Topic: wheel bearing spacer??

[bradshaw106]

i am trying to piece together a set of wheels that came off a cb750.  i was wondering what the purpose of the spacer that is inbetween the wheel bearings in both front and rear wheels?  do I need them?
thanks

[splitt]

Yes, you need them, that spacer is what keeps the bearing races centered in the hub to keep it from binding. If they weren't there, when you either tightened the axle, or a side load is placed on the bearings (like when you corner), there would be problems. At the least, it would force the inner bearing races toward each other causing excessive drag, or at worst the bearings might come apart.

[Markcb750]

When you tighten the axle bolt the stack of components consisting of the outer spaces, inner spacer, inner bearing races, and the rear swingarm ears on the back wheel, form a "rigid" shaft which does not rotate with the wheel.


If the rear inner spacer is not in place the axle nut will not clamp this component stack and the mating components (such as the swingarm) will bend excessively. This is because one bearing floats along the axis (the RH bearing on the rear wheel) and will simply move inward as you tighten the nut without the inner space.

The front axle will not "clamp" at all without the spacer, the floating bearing will simply move inward as the nut is tightened with this spacer absent.