Rotor thickness minimum 4-piston KH?

Mattax said
If you have to buy new rotors, get ones where the 'hat' that goes over the hub has been machined. Every time I've checked the castings all seem to be the same - which means the as-cast hat will kiss the pistons boots every rotation. :(
if you find really old stock, that's different. I first noticed this in the early to mid 90s so I mean really old stock.

I agree, my new Bestop drilled rotors needed some grinding on the hat to prevent this, one side only. The ones I pulled with less than 2 years of use did not. Course they were purchased in 1988. Only changed because my braking was never right, my bad as I thought I would change it all. The rotors were never the issue. Still have them Just incase!