Reply to "Question for those who are familiar with the European GTS"

Yes. The Borg-Warners on the Fords are that way until the end of the '67 model year. They don't use the spacers in between the halves to adjust for rotor thickness though.

I suppose that spacer on the Girlings could be cut out of aluminum plate stock and save a pound or so on the complete assembly?

What year is your car? Is it a GT5? Those are some hefty rotors?

Cars this size and weight would never need a rotor that thick for street use. The thickness doesn't add to the stopping ability of the design. The thickness is there for greater cooling capability under heavy race conditions since the venting is so much more substantial.

That's why the rears on the US market cars were solid rotors.

As a matter of fact, it is doubtful that the Gp3, 4 or 5 brakes in the front have any more braking torque than US cars do? That is determined really by the leverage that the caliper has on the rotor and that is changed by increasing the diameter, the radius or lever arm on the center of the hub.

On a street car, the big brake are really for show more than anything else.