Since the hub/rotor in the original 64-72 is not 1 piece it makes it very difficult to alter. Generally a machinist would just rotate the hub and drill new holes in between the existing studs. On the 2 piece hub/rotor there is no material in that area so the only way to do the change is to weld up the old holes and redrill them. The wheel studs actually hold the hub and rotor together. Material has to be added behind the hub as well.This makes the hub very hard to drill. In addition when the bolt pattern is widened it necessitates adding more material in the stud area to support it. I gave this a try to start with but most shops wouldn`t touch it. One shop tried it (reluctantly) and before it was done they gave up on it, saying it was not going to be worth it. Moser used to have a machine just for these 2 piece assemblies but the room it occupied was worth more to another machine (since there`s very little call for it anymore) so they removed it in favor of a more profitable piece of machinery. I`m all for keeping things simple and the cost down and thus far this is the cheapest method I`ve found. Anyone who`s been down this road knows that choices are very limited in what you can do with this 4"bc KH disc brake sytem.340mopar said
