My Budget 11" Big Brake Kit….. Installed on 90 Mazda Miata w/ 15 wheels.
2 1990-1991 Corrado front rotors – Napa part # 4886122
2 Front rotors from Miata (used to make hubcentric rings)
1 Front / Rear set of your favorite brake pads for a 1.8L Miata
1 Wilwood Proportioning valve – 260-8419
4 Grade 8 flanged bolts to mount caliper bracket
4 Grade 8 all steel locking nuts
4 M12 bolts to mount the 1.8L caliper brackets (original bolts are incorrect grip)
1 ¼ chomoly plate steel for caliper mounting plates.
2 1.8L Miata Brackets ( for those with 1.6L brakes)
Step 1: Make hubcentric rings and turn down head of 2 Grade 8 bolts.
Take a new rotor and a pair of old rotors to someone with a lathe. Bribe them to cut rings from the original rotors that fit inside the new Corrado rotor. Also, have them cut the head of the bolts down to fit under the caliper brackets (see picts) You may need to clearance the caliper bracket to allow the most material for head bolt.
Step 2: Ream/drill the caliper holes on spindle to fit the new Grade 8 bolts.
Step 3: Cut out mounting plates using downloadable pattern. Drill the holes on a drill press only. I would start by drilling 2 of the holes to size, 2 slightly undersize, then mount on spindle and ream to final size for a secure fit. Alternatively, If anyone wants to put this in AutoCAD step up
Step 4: Mount bracket to spindle, bolt rotor to hub, mount caliper bracket. Check fit between both faces of rotor and bracket to rotor OD clearance. They should be even. If not, determine why and correct.
Step 5: When fit is good re-assemble and torque with green locktite.
Step 6: Install Proportioning valve. Bleed brakes, set front to rear bias and enjoy.
Disclaimer – this is provided as educational only. If your brakes fall off this is not my fault. Do not attempt if you are not skilled in this area – get help.