Vintage BMW Motorcycle Owners

More fun reading.

Lee

Thanks Lee ... others readings for the evening! Beautiful!
Luigi

So there was a oil filter of sorts used back then. Replaced every 7500-10,000 miles. Must have been a helluva filter for the times.
Did they also use slingers of some type? Why did they stop using filters by the time the /2 came along?

twocams

The R51/2 had slingers. And since the R51/2 was more or less a reverse engineering of the R51 from before the war, I'm guessing the slingers were used extensively in the 1930s. I had no idea that any BMW prior to 1970 had a filter. I wonder if the case for eliminating it was that other parts of the engine would fail long before the filter would provide any help, so then why keep it...it meant extra engineering. What type of main bearings were used? I thought the need for filters arose because of the plain bearings that were used in the /5 which required high flow clean engine oil. The /2s have roller bearings.

In the case of design changes, the early days of airplanes were not designed with structural elements that could last thousands and thousands of hours. So, while parts had to be strong, they didn't need durability since the aircraft were prone to breaking/crashing long before that.

"aircraft were prone to breaking/crashing long before that."
I found this to be funny...but so true. those were the days.

twocams

The R12 has ball bearing mains and roller bearing big ends, an oil feed supplies each main bearing and the big end bearing via drilling’s in the crank. The main oil feed pipe also feeds the timing chain gear and a fourth outlet goes into the filter. The filter can in theory get 25% of the oil flow. So all oil should eventually flow through the filter.
This drawing shows the detail.