The 1960s were the final years of glory at General Motors. They had the lion’s share of the U.S. car sales, as well as a good portion of the European market via their Opel and Vauxhall brands. In the U.S, they built America’s only cars with four-wheel disc brakes, fuel injection, turbocharging and independent rear suspension. Before the decade was out, they would add another arrow to their quiver, the first American postwar car with front-wheel drive.
The idea had been floating around GM Engineering since 1954 when a front-wheel drive Unitized Power Package (UPP) was conceived for the 1955 La Salle II concept car. The Oldsmobile division became interested in the potential of the UPP and began developing and building prototype transaxles in 1960 coupled to a V6 engine. The following year the focus of development switched to a variety of large V8 engines and automatic transmissions; features expected by Oldsmobile’s high-end customers.
To make it all work, numerous technically intriguing creative solutions had to be developed and implemented.
By January of 1963, the basic layout was finalized with the engine fitted longitudinally over the front axle-line in approximately the normal position in large GM cars, with the automatic transmission’s torque converter attached to the rear. The remainder of the 3-speed Turbo-Hydramatic transmission was located in reverse-position alongside and parallel to the engine. Output of the torque converter was carried to the input shaft of the gearbox via a silent-type generated-link drive chain.
To insure optimum chain slack, four diameters of sprockets were used, hand-selected for each unit during assembly. The two-inch (50 mm) wide chain was 46.5” (118 cm) long, composed of 2,294 individual pieces. Residual chain noise of 1500 hz was ameliorated with a molded fiberglass-reinforced rubber cover over the chain housing.
Drive thrust from the transmission travelled by bevel gears to a unique, very narrow planetary differential and on to the axles. The right-hand axle passed under the center crankshaft main bearing and contained a rubber torsional damper. To enable the wide powertrain to sit alongside the steering gear, the entire UPP assembly was located 1.8” (46mm) to the right of centre.
To subject experimental drivetrains to the highest possible torque loadings, test cars by the end of 1963 were being fitted with Cadillac’s new 429 (7.0-litre) V8, GM’s largest passenger car engine. At that time, the biggest engine powering a production front-drive car was the 1.9-litre Citroën unit in the DS/ID.
GM engineers were working in uncharted territory. Not only would the Toronado have to feature the effortless big-engine torque and automatic transmission required by U.S. premium car buyers, it would also have to possess very low American luxury-car levels of Noise, Vibration and Harshness (NVH). These targets are difficult to achieve with front wheel drive as the engine and transmission mounts have to be firm enough to accommodate drive-axle torque reaction. Furthermore, any degree of steering wheel tug and torque steer would be unacceptable.
In addition to high levels of luxury, the Toronado was envisioned as a more sporting vehicle than the standard Oldsmobile lineup. To that end it was fitted with much higher spring rates than its large Oldsmobile brethren; 89% higher in front, and 57% higher at the rear. The steering ratio chosen was faster; 17.8:1 (nearly identical to the Oldsmobile 442) vs. 21.7 for the rest of the full-size Olds lineup. Unique among U.S. cars, a tie rod-mounted hydraulic steering damper was incorporated.
To free up room for the drive shafts, GM’s traditional coil springs were replaced up front with longitudinal torsion bars. The rear axle was a simple straight beam of hat-section profile supporting the car via a set of friction-free single-leaf rear springs. In addition to the traditional vertical dampers, the rear axle featured a second pair mounted longitudinally in a horizontal plane. GM and Firestone jointly developed a unique special tyre for the Toronado, the T-FD.
To insure the smoothness and silence desired a front subframe was envisioned from the start, but during development it grew rearward in length long enough to support the leading eyes of the rear leaf springs.
The slightly raised UPP combined with the stylishly low Toronado front end required the engine height to be reduced by 2.6” (65 mm), accomplished by designing an extremely flat air cleaner housing and intake manifold. This task was simplified to a degree in that the engine no longer had to be tilted back to match a longitudinal drive driveshaft angle.
The Toronado debuted to largely positive reviews and garnered acclaim for handling, smoothness and refinement. Autocar judged its general road behavior “clearly superior to any equivalent rear-wheel drive product” and reported that “no pull or other influence comes back through the powered steering to the driver’s hands, even on full lock” and further stated that the Toronado “In one blow destroys any illusions about front-drive being unsuitable for very large and powerful vehicles.”
The completely flat floor enabled by the UPP front-drive architecture bestowed front and rear centre occupants with the same generous legroom and deep seat cushioning as outboard passengers, allowing the Toronado six-passenger coupé to transport a half-dozen adults with a degree of space and comfort unknown in competitive vehicles with conventional drivetrains.
Ingress and egress were aided by extra-wide doors, 3.5” (90 mm) longer than existing full-size Oldsmobile coupés. Deluxe models featured dual interior door handles, the second set accessible to rear-seat passengers.
The Toronado launched at the pinnacle of GMs engineering prowess. Just a year prior, the Corvette had received America’s first four-wheel disc brakes and the second generation Corvair was introduced to rave reviews. The Toronado completed the trifecta. It’s innovative and powerful UPP proved smooth, well-mannered and trouble-free; the automatic transaxle soon serving behind Cadillac’s massive 500 cubic inch (8.2-litre) V8 in the Eldorado, easily coping with its prodigious 550 ft/lbs (746 N-m) of torque.
Later the complete Toronado UPP was drafted by GM Truck & Coach to propel the 11,700 lb (5,307 kg) GVW GMC Motorhome.
Wrapping the innovative drivetrain was one of GMs most attractive 1960s body designs. Dispensing with the pivoting front vent windows which had been a feature of GM-Fisher bodies since 1933, the Toronado (and its E-body sister the Buick Riviera) introduced GM’s first windows-up passive flow-through ventilation system with cabin air-extraction outlets located beneath the rear window.