Fiero Projects
Check out the First Part of my GA brakes from a 89 GrandAm.

Purpose and Reason for the Brakes

    1) Functionality

1.75 inch bigger brakes means more torque to stop the car.

    1) Cool Factor

Just to say I have bigger brakes than most fieros, also to see the brake rotors filling up the space behind the rims.

The Plan

I will fit an 11.75 inch rotor from Wilwood to the front of my fiero. From Wilwood I can buy a hat and a rotor seperatly and get just the offset and size I need. That hat I am getting from Wilwood has the an offset 3/8 inch greater than the 89 GA. The rotor has a slightly different thickness ( 0.81 vs 7/8 ) than the 89 GA rotor. These should fit really easily. The difference in thickness, 1/16 inch, is not a problem short term. I will eventualy replace the 89 GA calipers with Wilwood 4 pot calipers meant for the 0.81 thick rotor. For now I will use the 89 GA calipers and stock caliper mounting bracket plus my bracket.

My bracket will be a simple bracket to relocate the stock caliper mounting bracket out a full inch and inward by 3/8 inch. As you can see from the drawings on the right (click on for bigger image) I will only need a simple flat 3/8 inch steel plate with 4 holes, 2 of which will be tapped. It will mount to the stock mounting side of the spindle.

Thats 20% more torque at the wheels.

I have measured and checked all the clearances and the GA calipers and planned bracket will fit with the 11.75 inch rotor under the stock 15" GT wheels. This should really fill the space behind the rim and look nice.

I will put up more pictures and details as I start. All I need to start is the OK from the wife.

The problem

I have some concern about the strength of the wheel bearings and the increased torque. Even though I can lock up the wheels now, when I am better able to modulate the brakes I will put a lot more stress on the bearings. Ryane Motorsports has always said that the stock bearings will not take the torque of their 12 inch brake upgrade. This troubles me. I plan to eventually get dropped spindles, and at that time I will have a much stronger knuckle and I will no longer worry.

Dispite that concern I am going forward and will be starting this soon.

The second problem

Wilwood does not sell a hat to the measurements that I want. This means I will have to fabricate my own hat. I would be able to do this if I had a welder and a lathe. I don't so I have come up with a better way to mount the Wilwood rotor that I want on to my car. I will get two stock from rotors and turn them down to 7.75 inch diameter I will then drill the mounting holes for the new rotor into the old rotor. I will then mount the new rotor on the old rotor (now a hub hat combination). I have measured it an I am very luck that it put the rotor at the same increased offset that I need to use the simple bracket mentioned above.

The Rotor Specs

The following information from Wilwood's website

Hole Type FAR SIDE I.D. LUG I.D. LBS Part Number
.81" (20,6) 11.75" (298,5) 8 7.00" (177,8) .325 8.34" (211,9) 6.38" (162,0) 8.1 160-0471

Similar brake jobs

The Ultimate Fiero Brake Upgrade (84-87)
High Performance Brakes (88)
Walt Zettner's Brake Upgrade (84-87)


$75.00 x2 Wilwood brake hats
$40.00 x2 Wilwood brake rotors (Ultra lite straight vane vented)
cost of original GA conversion not counted
$15.00 metal for brackets and machining (estimated)
$245.00 total plus tax (estimated)