The History of the R12 Head light

During the long production time of the BMW R12, Bosch was steady renewing its products. This is why we find different types of headlights on our BMW R12 machines.

In 1935, the year when the R12 / R17 came out, Bosch presented a new Type of headlight. The “EAS” Headlight which was called “Spitzscheinwerfer” because of the pointed long backside. With this design a new section of the Bosch Headlight products in the BOSCH family was introduced. They had products used on motorcycles, cars and other vehicles until and during the World War 2 and it affected also the headlight design after the war for a very long time, especially on motorcycles.


The larger machines like the R 12 and R1 17 received a Bosch EAS with a light dia of 170,0 cm, this was called the EAS 170×2. The x2 did stood for the two attachment points on the left and right, these were for motorcycles .

A new feature on the BMW R12 in 1935 was the speedo. This was integrated in the Headlight on this model. But as you can see on late Series 5 of the R 11, there have been also EAS 170 without this hole for the Speedo. Also on the NSU Kettenkrad and other Machines the EAS 170×2 without the Speedo hole could also be found.

The first two types of this headlight on the 1935 R 12 and R 17 had a 4,0 cm diameter hole for a little Veigel Speedometer with scale drum which spins when moving.

The main difference in this two versions of the Headlight, as you can see in the picture out from the first parts catalogue from May 1935 , was depending on the equipment of the motorcycle. This was a battery Ignition and magneto.


The R 12 appeared in different Versions. The customer could choose between a batterie Ignition and a permanent magnet ignition system, both produced by Bosch. The Batterie generator model was called B245 RS108. It was advertised as a sport version and was mostly combined with a two-carburetor version for the R 12 like that on the R 17. For the magneto version the Bosch D2B 167 RS was used. Later this version of the magneto was updated to the D2B RS 170 and D2B RS 171.

If the motorcycle received the B245 RS108 it also received the EAS 170×2 with a charging light and a overvoltage fuse. On the magneto version this was not needed thus you don’t have anything on them.

Inside, main difference between the two Versions was the power switch. The wiring of the whole bike is a bit different.


One example of the small Veigel drum speedo in an EAS 170×2 for the magneto Version on an R 12 that was grey painted for German military use

An empty housing of the Batterie ignition Version on a civil black colored and chromed EAS 170×2.

Today the small Speedometer version is seldom and hard to find in a good shape. In the years 1935 and 1936 there was a low number of R12 motorcycles in proportion to the total amount. Another reason is the fact, that later models had not this 4 cm drum Speedometer.

In the end of 1936 and the spring of 1937 the model of the speedometer was changed with a new and modern version with a 8,0 cm diameter. The date of change is flowing and comprehensibly on historical pictures. The parts catalogue was changed and expanded with the new version in October 1937, but the Illustration stayed the same until latest version of 1942.

The drum speedometer has been out fashioned and Veigel did come up with a new speedometer pointer.

With the new speedometer the EAS 170×2 become a new wider speedo with a 85mm hole. Here is an original EAS 170 light for the BMW R12 to be used with a D2B magneto from BOSCH. Also to note is the original Veigel speedo.

Example of the large 85mm Veigel speedo in an EAS 170×2 for the magneto version of an R 12 that was grey painted for german military use. The speedo faceplate is the military and is a left side cable entry for the high low switch.

The Batterie ignition Version on a civil black colored and chromed EAS 170×2. The speedo faceplate is civil right side cable for the high low switch

Another difference was the small hole where the cable for the high low switch goes into the light. The high low switch of the light was always inside the Headlight of the EAS 170×2. Depending on the armature types the hole for the cable was on either the left side, or the right side.

This original picture from the handbook of May 1941 shows the EAS 170×2 from the inside (military machine). Here you can see the flexible speedometer shaft in raw metal, the cable for the high / low switch on the left side, EAS 170×2 reflector with a small gab on the backside to light up the speedometer when the lights are on.

Original BOSCH key with the logo under the key.


Original BOSCH headlight ring

Original BOSCH glass.

The light switch is a very complex design that must be treated with care. The break down of this is easy to understand. From the BOSCH factory manual we break it down again.

  1. Metal shroud
  2. Metal bands that hold the bearings in
  3. The key switch
  4. Bearings which hold the key in place when depressed
  5. Spring
  6. Plastic insulator
  7. Metal contact tab
  8. Plastic detent
  9. Switchboard

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