Speed W Numbers and Rear Drive Ratios

Hiya - I searched the MOA forum a bit, sorry if I missed a prior post, but I am looking for the list that matches rear drive ratios with "W" numbers in the speedo unit. I have a 1973 R60/5 with a 37/11 rear drive. Not surprisingly, the odometer failed. I read Snowbum's articles, and some ABC tech stuff, and he nicely calculates a theoretical "accurate" ratio - but I am looking for what are the actual W numbers BMW put in the bikes ! Thanks in advance....tough to read the speedo head stamping on the /45 unit but it "looks" like 1.215, assuming the German "1" looks sort of like a funny number "7".

This discussion by Snowbum?

http://bmwmotorcycletech.info/ringgears.htm

Not surprisingly, the odometer failed.

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What do you mean by that? Having any given speedometer hooked to a bike, even if it is the wrong ratio, doesn't necessarily mean it's going to fail.

even if it is the wrong ratio, doesn't necessarily mean it's going to fail.

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And . .. . according to the guys at Palo Alto Speedo, the intermittent shock loads caused by a bunged-up drive cable can cause instrument failure...

They're old instruments. I just had mine rebuilt too.

the German "1" looks sort of like a funny number "7".

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Hence the reason for the slash...

Lmo1131 said:

And . .. . according to the guys at Palo Alto Speedo, the intermittent shock loads caused by a bunged-up drive cable can cause instrument failure...

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I agree with some malfunctioning equipment. But the OP seemed to suggest that running a rear drive not compatible to the speedometer ratio would cause it to fail. Even it were the correct ratio, a bad cable can still break something.

If that is an original (unmodified) speedometer, it should have a W1244 (1.244 on snowbums article) code if it is in miles per hour and calibrated for 3.36:1 findal drive ratio. That indicates the input cable turns 1244 revs per mile.