Re:450 foreman rear axle bearing ?
The fix for the left is a bearing, a seal, and a close examination of the hub to see if there is a groove worn in it where the seal rides. If there is a groove, the mud will go right under the seal...
You've gotta unbolt the left shock for this, as there is no effective way to remove the bearing without removing the left axle tube. Make sure to support the back of the main frame (rear of the engine...) before unbolting the shock.
The right side (brake side) is just as easy to change, but a little different. You've got to take the brake drum off, then the brake backing plate has to come off. Leave the shoes on it if you wish, but the rest has to go(Two cables, one vent, four nuts hold it to the axle... and remove the brake backing plate right over the axle just like the drum cover and the drum came off...). There's a circlip on this side that holds the bearings into the brake backing plate before they can be removed. There's two on this side, not just one. I would change them in pairs, but I'd spin them by hand first before I removed the clip. Diagnosing anything except brakes on the right side by noise alone will usually result in a misdiagnosis.