BMW R 66
The BMW R 66 is a 1938 to 1941 of BMW produced motorcycle with flat-twin four-stroke engine and shaft drive . As a sports model, it was the sister model of the R 61 , which was designed as a tourer with a side-controlled engine .
BMW had implemented four engine variants in one chassis - R 51 , R 61 , R 66 and R 71 - and thus created four motorcycles in different classes from 500 to 750 cm³.
"The similarity of the engines, such as the use of the same, all-wheel suspension chassis for all four machines, made it necessary to summarize them in just one manual, which at the same time gives an interesting overview of the entire BMW range in the large class."
The R 66 had a foot-shifted four-speed gearbox. The entire drive train was encapsulated against dirt and moisture and, apart from the seldom required oil change, was maintenance-free, in contrast to the chain drives that were almost always unencapsulated at the time.
Rear wheel drive
The rear wheel was driven by a cardan drive with the following elements in the power flow:
- Hardy washer on the output shaft of the gearbox to compensate the angle between the output shaft and the following cardan shaft
- Unencapsulated cardan shaft with universal joint fork on the output side - the visible part of the cardan drive
- Encapsulated universal joint on needle bearings for angle compensation between the cardan shaft and the following wheel drive
- Slidable universal joint fork for length compensation on the input shaft of the bevel gear axle drive
- Input shaft with pinion for driving the crown wheel in the drive housing - power deflection by 90 °
- Needle-bearing driving flange in the drive housing with splines for driving the rear wheel
|Parameter||Data of the R 66|
|Compression ratio||6.8: 1|
|power||30 hp (22 kW ) at 4800 min -1|
|Top speed||140 - 145 km / h|
|Empty weight||187 kg|
|Tank capacity||14 liters|
- Udo Stünkel: BMW motorcycles typology: All series models from 1923 . Delius Klasing, Bielefeld 2008, ISBN 978-3-7688-2451-4 .
- BMW R 66. In: BMW History. BMW AG, accessed on December 29, 2015 (dossier of the BMW Group Archives).
- BMW presents the model series R 51 / R 61 / R 66 / R 71. In: BMW history. BMW AG, February 18, 1938, accessed on December 29, 2015 (document in the BMW Group Archive).
- manual for the BMW motorcycles R 51, R 66, R 61 and R 71. In: BMW history. BMW AG, April 1938, accessed on December 28, 2015 (manual with pictures, 48 pages).
- Spare parts list for the BMW R 51, R 66, R 61 and R 71 motorcycles. In: BMW Geschichte. BMW AG, April 1938, accessed on January 1, 2016 (spare parts list with pictures, 87 pages).
|up to 250 cm³||Touring motorcycle||R 2||R 20|
|Sport motorcycle||R 39|
|up to 500 cm³||Touring motorcycle||R 32||R 42||R 52||R 4|
|R 3||R 35|
|Sport motorcycle||R 37||R 47||R 57||R 5||R 51|
|up to 750 cm³||Touring motorcycle||R 62||R 11||R 12||R 71|
|R 6||R 61|
|Sport motorcycle||R 63||R 16||R 17||R 66|
|Prototypes, racing bikes||R 7|
|WR 750||R 51 RS|
|Military motorcycles||R 12|
|R 75 team|