Engineering:Saab Sonett

Saab Sonett
Sonett I (type 94)
Overview
Manufacturer	Saab Automobile
Body and chassis
Body style	Roadster Coupé

The Saab Sonett is an automobile manufactured between 1955 and 1957 and again between 1966 and 1974 by Saab of Sweden. Sonetts share engines and other components with Saab 93, 95 and 96 of the same era. It was mainly intended for the lucrative American export market and was only offered intermittently in the Swedish domestic market (model years 1968 and 1972).

The first prototype, now known as the Sonett I, is a two-seat, open-top, lightweight roadster racer which, ten years later, evolved into the commercially distributed Sonett models II, V4, and III.

Sonett I

Sonett I
Overview
Also called	Saab 94, super sport prototypes
Production	1955–1957
Designer	Sixten Sason
Body and chassis
Body style	2-door and 2-seat roadster, RHD
Layout	MF layout
Powertrain
Engine	748 cc three-cylinder Saab two-stroke
Dimensions
|uk|Kerb|Curb}} weight	600 kg (1,323 lb)
Chronology
Successor	Saab Sonett II

In the 1950s, Rolf Mellde—a Saab engine developer and race enthusiast—along with Lars Olov Olsson, Olle Lindkvist, and Gotta Svensson, designed a two-seat roadster prototype in a barn in Åsaka, near Trollhättan (the site of the main Saab manufacturing facility). The limited research-and-development project, with a total budget of only 75,000 Swedish kronor, became known as the Sonett, a name derived from the Swedish phrase Så nätt den är ("how neat it is", or more literally "it's so neat") supposedly said by Mellde when faced with the prototype.

The Saab Sonett, also called the Super Sport or Saab 94, was introduced on 16 March 1956 at Stockholm's Bilsalong (motor show). Featuring a three-cylinder 748 cc two-stroke engine generating 57.5 horsepower (42.9 kW) and a 70 kilograms (150 lb) aluminium box-style chassis from Swedish designer Sixten Sason, the Sonett I was an advanced low-weight 600 kg (1,323 lb) racer based on aircraft design concepts.

Saab Sonett I, rear view

With a projected top speed of 120 mph (190 km/h), the Sonett I had the prospect of success on the European race circuit, and a production run of 2,000 units was planned for 1957. However, race competition rules changed, permitting modified production cars into race classes that Saab had envisioned for its purpose-built Sonett, and the economic and marketing viability of the project faded.

Only six Sonett I vehicles were made between 1955 and early 1957, all RHD. The original prototype, known as "No. 1" and built with a manually-crafted glass-reinforced plastic (GRP, or "fiberglass") body, served as the reference model for the other five cars. An extremely rare vehicle, only two Sonetts I exist in the United States. Chassis number 2 was in the GM Heritage Center Collection but it was sold to Saab Cars North America (SCNA) after GM's 2009 bankruptcy. After Saab, too, went bankrupt in 2012, it was sold on to the Saab Heritage Car Museum USA in South Dakota.

In September 1996, rally driver Erik Carlsson broke the Swedish record for the under–750-cc engine class with a speed of 159.4 km/h (99.0 mph) in the restored Sonett I original prototype "No. 1".

Sonett II

Sonett II and V4
Sonett II (1966)
Overview
Also called	Saab 97
Production	1966-1969
Designer	Björn Karlström
Body and chassis
Body style	coupé, LHD
Layout	FF layout
Powertrain
Engine	841 cc Saab two-stroke I3 1,498 cc Ford Taunus V4 engine
Chronology
Predecessor	Saab Sonett I
Successor	Saab Sonett III

In the early 1960s, Björn Karlström, an aircraft and automotive illustrator, and Walter Kern, an engineer at Massachusetts Institute of Technology, independently suggested a two-seat roadster with Saab components and a two-stroke engine called the "Shrike". Two prototypes were developed: the Saab MFI13 by Malmö Flygindustri, and the Saab Catherina by Sixten Sason.

After some modifications, the MFI13 was put into limited production (28 units) in 1966 as the Sonett II, manufactured at the Aktiebolaget Svenska Järnvägsverkstäderna (ASJ) in Arlöv. Inside Saab, it was designated model 97. A further 230 units were assembled in 1967, but as the two-stroke engine became increasingly uncompetitive in the US market, a switch to the Ford Taunus V4 engine was made in the middle of the 1967 production year, and the model was renamed the Sonett V4. Apart from the engine and related drivetrain, the Sonett II and Sonett V4 share much of their componentry. The additional weight did require some strengthening of the chassis and suspension pieces, and the wheels were half an inch wider than the four-inch units used on the Sonett II. Approximately 50 percent of the Sonett II production has survived, preserved or maintained by museums, collectors, and race enthusiasts. The 1967 year holds the distinction of becoming the last 2 stroke engine passenger automobile sold new in the United States.

Like the Sonett I prototype, the Sonett II fiberglass body was bolted to a box-type chassis with an added roll-bar to support the hard top. The entire front hood section hinged forward to allow easy access to the engine, transmission, and front suspension. Equipped with a three-cylinder, two-stroke engine generating 60 PS (44 kW; 59 hp), the Sonett II achieved 0 to 100 km/h (0–62 mph) time of 12.5 seconds, with a top speed of 150 km/h (93 mph). All Sonett IIs were left hand drive (LHD).

The rear of a 1966 two-stroke Sonett II

Designed as a race car, the Sonett II competed successfully against other small European sports cars, including the Austin-Healey Sprite and Triumph Spitfire, in Sports Car Club of America (SCCA) races of the period. Due to low production volume, Sonett IIs were disqualified from certain competitions. By 1967, the two-stroke engine failed to meet US emission control standards. In 2011 a two-stroke Sonett II achieved 109 miles per hour (175 km/h) at the Bonneville Salt Flats. Of the 28 Sonett IIs manufactured in 1966 all were equipped with 841 cc three cylinder two-stroke engines. SAAB produced serial numbers 29 through 258 with the two-stroke engine, serial number 259 was the first Sonett to have the V4 engine.

All Sonett II transmissions had a freewheel that could be engaged and disengaged while in motion via a pull handle down near the throttle pedal. The freewheel was required in the normal (non-oil pump engines) SAAB two stroke engines but not in the racing engines that had an oil injection system fed from a supply tank, nor in the Sonett V4 since it had a four-stroke engine with the common recirculating pressure lubrication.

The Škoda-engined ÚVMV 1100 GT was based on the Sonett II.

Sonett V4

1968 SAAB Sonett V4

When Saab started using the Ford Taunus V4 engine in their 95, 96, and Monte Carlo models, an upgrade for the low-volume Sonett II became economically feasible. The Sonett V4 was introduced with a 1,500 cc Ford V4 engine in the middle of the 1967 model year starting with serial number 259. A new "bulge" hood, designed by Gunnar A. Sjögren, was required to clear the larger V4 engine, with a slight right offset to avoid obstructing the driver's view. This asymmetrical hood shape, criticized by both the automotive press and within Saab itself, contributed to the motivation for the 1970 Sonett III redesign.

The Ford V4 engine produced 65 hp (48 kW), and—combined with the car's lightweight chassis and fiberglass construction—allowed the V4 model to accelerate from 0 to 100 km/h (0 to 62 mph) in 12.5 seconds, with a top speed of 160 km/h (99 mph). The V4's dashboard was wrinkle finished black, unlike the wooden panel used in the Sonett II.

Following the low-volume 1966–67 Sonett IIs, Saab ramped up Sonett V4 production to meet minimum SCCA requirements, assembling 70 units in the 1967 transition year, 900 units in 1968, and 640 units in the final 1969 production year—a total of 1,610 Sonett V4 vehicles. The 1969 models can be recognized by their taller seat backs and by having a lid for the glove compartment, while the heater was also made somewhat more efficient.

While the Sonett V4 was assembled in Sweden, nearly the entire production was exported to the United States, with an MSRP of between US$3,200 and US$3,800 (US$22,310 to US$26,493 in today's dollars). In addition to its unusual fiberglass body, the Sonett V4 featured advanced safety features for its day, including a roll bar, three-point seat belts, and high-back bucket seats to protect against whiplash injury. Sonett V4s also sported a few oddities compared to standard American sports cars like e.g. Corvette, such as front wheel drive; a freewheeling clutch that disengaged automatically whenever the accelerator pedal was no longer pressed, and a column-mounted shifter, rather than a typical floor-mounted shifter.

In spite of lackluster Saab marketing, unusual features, and quirky design, the Sonett V4 found a niche market in the US, propelled by successful SCCA racing performances of the Sonett II. Its primary competitors were British roadsters, including the MG Midget and MG MGB, the Triumph TR5, the TVR Grantura and the Austin-Healey Sprite Mark IV.

The Clean Air Act of 1970 prompted engineering modifications to the Ford V4 emission control system that were difficult to reconcile with the Sonett II/V4 body style which then led to the Sonett III redesign.

Sonett III

Saab Sonett III
Overview
Also called	Saab 97
Production	1970–1974
Designer	Sergio Coggiola, Gunnar A. Sjögren
Body and chassis
Body style	coupé, LHD
Layout	FF layout
Related	Saab Sonett II
Powertrain
Engine	Ford Taunus V4 engine
Dimensions
Wheelbase	2,150 mm (84.6 in)
Length	3,900 mm (153.5 in)
Width	1,500 mm (59.1 in)
|uk|Kerb|Curb}} weight	880 kg (1,940 lb)
Chronology
Predecessor	Saab Sonett V4 (Sonett II body with Ford V4 engine)

The 1970 redesign of the Sonett V4, named the Sonett III, was initially undertaken by Sergio Coggiola, but Gunnar A. Sjögren altered it to fit the existing Sonett II chassis without expensive manufacturing-line changes. Hinged rear-window glass replaced the Sonett II/V4 rear compartment hatch door. With the mandate for a "bulge-less" hood, the engine compartment opening evolved into a small front popup panel, resulting in more limited access than in the Sonett V4. Extensive engine work required the removal of the entire front hood section.

1972 Saab Sonett III dashboard

To help adapt the car to US market tastes, the Sonett III featured a floor-mounted shifter (instead of the Sonett V4 column-mounted shifter) and optional dealer-installed air conditioning. The Sonett III's hidden headlamps were operated manually using a lever. US safety regulations required new low speed impact proof bumpers after 1972, significantly detracting from its Italian-inspired design. All Sonett III were LHD.

While the 1970 and 1971 model years initially had the same 1500 cc Ford Taunus V4 engine as the Sonett V4, emission control requirements reduced the available horsepower. The model years 1972 to 1974 of the Sonett III used the 1700 cc Ford V4, but to meet increasingly strict federal regulations, net power output remained the same as the 1500 cc engine, at 65 horsepower (48 kW). Still, the Sonett III accelerated from 0–100 km/h (0–62 mph) in 13 seconds, and—due to a higher differential gear ratio (42 teeth on the ring gear and 9 teeth on the pinion gear) than the standard 95/96 transmission (39:8)—achieved a top speed of 165 km/h (103 mph), aided by a drag coefficient of 0.31 cd.

Rear view of a 1972 Saab Sonett III in green

Disappointing sales, especially during the 1973 oil crisis, led Saab to end production late in 1974. A total of 8,368 Sonett IIIs were manufactured between 1970 and 1974.

By then the production total for models Sonett II, Sonett V4 and Sonett III had reached 10,236 units.

During that time Saab USA's president Jonas Kjellberg was interested in creating a new generation of Sonett in collaboration with Reliant and styled by Tom Karen of Ogle Design, in a deal where the latter would design, engineer and assemble the car for the US market. However the project was brought to an end when the board at Saab rejected the proposals, when Kjellberg presented Reliant's business plan for the new Sonett.

SAAB also used the Sonett III for test builds powered by a Rankine cycle steam engine. One of the test cars survived and was at auction in Stockholm in July 2019.

Cancelled new Sonett

The Sonett name was planned to be revived as the production version of the Saab PhoeniX concept. Designed by Jason Castriota as an affordable halo car for Saab, it would have been a 2+2 sports car producing up to 400 hp in its highest form, and used the new Phoenix platform that would have underpinned the next generation 9-3 and 9-1 compact. These projects were cancelled with the dissolution of Saab in 2012.

External links

• Saab Sonett Super Sport