In order to provide clearance for the caliper you will need to grind a little material off of the knuckle. With the caliper mounting bracket on the spindle you can get an idea of how much grinding will be necessary to fit the caliper. Remember that as the pads wear out, the caliper will move inward because of its floating design. If you don’t grind enough, your caliper may hit the knuckle and render your brakes useless. We ground the fill plug for clearance, although you could just replace the plug with a flush-mount one. Now you can start grinding the knuckle between the two bolts that are furthest to the back of the knuckle. You don’t have to remove a ton of material, but make sure you have good clearance by periodically replacing the caliper mounting bracket and caliper for test fitting.