(Boss Ch. 19) Bigger Brakes and Suspension 3.0

In which the track shakedown of my new front end mods (Ch. 18) is a complete success, until my brakes go away and I finally unpack the bigger brake kit I bought in 2017.

Track Shakedown

I spent a recent Saturday at Harris Hill Road with Ryan to shakedown the Audi 90 race car and The Boss. Both cars had recently been extensively reworked to improve cooling performance. The changes to The Boss (bigger oil cooler, better grille) are documented in Ch. 18. The changes to the Audi included: bigger aluminum radiator, race-spec fan, and custom fabricated shrouding.

Both cars passed with flying colors. Before the front end mods, I had seen oil temps on track in excess of 280 F. I logged my temps throughout the day and with the new front end mods, oil temps never exceeded 217 F. I was chuffed! However, on the last two sessions of the day, I began to experience a severe shudder in the pedal under hard braking. In the end, I went to brake for a corner, felt the initial bite, and then the pedal went soft. Old tires were keeping my speeds down, so I made the corner without much distress, but on the back of a successful shakedown, I now had a new problem.

Bigger Brakes

In a July 2014 article, Car and Driver reported, “Ford claims that a 2015 Mustang GT with the Performance Pack consistently beats the lap times of the 2012–2013 Boss 302 in track testing” and in an interview with Terry Fair of Vorshlag Motorsports, ex-Ford engineer Marco Garcia confirmed that, “The goal on the S550 Performance Pack was to be faster than the Boss. That was the baseline and (it) far surpassed that.” That hurts, but progress waits for no one. And now I had another template for track performance.

The Boss came equipped with big brakes – Brembo four-piston aluminum calipers over 14″ rotors, but the S550 PP1 came equipped with even bigger brakes – massive Brembo six-piston aluminum calipers over 15″ rotors. In 2017, a TMO member posted that he was able to fit the S550 PP1 brakes to his S197 Mustang without any modification. They just bolted up. Even better, these were factory parts with Motorcraft part numbers and could be ordered new, often at a discount, from your favorite parts warehouse, rather than paying a premium for a kit from a tuner. I ordered the parts for the “kit” for $1018 out the door (not counting pads, lines, fluid, and spacers), which was an unbelievable bargain.

Brake Parts

FRONT

(1) – FR3Z-2B120-C Brembo Front Disc Brake Caliper, Price: $259.35
(1) – FR3Z-2B121-C Brembo Front Disc Brake Caliper, Price: $273.00
(2) – DR3Z-1125-A Disc Brake Rotor (GT500), Price: $241.16
(2) – FR3Z-2068-C Disc Brake Anti-Rattle Clip, Price: $85.02

REAR

(2) – DR3Z-2C026-A Rotor (GT500), Price: $163.34
(1) – DR3Z-2C100-A Adapter (GT500, right side) Price: $56.93
(1) – DR3Z-2C101-A Adapter (GT500, left side) Price: $56.93
(1) – Blowfish Racing Aluminum Rear Caliper Mount Plates (GT500) – RBM-01-000, Price: $189.99

MISC

(1) – Goodridge 12367 (GT500) braided, stainless steel brake lines, Price: $182.14
(1) – G-Loc GS-1 brake pads (2015+ GT/PP, front), Price: $242
(1) – G-Loc GS-1 brake pads (S197, rear). Price: $124
(1) – Motul RBF600 brake fluid (500 ml), Price: $21.60

OPTIONAL

These parts are to allow clearance of new front calipers under the stock 19″ Boss wheel.

(2) – ARP-100-7722 ARP wheel studs (front, 1/2-20 in. RH, 0.549 in. Knurl, set of 5), Price: $57.06/ea.
(1) – M-1107-B FRPP/ARP wheel studs (rear, 1/2-20 in. RH, 0.614 in. Knurl, set of 10), Price: $131.97
(4) – M-1012-G FRPP wheel nuts (set of 5), Price: $10.97
(1) – 1/4″ 5×114.3 billet aluminum wheel spacers (set of 2), Price: $39.99

TRACK UPGRADES

GT350 Ti Shields
FRPP Boss 302R/S Racing ABS Module

Suspension 3.0

H&R RSS Coil Overs

I chose the H&R RSS Coil Overs, which can lower the car between 1.0 – 2.7″ (F) and 1.0 – 2.5″ (R) and have spring rates of 630# (F) and 515# (R). Compression and rebound dampening are adjusted at the same time with a single adjustment knob, using ratios pre-set by H&R engineers for this specific chassis. There are twelve click settings on the adjustment knob. The dampers are an inverted monotube design and the adjustment knob is located on the bottom of the shaft. The rear dampers are not adjustable.

Suspension 1.0

OEM Ford Performance Springs – 148 lbs/in (F) 185 lbs/in (R)
OEM Boss 302 Ford/Tokico Adjustable Dampers
OEM Boss 302 34.6 mm Front Sway Bar – 436 lbs/in
OEM Boss 302 25 mm Rear Sway Bar – 250 lbs/in

Suspension 2.0

Ford Performance (M-5300-P) “P” Springs
OEM Boss 302 Ford/Tokico Adjustable Dampers
Maximum Motorsports (MM5CC-6) Camber Plates
OEM Boss 302 34.6 mm Front Sway Bar – 436 lbs/in
OEM Boss 302 25 mm Rear Sway Bar – 250 lbs/in
Maximum Motorsports (MM5PBAR-3) Aluminum Adjustable Panhard Bar
Maximum Motorsports (MM5RLCA-52) Aluminum Adjustable Rear Lower Control Arms
Ford Performance (M-5650-A) Lower Control Arm Relocation Brackets

Suspension 3.0

H&R RSS Coil Overs (RSS29170) – H&R Springs: 630# (F) and 515# (R)
Maximum Motorsports (MM5CC-6) Camber Plates
Steeda (555-1067) 34.9 mm Adjustable Competition Front Sway Bar – 440/500/575 lbs/in
Dorman 18 mm Rear Sway Bar – 55 lbs/in
Maximum Motorsports (MM5PBAR-3) Aluminum Adjustable Panhard Bar
Maximum Motorsports (MM5RLCA-52) Aluminum Adjustable Rear Lower Control Arms
Ford Performance (M-5650-A) Lower Control Arm Relocation Brackets

BRAKE PISTON AREAS

Piston Diameters (mm)

05-14 GT: 43, 43
07-12 GT500: 44, 40
13-14 GT500: 38, 34, 30
2015 GT PP: 34, 34, 34

Piston Diameters (in)

05-14 GT: 1.69, 1.69
07-12 GT500: 1.73, 1.57
13-14 GT500: 1.50, 1.34, 1.18
2015 GT PP: 1.34, 1.34, 1.34

Piston Area (one side of caliper)

05-14 GT: 4.50 in^2
07-12 GT500: 4.30 in^2
13-14 GT500: 4.26 in^2
2015 GT PP: 4.22 in^2

Performance Pack Master Cylinder:
Motorcraft 2140(BRMC-218)

S197 MC Bore: 1.063″ (replacement site, so double-check)

The Boss 302 has 4 pot calipers with 2x40mm pistons and 2x44mm pistons for a total piston area of 5554 square millimeters and the 6 pot calipers have 6x36mm pistons for a total area of 6107 square millimeters, which is 9.95% bigger than the 4 pot calipers.