Running the stock IMS bearing without the seal...
 

Many of us have seen the video Pedro made showing how at speed an IMSB sitting in oil throws the oil off. He claims that that will leave the bearing "... running dry with very little oil..."
See the last video on this page...
TechnoFix DOF

My understanding is that the IMSB is immersed more than about 25% in oil, more like 50%... but anyway...

While inspecting my IMSB this week I realised that his experiment does not reflect reality. Here is a picture of the IMSB with the flange removed.

http://986forum.com/forums/uploads02...1611277866.jpg

So the outer edge of the bearing is enclosed by the cavity that the flange fits into. with the flange installed there is a space of about 2mm between the bearing and the flange. There is an opening of about 1mm all around the IMS (shaft) that allows the oil to circulate into and out of the cavity. Oil that is thrown off the bearing will not directly exit the cavity it will splash around before some of it exits, while I assume other oil will enter the cavity. The shaft is rotating in the crankcase in oil so there are a lot of forces working to move the oil about.
If I had nothing else to do I would love to set up a test rig to so what really happens, is the oil that exits the cavity replaced by gravity? Does the exiting oil create a partial vacuum that draws new oil in?

... just a sec I'll put on my fireproof overalls...

We all know you're right, Grant! :cool:

That about perfectly sums it up.................

Exactly. Also, the sprocket and the chain are spinning deep in oil so they should splash oil constantly all over, even if the oil level is below minimum. Another thing is, unlike ball bearing applications elsewhere, here the flange, inner ring and race are all stationary, so oil should crawl directly to the balls on the surface of not moving parts. Adding DOF to a ball bearing here makes no sense to me. It`s there already.