Well, I'm up to date on the whole mid-season switchover from composite to cast rotors for the '99 XJ. I'm also familiar with how to tell them apart. Hat height, overall height, thickness of hat mounting flange, etc.

Here's my dilemma:

The rotors that came off my truck, when laid flat, measures 3 1/16 inch from the table to the top of the hat. The new ones I bought also measure this. So far, so good. But... the mounting flange thickness (hat thickness where the studs come through) are very thin - approx. 1/8 inch - on my old rotors. The new rotors have the thicker 1/4" flange.

So, the way I understand it, the composite rotors have the thin flange. The cast rotors have the thick flange. But heights don't add up if I do that. It's like I have the right hat height, but wrong thickness. Does that make sense?

Emrah