With the Steath Bomber’s GT500 front 4-piston Brembo calipers on 14″ rotors, we love the performance and the look. However, our stock 11.8″ rear rotors left us wanting more. Having read about the inter-changeability of the GT500 rear 13.8″ rotor, we researched and found the easiest method to be the NC Mustang Parts adapter brackets. The other popular method is to use the factory GT500 brackets, which requires removing the axles, which then leads into a rear differential fluid change. That seemed a waste, seeing as we had changed our rear differential fluid just a few months ago. The great thing about this swap, regardless of method, is that the GT and GT500 rear calipers are basically the same. The only difference is that certain GT’s have a bit of interference between the caliper bracket and the GT500 rotor. With years of grinding under our belt, we weren’t afraid to make sparks fly to fit this kit.
We ordered the brackets from NC Mustang Part’s eBay store. They arrived quick and packaged well, and included all new hardware. We also ordered a pair of StopTech slotted rear rotors. We then gathered the required tools:
- 1/2″ Electric Impact
- 1/2″ Breaker Bar
- 3/8″ Ratchet
- 3/8″ to 1/2″ Adapter
- 18mm Socket
- 15mm Socket
- 13mm Socket
- 3/4″ Socket (for lug nuts)
- Brake Cleaner
- Matador Surface
- Brake Caliper Compressor
- Permatex Medium Strength Blue Thread Locker
- Bungee Cord (to support the brake caliper)
- 2x Jack Stands
- 2x Wheel Chocks
We began by chocking the front wheels, then jacking up the rear of the car by the axle pumpkin. Placing our jack stands under the axle tubes, we lowered the car onto the stands. Using our torque wrench, we removed the rear lug nuts and the rear wheels. Side note, this is a great time to inspect your wheels for cracks front and back, as well as clean them!
Using our 13mm socket, we loosened the two caliper slide bolts, then hung the caliper from a convenient hole in the inner fender with a bungee cord. We removed the brake pads, then used our 15mm socket to remove the two bolts holding the caliper bracket to the axle bracket. The rotor was then able to be removed. We then used our caliper compressor kit to push the brake piston back into the caliper to make the coming installation easier. Laying the stock rotor on top of the new GT500 rotor, the size difference between them was obvious!
We dry-fit the adapter bracket (which installed with 18mm bolts), then the new GT500 rotor (noting proper orientation of the slots, and using a pair of lug nuts to hold the rotor to the axle flange), then the caliper bracket, and then the caliper. During each step we judiciously checked for proper clearance. Overall, at least 2mm of clearance was present at all points, and the rotor spun free. We then disassembled everything and reinstalled the adapter bracket and caliper bracket using a dab of Loctite blue on the adapter bolts, and proper torque on the caliper slide bolts.
We reinstalled the wheel, then repeated the entire performance on the opposite side. After both sides were completely installed, we removed the jack stands, lowered the car to the ground, and took a test drive to ensure everything was operating correctly. No noises were detected and the brakes worked perfectly. We torture tested the brakes a few days later at the CSCC Fontana Autocross, where they performed great and allowed the car to stay flatter and brake later when entering corners. We highly recommend this upgrade, along with the front GT500 brakes, for any S197 Mustang.