Automobile Enthusiasts

that showed up in the 1963 (?) model year.

Head for Wikipedia....

Sorry, 1965. For 1964, a transverse leaf spring was added to reduce the jacking tendency:

First generation (1960–1964)

For 1964 significant engineering changes occurred, while the model lineup and styling remained relatively unchanged. The engine displacement was increased from 145 to 164 cu in (2.4 to 2.7 L) by an increase in stroke. The base engine power increased from 80 to 95 hp (60 to 71 kW; 81 to 96 PS), and the high performance engine increased from 95 to 110 hp (71 to 82 kW; 96 to 112 PS). The Spyder engine rating remained at 150 hp (112 kW; 152 PS) despite the displacement increase of the engine. 1964 saw an improvement in the car's swing axle rear suspension with the addition of a transverse leaf spring along with softer rear coil springs designed to diminish rear roll stiffness and foster more neutral handling. Spring rates could now be softer at both ends of the car compared to previous models. The heavy duty suspension was no longer optional, although all models now had a front anti-roll bar as standard. Brakes were improved with finned rear drums. The remaining pickup, the Rampside, was discontinued at the end of the model year.

Second generation (1965–1969)

The Corvair second generation arrived for model year 1965, noted for its lack of a "B" pillar and a new fully independent suspension replacing the original swing axle rear suspension. The Corvair used coil springs at each wheel.

Early Triumph Spitfires had a swing axle in the back, but the weight was biased toward the front, as that's where the engine was. I recall hearing about a fatal Spitfire rollover at NAS Patuxent River in the early 70s. A guy took the curve too fast, and the rear suspension jacked up.

Here's what that was all about:

Handling issues

The first-generation Corvair featured a rear engine + swing axle design similar to that of the Renault Dauphine and Volkswagen Beetle – a design which eliminates universal joints at the wheels and keeps the rear wheels perpendicular to the half-shafts. The design can allow rear tires to undergo large camber angle changes during fast cornering due to side g-forces causing "rebound" camber and decreasing the tread contact with the road surface, leading to a loss of rear wheel grip and oversteer—a dynamically unstable condition where a driver can lose control and spin. The problem is most severe with rear-engine swing axle combinations because of the greater inertial mass over the rear wheels and the higher center of gravity during rebound camber conditions. The additional high weight of a station wagon body also exacerbates the tendency. Oversteer is exacerbated by deceleration during cornering due to increased side g-force and lightened load on rear tires (lift-off oversteer). Understeer is common in front-engine cars, due to more weight, and inertia, on the front tires. Both conditions are dangerous when a car is driven at its cornering limits. Design options to ameliorate swing axle handling:



1960–63 swing axle suspension

....
For the 1965 model year, the Corvair received a fully independent rear suspension closely resembling that of the contemporary Corvette. The redesigned suspension reduced the rear roll center to half its previous height, using fully articulated half-axles that offered constant camber on the rear tires in all driving situations. This virtually eliminated the handling problems of the first-generation models.

Legal fallout

Consumer protection activist Ralph Nader addressed the handling issues of the first-generation (1960–1963) Corvair in his 1965 book: Unsafe at Any Speed. GM had over 100 lawsuits pending in connection with crashes involving the Corvair, which subsequently became the initial material for Nader's investigations. The book highlighted crashes related to the Corvair's suspension and identified the Chevrolet suspension engineer who had fought management's decision to remove—for cost reasons—the front anti-sway bar installed on later models. Nader said during subsequent Congressional hearings, the Corvair is "the leading candidate for the un-safest-car title". Subsequently, Corvair sales fell from 220,000 in 1965 to 109,880 in 1966. By 1968 production fell to 14,800. Public response to the book played a role in the National Traffic and Motor Vehicle Safety Act in 1966.

A 1972 safety commission report conducted by Texas A&M University concluded that the 1960–1963 Corvair possessed no greater potential for loss of control than its contemporary competitors in extreme situations.[24] The U.S. Department of Transportation (DOT) issued a press release in 1972 describing the findings of NHTSA testing from the previous year. NHTSA had conducted a series of comparative tests in 1971 studying the handling of the 1963 Corvair and four contemporary cars—a Ford Falcon, Plymouth Valiant, Volkswagen Beetle, and Renault Dauphine—along with a second-generation Corvair (with its completely redesigned, independent rear suspension). The 143-page report reviewed NHTSA's extreme-condition handling tests, national crash-involvement data for the cars in the test as well as General Motors' internal documentation regarding the Corvair's handling. NHTSA went on to contract an independent advisory panel of engineers to review the tests. This review panel concluded that "the 1960–63 Corvair compares favorably with contemporary vehicles used in the tests {...} the handling and stability performance of the 1960–63 Corvair does not result in an abnormal potential for loss of control or rollover, and it is at least as good as the performance of some contemporary vehicles both foreign and domestic." Former GM executive John DeLorean asserted in his book On a Clear Day You Can See General Motors that Nader's criticisms were valid.

Journalist David E. Davis, in a 2009 article in Automobile Magazine, noted that despite Nader's claim that swing-axle rear suspension were dangerous, Porsche, Mercedes-Benz, Tatra, and Volkswagen all used similar swing-axle concepts during that era. (The handling of other rear-engine swing-axle cars, particularly the Volkswagen Type I and II, has been criticized as well.) Some contend that Nader's lack of an automotive engineering degree or a driver's license at the time he wrote Unsafe at Any Speed disqualifies him as a critic of automotive safety. In response to Nader's book, Mechanix Illustrated reviewer Tom McCahill tried to get a 1963 Corvair to flip, at one point sliding sideways into a street curb, but could not turn over the vehicle.

The later ones seemed fine. I wouldn't mind owning one.

Full disclosure: I have never owned or driven one.