I don't know if the 450 is the same, but on my 300 the inside of the knuckle where the bearing sits was actually worn out enough to the point of where the bearing can move just slightly, causing them to wear out very quickly. It would wear the bearings out in about 3-4 weeks. I changed it out, and now the bearings have lasted probably 4 months and aren't even getting any play in them yet. Like I said though, the 450 could be different, but I'd imagine it has a fairly similar setup. Hopefully I was of some assistance. Later