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schrader7032
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VBMWMO #7032
San Antonio, TX
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Is there a place that describes the part numbering system for the prewar models? I've heard that the 11-digit system came into affect after the war but prewar used only 10 digits. I was looking for more explanation on this.

Thanks...

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

Darryl.Richman
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Surf City, USA (Santa Cruz, CA)
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Kurt, it depends on just when

Kurt, it depends on just when you're talking about. From my perusal of parts books, I would say that there were at least three different numbering systems before the war, and two afterwards.

The 10 digit system you mention came in with the R5, I believe, and if I understand it right, all motorcycle specific parts begin with a 2, as it was decreed by government. (They were already gearing up for war, and wanted to get their parts supply chains straightened out ahead of time.) Many R12 parts, when they were upgraded for whatever reason, were also rationalized into this system. Perhaps this is also true for the R35, but I don't know.

Before that, back to the late 20s, BMW specific parts usually included the sub assembly design as the first few digits of a number. So anything that begins M 56 belongs to an engine from the R62, R11 or R12, or their OHV sisters, the R63, R16 and R17. Parts sourced outside of BMW generally have a 5 digit number. Updates or changes are reflected as lower case letters on the end of the number.

For the bikes up through the R52/R57, the numbering scheme is a bit of a mystery to me. The part numbers don't seem to have any strong rule to them for length or division.

After the war, BMW came out with a 7 digit part numbering system, which was used through the end of the /3 series of bikes. These numbers have a 2 digit main group, a 2 digit subgroup and a 3 digit part number.

When the Earles fork bikes came out, BMW recognized that they needed a bigger number space, so they moved to the 11 digit scheme we know and... love... that is in use today. It adopted the main and sub groups from the previous system. The last seven digits are split 1-3-3, and for a while it seems that there was some meaning to how those digits were used, but again, BMW found that they didn't have a enough room and began to just number parts sequentially in this space.

Perhaps BMW didn't expect to be around so long, but even 10 million part numbers began to look like it might not be sufficient for a main/sub group, considering that it covered not only motorcycles, but cars (and aero engines?), too. So, in the 80s and 90s BMW started phasing out parts and then reusing the numbers. There's a story to be told of Mark Huggett going into BMW's system and "saving" many not-yet-reused parts.

This is what I know about the topic; I hope that we can report more authoritatively about it sometime in the future.

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schrader7032
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VBMWMO #7032
San Antonio, TX
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I was directed to this

I was directed to this description by Mark Huggett.

http://www.bmwbike.com/index.php?l=english&n=1&c=2

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

Darryl.Richman
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I would definitely trust what

I would definitely trust what Mark has written about the part numbering systems. A lot of the part books I have reflect later revisions. For example, I have the silver Behelfs-Katalog parts book for the R51/2 and "/3" models, which display all parts as the 7 digit number, but the edition is from 1960. Similarly, the "/2" loose leaf catalog I have seems to have all the updates through 1969 applied to it, with lots of updated part numbers shown.

Even my R12/R17 parts book is from 1940. But in this one case, I wonder how accurate Mark's article is: although there are many parts in this book that start with 212 (eg, 2=motorcycle, 12=model R12), there are also many, many parts that reflect the earlier part numbers, which begin with a design designation, such as M56 or F66 (M56 is the 750cc split case motor originating in 1928 with the R62 and F66 is pressed steel frame originating with the 1929 R11). I believe that this manual was updated with the 10 digit part numbers where reasonable, to accommodate the Wehrmacht requirements.

To support this revisionist idea, I also have a parts book for the R11/R16. If I read it right, this book was issued in March of 1942. It is listed as Edition A and includes the text "3. 42." on the cover; the book covers all five Series of the R11/R16 models -- which is why I bought it, I wanted to be able to understand in detail which changes occurred in which Series -- and therefore had to have been printed after the end of the run of these models in 1934. I suspect that BMW reissued the book because a significant number of R11s had been bought by the Wehrmacht during their rearming, beginning in the early 1930s, and more had been commandeered from civilian use.

What is interesting is that most part numbers begin with a design number, eg M56; many sourced parts are of the earlier 5 digit format; but there are a small minority in the 10 digit format, and these, almost exclusively, begin with 212. Parts for an R11 that specify that they are for an R12? These numbers must have been revised to match the new part number system that the Wehrmacht was using. (I did notice that the hollow rivets used to attach the brake linings to the shoes are listed as a 275 part, so these were updated to match what was being using on the R75!)

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