New brake rotor lateral runout problem

[356RS]

Installing new 930 rear rotors and checked the lateral runout, found .77mm on right rear and .46mm on left rear. Specs call for .05mm. Put a pair of standard new rear rotors on to check and found they were at .06mm or less. What gives with the new Zimmerman Rotors?

[356RS]

Problem solved. Nothing wrong with the Zimmerman Rotors. Here's the story and it might help others. I am doing a 930 brake conversion on my 72. Purchased a 930 brake kit from Jeff Gamroth, everything needed in the kit and it's beautiful. After installing the rears I noticed the deep six seem to have a lateral wobble when I spun it. Tried the other wheels, same thing. Checked the rotor and found a .77mm runout on the right, .46mm on the left. Removed the 930 rotors and put the original rotors and found .06 or less. WTF. I started looking/checking at everything. Axle stub, wheel hub, all perfect. I tried installing the 930 rotor without the small 6mm countersunk screws and noticed that the runout was much less, like .25mm less. What I found was the inner ID of the 930 rotor where it mates to the wheel hub had a smaller ID than the OD of the wheel hub. Not by much but enough to cause interference when torquing down. I removed about .5mm of the OD on the wheel hub and everything fits perfect.
Just some information that may help others.

[RWebb]

did you use a lathe?

[356RS]

Yes I did.