Duesenberg Model A

Fred and August Duesenberg built aircraft and marine engines during World War I, and used this expertise to design and build racing engines and to design a car. The Duesenberg Automobiles and Motors Company was incorporated in Delaware and founded to manufacture and market the production car while Duesenberg Brothers, a separate organization, built racing cars and engines.

The Duesenberg Straight Eight was introduced in late 1920 at the Commodore Hotel in New York City, but production did not begin until late 1921. The main reason for the delay was Fred Duesenberg's decision to redesign several aspects of the car, including the valvetrain. The headquarters and manufacturing facilities of the Duesenberg Automobiles and Motors Company were relocated from Newark, New Jersey, to Indianapolis, Indiana during this time. The move was completed in May 1921, but the redesign was not.

Drivetrain

The Straight Eight was the first car in series production in the United States with a straight-eight engine. The engine had a cast iron block, a detachable cast iron cylinder head with hemispheric combustion chambers, and an aluminum lower crankcase and oil pan. The crankshaft ran in three main bearings. While the prototype Straight Eight shown at the model's introduction had horizontal valves of the type used in earlier Duesenberg-designed marine and racing engines, the model that entered production had a shaft-driven single overhead camshaft which used rockers to operate two valves per cylinder.

The engine used a single updraft carburetor; early versions used a Stromberg unit, which was replaced by a Schebler unit. The carburetor was on the right side of the engine, the mixture went into a passage through the engine block to the intake manifold on the left side of the engine. Ignition was by Delco coil and breaker points, with the distributor at the end of the generator/starter unit.

With a 2.875 in (73.0 mm) bore and a 5 in (127.0 mm) stroke, the engine had a displacement of 260 cu in (4.3 L). The standard compression ratio of five to one yielded 88 hp (66 kW) at 3600 rpm and 170 lb⋅ft (230 N⋅m) of torque at 1500 rpm. This gave the Model A a top speed of 71 miles per hour (114 km/h).

The transmission was an unsynchronized three-speed gearbox with a single dry-plate clutch. The drive shaft was enclosed in a torque tube and drove the live rear axle through a spiral bevel drive.

Chassis

The chassis was based on a pressed steel ladder frame with channel-section side members and fabricated and tubular cross members. Suspension was by semi-elliptic leaf springs and Watson Stabilator dampers front and rear, with a tubular beam axle at the front and a live axle and radius rods at the rear. The standard wheelbase was 134 inches (3,400 mm), stretched to 141 inches (3,600 mm) for seven-passenger bodies. The front and rear tracks were both 56 inches (1,400 mm) wide. Center-locking wire wheels with 5" x 33" tires were used front and rear.

The Duesenberg Straight Eight was the first production automobile to use Lockheed Corporation hydraulic brakes on all four wheels. The brakes on the front wheels were 16 inches (410 mm) in diameter and were finned to dissipate heat. The fluid used in the system was a mixture of glycerine and water.

The initial production target was 100 cars per month. By the end of 1922, after slightly more than a year of production, fewer than 150 Duesenberg Straight Eights had been built. Manufacture continued through several changes in management, placement of the Duesenberg Automobiles and Motors Company into receivership in January 1924, and the restructuring of the company into the Duesenberg Motor Company in February 1925. Production was ended following the October 1926 purchase of the company by E. L. Cord, with some 650 Straight Eights having been built.

The Model A was succeeded in 1927 by the Model X, a larger derivative with an exceedingly small production run of approximately twelve units.

It rode on a 135 in (3,400 mm) wheelbase, and had an engine of the same bore and stroke but with a non-crossflow head that delivered 100 horsepower (75 kW).

Despite its regional and worldwide automotive firsts, the Straight Eight has been obscured by the later Model J. It is no longer widely known by the Straight Eight name under which it was marketed and sold, having been renamed the "Model A" after the introduction of the Model J.