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scott7364
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VBMWMO #7364
Joined: 03/24/2008
Posts: 8

What model is a 32/11 ratio from? Could this hub be used to install a 26/6 sidecar gear ( it has no breather cap). Is there a list anywhere on ratios for various models?

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 4594
Pre 70 gearing ratios

Here's a list of ratios for various bikes:

http://bmwmotorcycletech.info/ringgears.htm

A 32/11 was used on some post '70 bikes.

Another area to check is the VMCA website at:

http://bmwvmca.org/joomla/

Go to the newsletters and look at Vol 2 Number 3. Go to the article titled "Wedgrehzahl". That's a German word associated with speedometer ratios. That article shows the 32/11 ratio might have been used on the R60 solo version.

A 32/11 ratio is 2.91...that's pretty tall and would be used in a solo bike and provides more top end speed. A sidecar drive, like the 26/6 is 4.33 which is a much shorter gear...it gives good torque at low speeds but might limit top end speed.

Kurt in S.A.

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

scott7364
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Joined: 03/24/2008
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Pre 70 gearing ratios

Thanks that's most helpful. Do you know if the "breather" plug on the top of a typical 25/8 or 27/8 is essential? It doesn't seem too effective but...

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 4594
Pre 70 gearing ratios

According to Roland Slabon's book, he says that there were complaints that BMW got regarding rear drives sweating oil...not sure exactly what that means, but likely oil was leaking out past seals, etc. In January 1963 the vent plug was added starting with frame number 657099 on the R69S and other models at the same time (no frame numbers given). It could not be retrofitted.

A caption on a photo says that the seepage was excessive in hot weather. I suspect also under hard usage.

The information was probably taken from the following service bulletin:

http://www.beemergarage.com/documents/200.pdf

I would think it's not "essential", especially if you're just using the bike in a normal fashion and not pushing it on hot days and pulling a lot of load.

Kurt in S.A.

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

scott7364
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VBMWMO #7364
Joined: 03/24/2008
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Pre 70 gearing ratios

Thanks again.

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