A Muzi said:Quoted message said:Why would grease "dry out" differently inside a fairly well
sealed tub and inside a fairly well sealed hub?
By whatever process, grease in hubs does indeed lose its oil
, leaving the dried crusty soap. There is more of a vent
than a plastic tub affords.
Dear Andrew,
So it's the slight but steady venting through the imprefect
seals that lets grease dry out?
What I was wondering was whether it was a couple of other
things.
Heat degrading the grease and cooking off volatile oils
seemed unlikely, since I doubt that it gets warmer than the
metal hub, but then we're heard about the point contacts of
steering head bearing micro-welding and fretting if they
lose lubricant, so I wondered about tiny local heating.
Churning and aerating the grease seemed more plausible,
since the balls slide in endless circles through the soap.
I also wondered about water leaking in and emulsifying the
grease into the odd gray mess that I see on my chain after a
rainy ride and then seeping out, carrying the lighter oils
with it.
Since I've got someone with a fair amount of experience
handy, what are your thoughts on grease versus oil in a hub?
After five years or ten or whatever the dry-out period is
for grease in hubs, would you expect the oil to have dried
out sooner, later, or roughly the same?
Thanks,
Carl Fogel