BMW Isetta

BMW
BMW Isetta, built in 1955
Isetta
Production period:	1955-1962
Class :	Light vehicle
Body versions :	Coupe
Engines:	Gasoline engines : 0.25-0.30 liters (8.8-9.6 kW)
Length:	2285 mm
Width:	1380 mm
Height:	1340 mm
Wheelbase :	1500 mm
Empty weight :	350-370 kg

The BMW Isetta was a scooter that Bayerische Motorenwerke built from 1955 to 1962. The manufacturer called the vehicle, to be classified between a motorcycle and a car, a "motocoupé".

background

Rear view of a BMW Isetta 250 from 1957

Year of construction 1956

"Export" model from 1957

"Export" model 1957 with ventilation flaps

Police Isetta, from 1957 a service vehicle in Cologne and later until 1968 an escort vehicle for heavy loads in Bergisch Gladbach

View of the interior of an Isetta

Cockpit of an Isetta from 1955 with additional instruments and a radio built in afterwards

Isetta logo from 1959

BMW Isetta of the German Federal Post Office

Rear view of a three-wheeler Isetta

BMW Isetta in daily use (photographed in February 1972)

"Big Isetta" BMW 600

Isetta engine and transmission (the coil spring visible in the picture is not a standard component.)

During the Second World War, BMW mainly built motorcycles and aircraft engines in the two Munich plants in Milbertshofen and Allach . After the end of the war in 1945, BMW was unable to resume car production because the BMW Eisenach automobile plant , located in the Soviet occupation zone , was expropriated and became part of the Soviet joint-stock company Awtowelo .

Vehicle production at BMW began in 1948 with motorcycles . The first car newly developed by BMW after the war and manufactured from 1952, the BMW 501 , known as the “Baroque Angel” , was an economic failure, because the car with a six-cylinder engine was only affordable for a small group of buyers. Given the small number of units, the sales price of DM 15,000 (1952) did not cover the production costs. Adjusted for inflation, the selling price for 2020 is around 38,360 euros.

For many customers, motorized two-wheelers were initially considered at best, and full-fledged cars, such as the Volkswagen , were often unthinkable - also because they lacked a class III driver's license. The old IV driving license was also valid for vehicles up to 250 cm³ displacement. Some manufacturers used this regulation with scooter mobiles (for example the Goggomobil or the Messerschmitt cabin scooter ). Back then, however, BMW only offered motorcycles and the luxury class vehicles BMW 502 or 503 with V8 engines.

Importance of the Isetta for BMW

In Italy, Renzo Rivolta, the owner of the refrigeration system and motorcycle manufacturer Iso Rivolta , had aircraft engineers Ermenegildo Preti and Pierluigi Raggi design a scooter in an unusual form: the Iso Isetta , which was presented in 1954. Like a cargo glider, you opened a large front door on this vehicle; Preti had designed an aircraft of this type (Aeronautica Lombarda AL.12) during the Second World War. The steering wheel swiveled with the front door forwards and to the side and thus offered a good entry into the interior space, which was sufficient for two people.

BMW gradually got into a crisis in the early 1950s. There was no time to plan and design a miniature car, there was only one other option: building under license . At the Turin Motor Show , the BMW delegation became aware of the Isetta and saw it as an opportunity. After signing the license agreement with Iso, an Isetta was brought into the factory and the design was improved. The Isetta got a single-cylinder engine from the BMW motorcycle range, converted to fan cooling and a starter alternator. Like the original, the BMW Isetta has two rear wheels; for Austria there was a three-wheel version because it was considered a motorcycle. The constructive changes proved to be a success.

The Isetta was unable to avert the financial crisis at BMW, but at least it saved time. On March 5, 1955, it was presented to the public at a price of DM 2,580. The trade press was impressed. Between 1955 and 1962, 161,728 were Motocoupé sold. Only the Goggomobil exceeded this number . The success of the Isetta gave BMW the much-needed funds and time to develop new models. This is how the BMW 600 , the successful BMW 700 and the New Class came into being , which for a long time became the basis of BMW's success. The Isetta is one of the symbols for the rapid reconstruction of Germany after 1945, the so-called economic miracle .

history

The first version of the Isetta was built from April 1955 to March 1956. Both the 250 and 300 models (presented in December 1955) had a large panoramic rear window made of Plexiglas that was drawn around the corners , fixed side windows and triangular windows that could be opened. The all-round visibility was very good. In October 1956 the second version, the "Export" 250 and 300, came onto the market. They differed from the previous model in particular in that they had sliding windows on the sides and a smaller safety glass rear window. The vent windows were omitted and both models also received telescopic shock absorbers on the front axle. The 300 standard model still had friction dampers.

BMW had obtained the right to export to Scandinavia, Austria and Switzerland from Iso, while the Benelux countries, Spain and France were given by the Spanish licensee Iso España (identical to Iso Italy) and the French licensee Vélam (who owned the Vélam- Isetta developed as a self-supporting structure) were supplied. In Belgium, Moorkens (now Alcopa) produced. In addition, the BMW Isetta was built under license in Brighton as the Isetta of Great Britain , where right-hand drive and tricycle versions were also regularly offered. Brighton also supplied the Scandinavian market as well as Australia and New Zealand. In Brazil, the Romi-Isetta was built by Indústrias Romi from 1956, initially under license from Iso Italy, and from 1959 in the BMW form under license from BMW.

The Isetta was also a success on the export markets. For example, there was a US model with larger sealed beam headlights and larger taillights, as well as a tropical model with adjustable air intake through the front door. The Isetta was also offered in a convertible version, in which a folding top could be folded down instead of the Plexiglas pane of the standard version; the convertible version of the export Isetta then had a shortened and modified sheet metal roof construction in the rear part for the rear folding top, which remained the same size. A pick-up model derived from the Cabrio-Isetta, in which a load structure was used instead of the rear hood, found few buyers.

In 1957 the four-seater BMW 600, inspired by the Isetta, came onto the market, which in addition to the front door has a side door on the right and a rear bench seat. The spare wheel is also housed in the front door. The BMW 600 has a two-cylinder boxer engine with 585 cm³ and 19.5 hp in the rear. Front and rear wheels are suspended from longitudinal swing arms. The engine of the 600 series BMW was also a redesigned motorcycle engine, this time from the BMW R 50 model with an enlarged bore.

During the entire construction period, the Isetta focused mainly on eliminating weak points and improving production. The essential elements always remained the same.

Production of the BMW Isetta was stopped in May 1962. Until the early 1970s, it was still quite common in the streets.

technology

Frame of the BMW Isetta

The air-cooled single-cylinder four-stroke engine initially had a displacement of 245 cm³ and developed 12 HP (8.8 kW), from February 1956 there were also 295 cm³ and 13 HP (9.6 kW). It is installed across the right side of the car behind the bench seat. A single-disk dry clutch and the gearbox are flanged to the left of the engine. The Isetta has a reverse gear, which was not a matter of course in a small car, and four non- synchronized forward gears, which require intermediate clutches and double-declutching to shift down, and small shift pauses and intermediate clutches are also beneficial when shifting up. The gearshift lever is to the left of the driver, from where the gearshift commands are sent to the transmission via a linkage and a cable. The shift pattern with first gear on the right rear and fourth gear in the front left takes getting used to.

The rear wheels are driven by a transverse cardan shaft with rubber joints and a duplex chain running in an oil bath. Due to the small track width of the rear axle of only 52 cm, no differential is required.

The Isetta has a tubular steel frame on which a two-seater all-steel body with front entry is placed. The side windows and the panoramic window in the rear of the 1955 and 1956 models were made of Plexiglas . Initially, apart from the sliding roof, there was only a triangular vent window on the left and right for ventilation. In addition to the sliding windows at the side, the "Export" model from 1957 has two ventilation flaps in the door, which the sales brochure said that they guarantee "draft-free ventilation" and "give the face another interesting feature". The first version was initially built on as the "Standard" model. The body and chassis of the Isetta and the BMW 600 can be separated from each other.

The 1955 BMW Isetta can be recognized by its long headlight housings and a triangular brake light lens; from 1956 the headlight housings were egg-shaped.

The front wheels are individually suspended according to the system invented by André Dubonnet : short, pushed arms that are pivoted together with their bearings for steering. The Isetta has spindle steering, the steering nut of which acts on the steering lever of the left front suspension via a lever and a steering rod.

Initially, the swingarms of the standard version had friction shock absorbers and acted on horizontal coil springs via a toggle lever and tie rods; in the export model published in 1957, the springs stand together with telescopic shock absorbers directly next to the kingpin in a sheet metal housing screwed to the swing arm bearing. The top of the damper is connected to the housing via a rubber mount and sits on a pin on the swing arm. The brake anchor plate can be rotated on the swing arm and is connected to the swing arm support via a link under the swing arm in order to reduce the amount of boom when braking. BMW retained this design with the vertical springs for the successor BMW 600 and 700.

At the rear, the four-wheeled Isetta has a rigid axle on two quarter-elliptical springs with two telescopic shock absorbers. As a drawbar axle, it is supported by its chain case and a short handlebar on the frame.

Tricycleisettas have a U-shaped swing arm made of tubular steel at the rear, which is connected to the frame via a joint formed from two rubber bearings and is supported on the quarter-elliptical springs. The chain case is attached to the left leg of the U. The bike is cantilevered (only from one side) on the chain case.

The foot brake acts hydraulically on all wheels, with only one brake drum being installed for the rear wheels. The diameter of the brake drums is 180 mm, the total braking area 324 cm².

inner space

The spare wheel is located between the continuous bench seat and the engine. The handbrake (from 1956) and operating lever for the choke and later also for the heating are located like the gearshift lever on the left outer wall. A small dashboard is attached to the left-hinged front door, to which the steering column that swivels is also attached. A heater was not offered as standard in the first two years of construction. The interior panels are made of printed cardboard, the few cutouts are embellished with piping .

Like the Iso-Isetta, the first version of the BMW model also had a folding top as standard. In the second version and in the BMW 600, a folding top was not part of the standard equipment, but could be ordered as an optional extra, manufactured by Golde.

Fuel consumption

The Isetta's tank is installed in the rear above the rear axle; it holds 13 liters of petrol including a 3 liter reserve and has a fuel tap. In theory, that's enough for up to four hundred kilometers of driving. With the appropriate driving style or worn piston rings, consumption increases to significantly more than 5 liters per 100 km.

With a gasoline consumption of "around 3.45 liters / 100 km at 57 km / h" (factory specification), the BMW Isetta 1955 can be regarded as the first 3-liter car in the world to be built in large series. Their small single cylinder engine and light weight made them so economical. At the same time, with 161,728 units, it is probably the best-selling single-cylinder car in the world.

BMW Isetta tricycle special

A three-wheeler version of the BMW Isetta was produced in 1959/60 in over 1500 pieces for export based on the "BMW Isetta 300 Export"; in this way, favorable taxation was used in the countries concerned because it was classified as a motorcycle. The rear wheel was guided on a swing arm and driven by a completely encapsulated chain on the left side of the vehicle.

Technical specifications

Parameters	BMW Isetta 250	BMW Isetta 300
engine	Single-cylinder four-stroke engine (right behind the seat bench, across) with fan cooling
Displacement	245 cc	298 cc
Bore × stroke	68 × 68 mm	72 × 73 mm
power	12 HP (9 kW) at 5800 rpm	13 hp (9.5 kW) at 5200
maximum torque	1.45 mkp (14 Nm) at 4500 rpm	1.9 mkp (18.5 Nm) at 4600 rpm
compression	6.8: 1	7.0: 1
Valve control	Camshaft underneath, bumpers and rocker arms, valves hanging in a V-shape
coupling	Single-disc dry clutch
transmission	Four-speed gearbox (not synchronized) + reverse gear; Shift lever on the left
Rear axle drive	transverse cardan shaft and duplex chain (adjustable)
construction	All-steel body on tubular frame
Front suspension	pushed trailing arm (short swing)
Rear suspension	Rigid axle
suspension	Front coil springs, quarter-elliptic leaf springs at the rear, telescopic shock absorbers
Track width front / rear:	1200/520 mm
wheelbase	1500 mm
wheel size	4.80-10 ″
Brakes	Drum brake; Hydraulically operated foot brake acting on four wheels, handbrake with cable pull on the rear wheels (only one brake drum)
steering	Spindle steering, 2.5 turns from lock to lock
Dimensions L × W × H	2285 mm or 2355 mm × 1380 mm × 1340 mm
Turning circle	approx. 8.30 m
Empty weight (without driver)	approx. 370 kg
maximum weight allowed	600 kg
Top speed	85 km / h
Standard consumption	3.7 l / 100 km	3.9 l / 100 km
Price September 1961	2650, - DM + 45, - for heating	2710, - DM + 45, - for heating

Data according to sales brochures and Motor Klassik .

The Isetta today

Microlino at the Geneva Motor Show 2018

Today the Isetta is an interesting piece of automotive history.

The English company Tri-Tech, originally a supplier of spare parts, sold an Isetta replica under the name "Tri-Tech Zetta 300".

Duesen Bayern manufactures another replica of the Isetta 250 in Japan. This version is based on the Nissan Hypermini platform . The vehicle parts used for the replica come from BMW , Nissan and Toyota .

Micro Mobility Systems announced the market launch of an Isetta modeled electric vehicle Microlino for 2018. The scooter was presented at the Geneva Motor Show 2016.

Original BMW Isettas can be seen at classic car events such as the annual meeting of the Isetta Club and in museums, for example in the BMW Museum in Munich, in Bonn in the House of History , in the Karlsruhe Transport Museum or as a police version in the 1st German Police Oldtimer Marburg Museum .

Others

Nicknames

In popular parlance, the Isetta was also known as the “Knutschkugel” or “pothole detector” (because of the significantly narrower track width at the rear). Other nicknames - because of the unusual door construction - were "Hallelujah Auto" and "Advent Auto" - alluding to the Advent song " Power up the door" . Occasionally, the expressions "asphalt bubble" and " nipple spider " were also used - although they were used for many small cars .

taxation

In 1955, Der Spiegel reported on unfair taxation cases of the Isetta by German tax authorities. Some tax offices correctly demanded the motor vehicle tax rate for a car at DM 44 per year, but wanted to credit only 22 pfennigs per kilometer for the distance flat rate as for a motorcycle. For passenger cars that would have been 50 pfennigs per kilometer.

Long distance travel

The motor journalist Fritz B. Busch described a trip to Italy with his wife and nine-year-old daughter in a BMW Isetta, built in 1959, with the 300 engine. The three of them had exactly 115 cm available on the bench. The camping equipment was lashed to the rear luggage rack, smaller luggage was in the footwell. The first stage from Hamburg to Munich, which was not affected by any traffic jams, took around 16 hours, from where it continued over the Brenner Pass to Venice. The trip to Venice, excursions in Italy and also the return trip to Hamburg survived the overloaded Isetta without any breakdowns, only the exhaust had vibrated a little loose, reported Busch and finally remarked that long-distance trips with 13 HP were much more amusing at that time than today; it should be repeated occasionally.

Broadcast reports

• From Knutschkugeln and Goggomobiles - Documentation , NZZ Format 2005 (YouTube from July 29, 2016)

Web links

Commons : BMW Isetta  - collection of images, videos and audio files

• BMW Isetta series. In: BMW history. BMW AG, accessed on May 15, 2016 (dossier in the BMW Group Archive). 

Remarks

1. ↑ The "standard consumption" according to DIN 70030 was determined with a constant three-quarters of the maximum speed, but no more than 110 km / h, on a level route, so that the values ​​were always higher in practice.

Individual evidence

1. ↑ RGBl. I 1937, p. 1215: Driving license IV also for light motorcycles ; Entry into force: January 1, 1938.
2. ↑ https://www.flightglobal.com/pdfarchive/view/1948/1948%20-%201888.html
3. ↑ Annika Biss: The internationalization of Bayerische Motoren Werke AG: From pure export business to the establishment of our own subsidiaries abroad 1945–1981 . Walter de Gruyter, Berlin 2017 ( limited preview in the Google book search).
4. ↑ BMW Isetta Cabriolet. In: BMW history. BMW AG, accessed on October 31, 2016 (dossier in the BMW Group Archive).  
5. ↑ BMW Isetta Pickup. In: BMW history. BMW AG, accessed on October 31, 2016 (dossier in the BMW Group Archive).  
6. ↑ ^{a b c d} BMW Isetta and its competitors , Schrader Verlag, Stuttgart 1996, ISBN 3-613-87010-X .
7. ↑ http://www.isetta-online.de/vorderachse_explosion.htm
8. ↑ Definition of large-scale production (diagram on page 5) (PDF; 106 kB).
9. ^ Horst Seehofer: Opening of the Bavarian State Exhibition 2010 "Bavaria - Italy". (No longer available online.) Bavarian State Government, May 20, 2010, archived from the original on December 24, 2011 ; accessed on November 28, 2017 (speech by the then Prime Minister Horst Seehofer): "By the way, it was the 3-liter car that is much touted again today [...]"  
10. ^ Werner Oswald: All BMW automobiles since 1928. Motor Buch Verlag, p. 112 and p. 144.
11. ^ Andy Schwietzer, Manfred Seehusen: Isetta: A car moves the world .
12. ↑ BMW Isetta Tricycle Special. In: BMW history. BMW AG, accessed on October 31, 2016 (dossier in the BMW Group Archive).  
13. ↑ ^{a b c} supplement to Motor Revue , Vereinigte Motorverlage, Stuttgart, issue 39, autumn 1961 edition.
14. ↑ Information in the sales prospectuses 1956 and 1959.
15. ↑ Schrader-Motor-Chronik: BMW Isetta and its competitors . Schrader-Verlag, Stuttgart 1996, ISBN 3-613-87010-X .
16. ↑ Gerald Nelsen, Dirk-Michael Conradt: Brief History . In: Motor Klassik . United Motor Publishers, Stuttgart, issue 2/1987.
17. ↑ Micro-Mobility: Smiles n 'more . Retrieved March 15, 2018.
18. ↑ Herbie Schmitdt: Electrical Isetta. In: Neue Zürcher Zeitung . February 23, 2016. Retrieved November 28, 2017 .  
19. ↑ Jürgen Pander: For smooching. In: Spiegel Online . March 4, 2016. Retrieved November 28, 2017 .  
20. ↑ What is the Isetta? In: Der Spiegel . No.  46 , 1955, pp. 28 ( Online - Nov. 9, 1955 ).
21. ^ Fritz B. Busch: His cars, his stories ... and his museum . Motorbuch Verlag, Stuttgart 2003, ISBN 3-613-87262-5 .