It's a good idea to use a wire brush to clean up the unitbearing where the new rotor will sit. The rotor slides on using the smaller of the two bolt circles. They fit stock JK 5-on-5 and aftermarket 5-on-5.5 lug patterns. The new caliper installs using the original bolts, which should be torqued to 120 lb-ft. Make sure you mount the calipers with the bleed screw on the top. There is a left and right caliper to make sure that this is possible.