? I don’t know if we’ll ever have a definitive answer. I’ve read anecdotal reports that say yes, but they might well be quite minor ones, especially in non key structural areas. There was obviously every incentive to reuse anything that could be.

But the key issue was the process, which involved starting with a ’59 body and making the structural changes as required. The result is evidenced in Scott’s conversion of a ’64 into a ’59 clone: It was not that difficult, and a surprising number of parts fit readily enough.

In any case, the rear two-thirds of a body hardly make “a new car”. What’s indisputable is that the front one-third is essentially the same, except for exterior sheet metal changes for styling purposes. In addition to some likely inner body parts or assemblies, most critically, this allowed reuse of a significant portion of chassis/suspension components as well as the drive train.


Related reading:

1962 Dodge and Plymouth: The Real Reason They Were Downsized A ’64 Dodge 880 Transformed Into A ’59 Dodge Royal