rocinante
New member
I know this dead horse has been beat to...death...but humor me please. I am placing this thread in this general forum because while the problem seemed to occur with early 1150 bikes, it has occurred on bikes made both before and after those bikes were manufactured.
This problem surely has a cause and BMW is not explaining that cause, presumably for reasons of liability, but those German engineers are certainly capable of doing the analysis. Let's see if we can do that without them.
1) Misalignment - Some have suggested the shafts were misaligned from the factory. This seems implausible for at least a couple of reasons. First, misalignment would require that transmission case castings were done wrong, but that would cause many other problems of various shafts and parts within the transmission and this does not seem to be the case. Also, the clutch friction disk floats when the pressure plate is released, allowing the splines to line up. At least within a few thousandths of an inch. Far less than the wear we have seen on failed splines.
2) BMW just forgets to lube splines sometimes in manufacturing - This seems implausible also. MANY vehicles with various numbers of wheels use this same basic design and spline lube is generally just not usually a thing at all.
3) Spline Metallurgy - Perhaps certain friction disk hubs were made with allows that were too hard. Perhaps some transmission input shafts were made with too-soft alloys. Or vice versa.
4) Dragging Clutches - Perhaps certain clutches were failing to fully disengage, causing pressure plates to still be dragging against flywheels and pressure plates with the clutch lever pulled. This would put stress on both friction disk and input shaft splines. Riders not engaging clutch levers fully would also do this.
5). Other?
This problem surely has a cause and BMW is not explaining that cause, presumably for reasons of liability, but those German engineers are certainly capable of doing the analysis. Let's see if we can do that without them.
1) Misalignment - Some have suggested the shafts were misaligned from the factory. This seems implausible for at least a couple of reasons. First, misalignment would require that transmission case castings were done wrong, but that would cause many other problems of various shafts and parts within the transmission and this does not seem to be the case. Also, the clutch friction disk floats when the pressure plate is released, allowing the splines to line up. At least within a few thousandths of an inch. Far less than the wear we have seen on failed splines.
2) BMW just forgets to lube splines sometimes in manufacturing - This seems implausible also. MANY vehicles with various numbers of wheels use this same basic design and spline lube is generally just not usually a thing at all.
3) Spline Metallurgy - Perhaps certain friction disk hubs were made with allows that were too hard. Perhaps some transmission input shafts were made with too-soft alloys. Or vice versa.
4) Dragging Clutches - Perhaps certain clutches were failing to fully disengage, causing pressure plates to still be dragging against flywheels and pressure plates with the clutch lever pulled. This would put stress on both friction disk and input shaft splines. Riders not engaging clutch levers fully would also do this.
5). Other?