Wednesday, June 3, 2009

Front Wheel Bearing Project

The front bearings on my touring/commuter bike were making a crappy sound, so I figured, time to look into replacing them.  First step - figuring out what parts to get.  The Shimano web site has drawings for all the hubs with details on the bearings and cones.  However, Wheels Manufacturing cones are sold for a lower price through mail order.  You have to go to their web site and use a cross reference chart to figure out what the right cone to use is.  Bearings are pretty standard and can probably be purchased at your local bike shop.  You can see in this picture, how pitted and ruined the original cones were:
After removing the cones and axles, I tried something new.  I once read about Belgian bike mechanics putting grease ports in hubs to force grease into the bearings from the inside out.  So, with that in mind, I drilled a hole that I could later tap, or jam a syringe into in the middle of the hub with a flexible shaft die grinder:

I then taped the hole over, blew out the drill debris, cleaned out the cups with a cotton swab and applied a liberal amount of grease to the bearing surfaces.  I used lithium axle grease.  If it's good enough for car axles, it's good enough for your bike.

All that grease makes a nice sticky place to put those bearings with a tweezer and make them stay.  After putting in all the bearings, I tightened everything up.  It took me multiple iterations to get the cups and cones not too loose and not too tight.  It always does.  I guess if you're a full time mechanic, you get a feeling for this.  At some point, maybe after 1k miles or so, I'll try injecting grease into the port until it squirts out the sides, wiping off the excess.  I'll let you know how it goes.  Until then, they spin like a new set of wheels and should carry me to work and play many more times.


-d said...

Very nice - a simple rebuild with a drill and tape. It doesn't get much handier than that.

I've always wondered about the viscosity differences between auto & bike grease... here's a pretty good forum:

-p said...

I love it when a chemist or physicist chimes in and shuts up all the shade tree mechanics :-)

I feel somewhat vindicated by that posting.