| BMW 3/20[1] | |
|---|---|
 | |
| Overview | |
| Manufacturer | BMW |
| Also called | AM-1, AM-2, AM-3, AM-4 |
| Production | 1932–1934 |
| Assembly | Germany:Eisenach |
| Designer | Alfred Böning |
| Body and chassis | |
| Class | City car |
| Body style | four seatsaloon four seatcabriolet two seatconvertible coupé |
| Layout | FR layout |
| Powertrain | |
| Engine | 788 cc (48.1 cu in)OHVstraight-4 |
| Transmission | 4-speedmanual |
| Dimensions | |
| Wheelbase | 2,150 mm (84.6 in) |
| Length | 3,200 mm (126 in) |
| Width | 1,420 mm (56 in) |
| Height | 1,550 mm (61 in) |
| Kerb weight | 650 kg (1,433 lb) with saloon body |
| Chronology | |
| Predecessor | BMW 3/15 |
| Successor | BMW 309 |
TheBMW 3/20 PS was the first BMW automobile designed entirely by BMW. It was manufactured from 1932 to 1934, replacingthe 3/15 model that was initially anAustin 7 manufactured under licence from theAustin Motor Company.
The engine used in the 3/20 was based on the Austin Seven engine used in the 3/15, but its crankshaft ran in plain bearings instead of roller bearings and had an 80 mm (3.1 in) stroke, generating a displacement of 788 cc (48.1 cu in).[1] The new engine design also had a water pump and anoverhead valvecylinder head. These design changes caused the engine to generate 20 hp, but did not change the taxable horsepower rating of 3 PS, thus giving the model designation 3/20.[2]
The 3/20 was larger than the 3/15, with an 84.6 in (2,149 mm) wheelbase and a body 3 in (76 mm) lower than the 3/15.[2] The 3/20 used abackbone frame unrelated to the 3/15's Austin Seven "A" frame.[3][4] It inherited the 3/15 DA-4'sindependent front suspension and added aswing axleindependent rear suspension, using a transverse leaf spring similar to that used at the front.[1][4] The standard bodies for the car were built byDaimler-Benz inSindelfingen.[1][4]
Journalist and engineerJosef Ganz, who had criticized the 3/15 DA-4's suspension system in the magazineMotor-Kritik,[5] was contracted in July 1931 as a consultant in the design of the 3/20 AM-1.[citation needed]
Four versions of the 3/20 were built: AM 1, AM 2, AM 3 and AM 4, where AM denotedAutomobil München.[1]
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