I am doing the Grand Am brake swap on all four corners. I do not want to machine the front hubs. Can I machine the rotors to fit inside of the front hub instead of machining the hub?
Thanks!

I'm not sure what you're asking. The '84 to '87 Fiero front hubs, bearing carriers, and rotors are a single, integral casting. You need to machine the rotor portion off the casting in order to make way for the GA rotor. Once the Fiero rotor has been machined off, you're left with the 5 X 100 mm lug flange and bearing carrier portion of the casting, which you then slide onto the spindle and secure it as you would if it were all still there. Lastly, the GA rotor, which is simply a brake disk, slips onto the flange and wheel lugs. That's why the Fiero wheel flange has to be turned down to a specific diameter as well... it's to fit inside the GA rotor mounting flange.

I guess I don't know what I need to have machined off then. The center hole of the brake disc brake is too small to fit into the fiero hub. Correct? If I machine the center hole of the brake disc larger so that it fits onto the hub, will this be the same as machining the hub? Also the outside diameter of the hub must also be machined down? Is this correct as well?

No, the problem is the Fiero hub is built into the Fiero brake disc, it's all one piece.

Have a quick look at the two pictures in this link. http://fierozone.tripod.com.../lathecut/index.html

The first picture shows a machined Fiero hub on the left, ready for the GA rotor upgrade except that the wheels lugs have been removed, and a stock Fiero rotor/bearing carrier/flange on the right in the same photo.

The second photo to the right shows the machined down Fiero hub and a Grand Am rotor. You can see why the Fiero hub needs to have the Fiero rotor machined off and the hub machined even further to fit inside the GA rotor hat.

Thanks!!! I have not worked on the front brakes in a while! So I need four front calipers, two sets of front brake pads, four front rotors (all for the 1989 Grand AM), and to turn the hubs on my lathe so they accept the GA rotor like on the rear of the car? Then maybe a grind here or there? I am sorry that my question was dumb; I didn't remember the front rotors being the hub assembly!
+1 for you guys!

Yeah, that's right. The year 1989 will work, they're the same rotors and calipers that were used from '85-90. All you'll need to do afterwards is a little grinding.

Definitely a worth while upgrade.

I did the Grand am brake upgrade, so when your ready to grind the Caliper brackets, your going to have to remember to look down at the backside after everthing is put back together (wheels are still off) and make sure the bracket isnt touching the rotar,if it is, then you need to grind a little more off (I used an angle grinder for that).

[This message has been edited by James Bond 007 (edited 11-28-2011).]

Here is mine when I did it to my Sport