Lubricating Hubs

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JJ

Lubricating Hubs

Postby JJ » 3 Feb 2005, 11:54am

Years ago, hubs used to have a little hole that you dribbled oil into, and a clip to cover it up with. Does anyone know if it is feasible to adapt a modern hub in an equivalent way, and if so how?

Specifically, I'd like to be able to push grease into a Shimano dynohub, as they are a pain to service, and a Shimano freehub, which are less so, but still take time.

John

jb

Re:Lubricating Hubs

Postby jb » 3 Feb 2005, 1:28pm

I tried putting grease nipples in to pedals to prolong there life, but modern peddles seem to last a good while without any tampering. Shamano banished lubrication points to the outer edges of the universe a long time ago as they where in great danger of making components last forever, and that would not do.
The big advantage of grease points is that you can remove old lubricant plus contaminants without the danger of introducing new contaminants (a virtually impossible task if you strip the part down, unless you own a steam cleaner, degreasing bath & clean room).
The problem with drilling your own points into the hubs is you have to fill the whole cavity with grease, which can be weighty and cause a slight increase in friction. Where as purposely designed gear would have passages to take the grease straight to point of use. Injecting oil into them would be easier but would need doing more regularly and it would also find its way out causing permanently dirty wheels.

hope this is of intrest

John

CJ

Re:Lubricating Hubs

Postby CJ » 3 Feb 2005, 3:52pm

I do that to all my bike parts, usually drilling and threading so an M3 screw can be used as a stopper. But for slim-bodied road hubs I bought a load of Morningstar hub-buddies before they disappeared off the market. And a quick-and-easy hole-cover for fat hubs is a short section of PVC waste pipe, slit to pop over.

There is a small weight penalty of course, but very small even in the fatter mountain-bike hubs. Friction is nothing to worry about. The weight of the valve still turns the wheel and bike hubs rotate far too slowly for grease viscosity to consume a significant amount of power.

Dripping oil in is no good. Bike hubs are mostly designed for grease lubrication, so oil runs out too fast and seldom provides even a temporary barrier against the ingress of water and grit.

For 2005 Shimano Deore LX and Ultegra freehhubs feature internal grease sleeves and front hubs have O-rings to keep the grease around the bearings. With those it'll be necessary to find a new route for introducing fresh grease, but if possible that'll avoid filling the whole cavity. These models and several others will have double contact seals protected by outer labyrinths, so although the actual bearings are cup and cone (most sensible for lightweight bike parts because this design can tolerate some misalignment) they'll be better protected than most so-called sealed bearings. They might even work with oil instead.

Unfortunately I don't think any of this is applicable to their hub dynamos. That would be too much volume to fill with grease, viscous shear in which would cause excessive drag if it were to enter the narrow gap between magnets and armature, quite apart from any interference with electrical performance due to the different magnetic permeability of grease compared to air. Shimano's hub dynamos really do need those internal grease sleeves, but so far as I know, none of them have got one yet.

JJ

Re:Lubricating Hubs

Postby JJ » 8 Feb 2005, 1:42pm

Thanks for the advice. Looks like I'm into dismantling the non-serviceable right hand bearing on the dynohub then! Drilling my other hubs seems a good plan though.