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Changing wheel bearings
Originally posted by @andtfoot
There is a few ways of doing this, but this is how I change my wheel bearings; in this case for my front wheel.
The way I do it is destructive to the old bearings (I'm throwing them out anyway...). Do not reuse them after.
To start with, here are my new bearings:
I just bought these from Capital Bearings in Fyshwick. In my case they are 6003-2RSH.
The '6003' designates the bearing size: I should be able to get any 6003 bearings and they would fit.
The '2RS' is the suffix that tells me it has rubber seals. I could get ones with a 'ZZ' suffix for metal seals, or no suffix for an open bearing.
Dunno what the 'H' stands for...
This is also marked on the bearings themselves: on the outer race of at least one side usually.
Obviously, to change the wheel bearings I need to get the wheel off:
In this case I am using an old tyre to rest the wheel on. This prevents damage to the wheel and disc, and provides some room behind the hub. (I do the same thing when changing tyres)
There are probably a few ways of getting the old bearings out, but I use a punch and a hammer:
It is a good idea to use heat in the process to help release the bearing without damaging the hub. You want to be heating the hub so it expands relative to the bearing.
This also helps when putting the bearing back in. Heat up the hub and cool the bearing; I've heard of putting the bearings in the freezer (in a sealed bag to keep moisture out) beforehand for a few hours to assist with this.
What I do is put the punch through the hole and bash out the bearing facing away from from the inside:
What I'm aiming for is this lip on the far side (the inner race of the bearing):
Once this is out, a spacer should fall out as well. Then flip the wheel over and do the same to the other side.
Time to get the new bearing in. Again, there are different ways of doing this. I happen to have an assortment of sockets and conduit that fits perfectly:
It is very important to only use the outer race to get the bearing in. This bearings aren't designed to handle much axial force, and will most likely become stuffed if you use the inner race.
Start it off with little taps to make sure it goes in straight, then bash away until the sound changes (more of a clonk noise as it hits the lip in the hub).
A couple of other ways I have heard to get them in are:
- Remove the guts of the old bearing (inner race, etc) and grind down the outer race to slightly reduce its diameter. Then use this like I'm using the socket.
- Use the punch to gradually work around the outer race, driving it in bit-by-bit. If you slip though, the seal usually gets damaged and the bearing's stuffed.
Anyway after some bashing, one side is done:
Flip the wheel over to do the other side, but don't forget the spacer!
Check that the bearings are seated by checking the spacer between them. It should be reasonably snug. If you have a big bag still, then one or both of the bearings aren't seated right.
Also, do a sanity check and make sure the bearings haven't been damaged in the process. See if they rotate smoothly. If they don't, there is a chance it's buggered and needs to be replaced (wheel bearings are cheap, I usually get a spare for this reason).
Once that's done, put any seals back in and remount the wheel. Don't forget to tighten the pinch nuts and/or brake caliper bolts if you had to loosen/remove them. Make sure your brakes still work and everything moves smoothly before taking it for a ride.