I have a 89 Firebird Formula with the WS6 package
Bought the car second hand the rear rotors are larger then fronts, this doesn't seem like it would be right?? I believe someone put smaller rotors on the front of the car and cast iron single piston calipers on the front. Any idea what my stock rotor size should be on the front? Should there be aluminum dual piston calipers on the front if the package came with rear aluminum rotors. The car isn't stopping the way it should even with a solid pedal.

 

1989 was the year that the rear brake rotors were upgraded. You have :
Front 10.5 dia rotors & single piston iron calipers.
Rear 11.655 dia rotors & single piston aluminum calipers.

No one screwed with your brakes rotors, they are the stock sizes.

 

I know, I know. Doesn't make sense, but this is GM we're dealing with after all. The front up-grade (I went with 1LE's at all four corners) is simple.

JamesC