As we learned in our previous installment, 1965 saw a revamp in Cadillac’s lineup: The “Series” naming scheme that began in the Thirties ended as Calais became the entry-level model, all models (excepting Seventy-Five) received stacked quad headlamps for a new visage, and the Eldorado was elevated to Fleetwood Eldorado status. Cadillac also made some engineering changes, in hopes to quiet some pesky customers and lawyers who kept bringing up safety.
General Motors bet on a novel frame idea back in 1957, when it put the X-frame into production on Cadillac vehicles. The frame expanded in usage to Chevrolet and Pontiac in 1958, and finally to full-size Buicks in 1961. As GM’s brands had some independence at the time, Oldsmobile opted out of any X-frame usage.
The X-frame was a tubular steel design, which lacked the traditional side rails of a ladder chassis. This allowed for a lower ride height at a time when long and low was very important. Called the Safety Girder system, the X-frame promised stronger torsional rigidity than a traditional ladder frame.
X-frame vehicles had their rocker panels, crossmembers, and cowl reinforced and integrated into a semi-unitized frame. GM argued that no frame rails were needed, because the reinforced parts worked in tandem to make the body very strong. Notably, there was no such thing as crash testing at the time.
The general public reacted negatively to the lack of frame rails, and felt there was no protection in the event of a side impact. There was no way to say one way or another without crash testing, but consumers weren’t feeling it. This did not seem to affect sales, as Cadillac smashed sales records year after year, despite a legal battle that occurred during the X-frame’s production.
As people perished in X-frame vehicle crashes, GM was sued over its design in 1961 (Evans v. General Motors Corporation). The driver of a 1961 Chevrolet wagon died in an accident, and the plaintiff blamed the X-frame for being unsafe. The court did not find in favor of either party, and stated that a manufacturer had no legal obligation to make its wares “accident proof or fool-proof.”
The ruling was akin to a statement one might see on Facebook today, “Just don’t get into an accident, you’ll be fine.” GM called the ruling a win, as it could continue building X-frame cars. However, a new version of the C-body platform to replace the X-frame was already in the works by engineers at Oldsmobile and Pontiac. X-frame usage ended in 1964, apart from the Riviera which used it until 1970. In its place was a new perimeter-type frame that was quite different to the X-frame and ladder frame which preceded it.
Unlike the ladder frame that used crossmembers for rigidity, or the tubular X-frame that incorporated body panels into the chassis for stiffness, a perimeter frame was intentionally flexible in its design. It was meant to soak up impacts and NVH while in motion, and be paired to a very stiff body shell. The body shell would then be attached to the chassis with rubber mounts, which caused the bendable chassis and stiff body to work as a team.
The perimeter frame required no crossmembers at all, and meant the floor of the passenger compartment could be as low as possible. Side rails were back (it was important that consumers saw those in place) and joined together the front and rear parts of the frame. The side rails curved inward at the front and rear, to fit inside the wheel wells. Torsion boxes at all four corners joined the side rails with the front and rear frames, and were designed to flex and absorb impacts and reduce noise from the suspension.
The new perimeter frame design debuted on some GM cars in 1961, as Pontiac opted out of X-frames after 1960. The perimeter frame was lighter, cheaper to produce, allowed for more space in the passenger compartment, and better ride and handling. The design would prove to be the ultimate version of the passenger car frame, and remain in use through the end of the rear-drive traditional American sedan (Lincoln Town car and siblings, 2011).
Though it rode on a new, lighter frame design, the 1965 Fleetwood Eldorado expanded itself in its dimensions. Length increased from 223.5 inches in 1964 to 224” in 1965. Overall width increased from 79.5 inches to 79.9 inches.
Thanks to the new frame, overall height dropped a full inch, to 55.6”. The wheelbase remained the same as before, at 129.5 inches. The frame’s frame’s weight savings still showed despite the larger body size, as the Eldorado’s average weight dropped by about 100 pounds: between 4,700 and 4,900 pounds depending on specification.
Cadillacs were powered by the 340-horse 429 OHV V8 (7.0L), which continued into 1965 unchanged. It was again paired to the new and robust THM400 three-speed automatic (now standard across Cadillac). Both engine and transmission placement were modified in 1965, as the perimeter frame took up much less room underneath the vehicle. That meant the engine could be moved a full six inches forward in the frame, which made plenty of room to lower the transmission and increase interior space.
Cadillac was eager to tout its “True Center” drive line, which used a one-piece prop shaft and CV joints for additional quietness. The exhaust was also sonically balanced (by scientists), and had a completely new design. Cadillac stated it was the quietest exhaust ever. There was also an all-new suspension design, given the frame changes.
The company continued to market its “triple braking,” with independent front and rear braking systems, as well as the foot-operated parking brake as backup in emergency situations. The system was exclusive to Cadillac vehicles. More braking advancements came in the form of finned and self-adjusting brake drums, which promised better cooling and less servicing.
You can see the modern passenger car start to take shape around this time. Dials and controls looking modern, features once unimaginable becoming standard, and the industry beginning to nod at safety concerns (begrudgingly). The new frame design was a big leap forward underneath the large GM vehicles, though it wasn’t visible on the outside. That’s where we’ll pick up next time, as we review the exterior of the 1965 Fleetwood Eldorado.
[Images: GM]
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Source: The Truth About Cars
