Need some Disc Brake wizards.

[TobyArnot]

Hey gang,
I'm doing a disc brake conversion on a '70. There is an o-ring of sorts that goes on the caliper bolts and sleeve, between the caliper and the boss on the spindle. I think it has something to do with the "floating" design. Is it necessary? When I put them in, the caliper and outer pad drag on the rotor. Without the o-rings, everything is free. I even tried a thinner section o-ring, but it still wants to drag on the outer pad. Will this center after bleeding and applying the brakes a few times? Don't want to leave them out, if needed, but not real sure.
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Thanks in advance for your thoughts.