The Pontiac Fiero 12" Corvette Brake Upgrade Bracket Adapter Set consists of (2) front adapter brackets, (2) rear brackets, and (4) concentric rings.
These brackets will allow 1985 Corvette front calipers to fit on the 12" rotors, and 1988-96 Corvette rear calipers to fit the rear.
The tapped holes for the front brackets are M-12 x 1.5mm. This is the same thread used other places in the brake system.
When changing over to the Corvette brakes, 12 inch stock Corvette rotors are used in place of the small, non-vented Fiero ones. The rotors have a different I.D. (inner diameter) than that of the Fiero's. This presents a problem as the rotor I.D. is designed to barely fit over the hub, so that it is perfectly centered, avoiding clearance problems with the caliper.
This fit also makes sure that there is not any side load on the lug studs. Finally, a non-centered rotor would have the same effects as a non-balanced wheel (noise, vibration, and possibly excess tire wear).
To correct this problem, concentric rings are needed to fit over the hub and match the I.D. of the Corvette rotor.
Click here to download a dxf of these pieces.