I just went through this on my S4 brakes. By trying to center it up on the stock 930 rotor, I ground one side about 1/8" front and back (along with the button head screw. I then realized that this is what supports the brake pad and felt that if the pad went too low, it would cause a problem. OK, the pad would have to be really at minimum, but...

Now if I could just get the new dust seals in, I would be ready to install them finally. It would have been nice to test them at VIR 2 weekends ago also.

 

Here's another close up of the modified throat.

 

A930Rocket:

Since I'll widening the throat to fit a wider rotor instead of trying to center the caliper on a rotor, the space between the rotor and the clip to hold the pad won't be wide enough to fit the backing plate through. So I should have no worry there.

I'm starting to get restless now that some people are already back on the track for the summer. My first event isn't until mid June. Of course, that's because I still have a crap load to stuff to do to the car and it won't be ready until June

Now, were did I put that grinder...