UK Monster Owners Club Forum - View Single Post

utopia · 21-01-2018, 11:31 PM

Well, that was interesting, and quite fruitful too.
I'm glad I asked.

From the beginning of my discussions with Capo, I had been convinced that there must be a oil supply to the little needle bearing in the clutch end of the shaft bore.
Furthermore, because of the position of the adjacent seal, the oil supply had to be along the shaft from the slave end.
I was also convinced that there had to be both an oil feed and also a bleed/drain hole of some sort.
....but I could see neither.

The penny began to drop when Tim outlined the feed path through the slave end bearing, pointing out that the pushrod o-rings seal on the casing, not the bore of the shaft.
So that was "in" but there had to also be an "out".
I scanned ebay pics of secondhand shafts but could spot nothing there.
Imagine my pleasure when I then noticed the little radial hole clearly visible on the cross section drawing that Capo posted.

To complete the circle, there is also the issue of where the oil goes after it exits the little hole.
This hole looks perilously close to the clutch basket splines.
Hence it is close to being masked by the nearby bearing.
In any case it is too far outboard to exit inboard of that bearing ..indeed an exit path into the clutch case looks more likely .. not good on a dry clutch motor.
So I reckon this hole must line up with a short void between the bearing and its (outboard) seal, and then the oil exits this void through the bearing and into the inner crankcase.

I'm not entirely convinced that centrifugal force is the sole or main driving force for the flow .. though it probably contributes.
So too, but more so I would think, would the static head from the little oil gallery above the bearing at the inlet end.
I kinda suspect that there may also be some sort of surface clingy effect (Coanda ?) going on, and maybe some general creep when the rod moves in/out or spins a bit.
Its also worth considering that some flow from the oil gallery might take place while the bike is parked up.
But then again, the sidestand tilts the wrong way for the oil to go far before having to go uphill.

Anyhow, must say, this is one of the joys of a good forum.
Ta.

21-01-2018, 11:31 PM	#5
utopia No turn left unstoned Join Date: Jun 2010 Location: leicester Bike: M750 Posts: 4,546	Well, that was interesting, and quite fruitful too. I'm glad I asked. From the beginning of my discussions with Capo, I had been convinced that there must be a oil supply to the little needle bearing in the clutch end of the shaft bore. Furthermore, because of the position of the adjacent seal, the oil supply had to be along the shaft from the slave end. I was also convinced that there had to be both an oil feed and also a bleed/drain hole of some sort. ....but I could see neither. The penny began to drop when Tim outlined the feed path through the slave end bearing, pointing out that the pushrod o-rings seal on the casing, not the bore of the shaft. So that was "in" but there had to also be an "out". I scanned ebay pics of secondhand shafts but could spot nothing there. Imagine my pleasure when I then noticed the little radial hole clearly visible on the cross section drawing that Capo posted. To complete the circle, there is also the issue of where the oil goes after it exits the little hole. This hole looks perilously close to the clutch basket splines. Hence it is close to being masked by the nearby bearing. In any case it is too far outboard to exit inboard of that bearing ..indeed an exit path into the clutch case looks more likely .. not good on a dry clutch motor. So I reckon this hole must line up with a short void between the bearing and its (outboard) seal, and then the oil exits this void through the bearing and into the inner crankcase. I'm not entirely convinced that centrifugal force is the sole or main driving force for the flow .. though it probably contributes. So too, but more so I would think, would the static head from the little oil gallery above the bearing at the inlet end. I kinda suspect that there may also be some sort of surface clingy effect (Coanda ?) going on, and maybe some general creep when the rod moves in/out or spins a bit. Its also worth considering that some flow from the oil gallery might take place while the bike is parked up. But then again, the sidestand tilts the wrong way for the oil to go far before having to go uphill. Anyhow, must say, this is one of the joys of a good forum. Ta.