manual pic, #13 [called grease deflector], it's a flat donut shape with a slight lip on the outside, fits against the backing plate ... the inner bearing [#11, your "large bearing"] should be fit into the back of the hub with a seal [#12] to hold it there, it is NOT independent of the hub, the dust cup/ grease deflector is .... with the way you state it, like cren said you may not have had the inner bearing seated properly, as well as having a missing dust cap in back .... and now you need to check that spindle well to see how badly it's been scored, they can break after that kind of abuse
Bill
