Hi Andrew,

Thank for the opportunity to help! On the aluminum spindle pinch nuts, there are 2 lines of thought with this part.

1. Some people look at this aluminum nut a see the flanged base and use it without the steel thrust washer.
2. Other people prefer to use the steel thrust washer between the aluminum pinch nut and the bearing because of the concern with the bearings inner race spinning against the soft aluminum material.  That being said, the inner race should not spin on the bearing point.  If id does, there are other problems

I say that if your have enough room in the grease cap to use the steel thrust washer, I would install the Aluminum pinch nut with the steel thrust washer

Thanks,

Andy