Brake caliper???

Putting together a Black diamond 18. I run 3/8 wildwood rotors and wildwood baa 120-11571 calipers. Went to mount calipers and the brake mounts on the front of the spindles are right in line with each other. Won't slide beside mounts to fasten bolts. Ran this same set up on blue gray spindles. These spindles are TWM and had .810 wrote on them. I would think the centerline of the rotors would be in the same spot? Measured the deference and the brake mount on Black diamond spindles are 3/8" closer than blue gray spindles. Any ideas what to do to make work?

If I understand what you are saying, the centerline of different thickness rotors is different as well. The outer surface of the rotor is basically inline with where it mounts to the hub. I've never had either of the chassis brands you mention, but if the spindle is stamped .810, it's fair to assume it's for those thickness rotors. MasterSbilt used to ask what thickness rotors you had when you got new spindles, but I know some manufacturers are now building them all for the thinner rotors, then using spacers between the caliper and spindle for the 1.25" rotors.

I know that doesn't help your situation, but that's my take on what you've got going on.