I've got an Eric Shea v-caliper kit, and 911 rear vented rotors. For the caliper to fit, 4mm has to be taken off the radius of the rotor.

I'm wondering if I can make an adapter to move the caliper 4mm outward, so the rotors will fit un-modified. I don't like having to have my rotors machined every time I change them, and they're also balanced using divots in the edge. The balancing divots would be mostly/totally erased if I take off 4mm.

I realize it wouldn't be easy... I'd have to move the hole for the inner adjuster, and maybe move the parking brake cable mount. Is there anything else to consider that I'm not thinking of? (there seems to be plenty of clearance between the caliper and the inside of the wheel)

I suppose you could make an adapter to move the caliper 4mm out and 4mm back to eliminate using the spacer under the rotor, and turning the rotor down. On the other hand, buying a set of 914/6 GT rotors would then seem to be cost effective.

I've already got the rotor spacer, and I'm needing to space the wheels out anyway, so that's no problem.

Wouldn't spacing the caliper out also increase braking effectiveness? (clamping the rotor farther from the center of rotation)

I didn't even know 914/6 GT rotors existed.. how much are they and where do I get them? I assume they are just a vented version of the 914/6 rotor?

Yes, moving the caliper out would be good for braking purposes. However, the increased inertia makes acceleration slower and stopping would mean more energy dissipation; that is the flywheel effect. The big deal is how you go about moving the caliper, and the cost involved to do so.

I don't recall the price I paid for the rotors now, but it was from a club member. They are probably still a dealer item. Yes they are a cross between a 911 rear and a 914/6 rear; and unique unto themselves.