70 Dart Kelsey Hayes rotors

Have a look at this:

Restoring and tweaking 4-piston disc brakes

The key bit of info:

Factory literature of the period stated emphatically that these rotors were not to be machined thinner, but replaced if the grooving made the rotor unuseable. Research has uncovered the reason for that statement: the factory had little confidence in the ability of the lathes then in use to properly maintain runout and thickness variation specs, which are:

• Minimum thickness: 0.750"
• Maximum TI.R.: 0.0025
• Max thickness variation (parallelism:) 0.0005"

Today, however, every garage has equipment capable of easily maintaining those tolerances, so machining is now considered acceptable.

This article is from almost 30 years ago and things have come full circle because today, every garage that had a brake lathe has gotten rid of it since nobody bothers turning rotors anymore!

I have to decide if I'm going to search for a local garage to machine my KH rotors, or just bite the bullet and install the 73+ front end I have sitting in my shed.