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schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6540

I noticed that some of the numbers for the pre-war bikes don't add up and was wondering what happened when assigning the numbers. For example, there were 15386 R35s produced but sources show the following:

- Frame -- 300001 thru 315654 (that's 15654 consecutive numbers)
- Engine -- 300001 thru 315387 (that's 15387 consecutive numbers)

So, one more engine was built and an excess number of frames were built. Why publish the numbers for bikes that apparently were never built? What happened to all those extra frames?

I also saw that the R51 and R61 share the same range of frame numbers -- 505001 thru 515164 (10163 consecutive numbers) -- while the R61 adds another range of frame numbers to that -- 607001 thru 607340 (340 consecutive numbers). But only 3775 R51s and 3747 R61s were built.

Using the search tool on the left side of the screen, frame 505001 was used on four bikes -- R51, R61, R66, and R71. The total produced for those four bikes is 12649. Obviously additional frame numbers were used as indicated above for the R61.

So, is that why I've read that certain parts, etc., can be used on several different bikes, making is easier to try and assemble a numbers-correct bike? I suspect also that BMW can't tell us which of the four models frame number say 509001 was used on?

My head hurts...

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

Darryl.Richman
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VBMWMO #6285
Surf City, USA (Santa Cruz, CA)
Joined: 10/27/2006
Posts: 2185
This era in BMW's history is

This era in BMW's history is pretty confusing. From 1938-1940, BMW made four plunger frame models: R51, R61, R66 and R71. They all used the same frame and rarely if ever did the frame numbers, which were in the same range as the R51 engine numbers, match. The R61 and R71 continued to produced for the war effort, and these engines and frames did match.

If you add up the early bikes, there were 10,081 engines of all four models produced, and there were 10,164 frames in the 5xxxxx number range.

BMW can often tell you if the frame and motor in a non-matching numbers bike left the factory together. If they did not, BMW will tell you about each part but will not tell you what the matching halves were. You'll find lots of "bitsas" floating about, especially R35s and R12s (same issue there, and the R35 has the further problem of continuing to be built in East Germany after the war).

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Matteo
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VBMWMO #7805
Joined: 04/12/2010
Posts: 171
BMW database is by engine

I have a R51 frame and two r51 engine cases, one in poor condition with a number stamp and one without a stamp. BMW archives gave me detail information on the engine, but was not able to say anything on the frame (they were not a matched set). I politely asked if they had any information and several days later they told me that the frame was delivered in the summer of 1938, but that is all they can say because their database is based on the engine number. I was also told that they have holes in their records during this era.

BMW archives is a great resource and a great group of people.

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