Jim Smart
September 23, 2016

It is impossible to believe the redesigned S550 Mustang is now entering its third year of production at Ford’s Flat Rock, Michigan, assembly plant. The most advanced Mustang ever produced is factory fitted with the largest disc brakes this breed has ever had. When you mix in a powerful 3.7L DOHC V-6, 2.3L EcoBoost, or the awesome power of Ford’s state-of-the-art 5.0L Coyote Ti-VCT V-8 in the GT, cruising and weekend racing have never been better.

Wilwood Disc Brakes is two-thirds of a continent away and has concluded that with all this power, the Mustang’s binders need to be larger and more responsive. The time-proven Southern California brake manufacturer has developed wide-body aircraft-sized Aerolite 6R 15-inch six-piston front disc brakes and Aerolite 4R 14-inch four-piston rears for the 2015-2017 S550 Mustang.

The forged aluminum Aerolite radial mount calipers and big-diameter Spec37 alloy directional vane two-piece rotors are employed into these all-new disc brake upgrade packages for the 2015-2017 Ford Mustang. The Wilwood front kits feature Aerolite 6R six-piston calipers with a choice of 14- or 15-inch rotor diameters.

Wilwood rear Aerolite 4G kits feature the MC-4 mechanical parking brake calipers at the 12 o’clock position over 14-inch rotors. Front and rear kits can be style-matched with either gloss black or red powdercoated calipers and with a choice of either SRP series drilled and slotted or GT competition series slotted face brake rotors. What’s more, BP-10 compound SmartPads are included to provide a brute high-performance response for the street or strip. Simply said, you can enjoy these Wilwood Aerolites for the commute or on any race course.

The new Aerolite kits have been set up for matched performance with the factory Ford master cylinder and are fully functional with the ABS and all electronic controls. All the necessary hardware, DOT-compliant braided stainless steel flexlines, and parking brake cable kits are included with a detailed installation guide for a fully bolt-on installation.

We decided to visit Wilwood’s R&D lab and bolt a set of these Aerolites onto the company’s 2016 Mustang GT test car. We were able to accomplish this task in a morning and be ready for action by afternoon. And speaking of action, Wilwood decided to upgrade wheels and tires for great looks and improved contact patch with huge, 20-inch M147 10-spoke Niche Essen wheels and Falken Azenis FK453 radial tires. What this has meant for the Wilwood S550 coupe is exceptional handling and extraordinary braking for any driving environment. Drive it to work. Play in it on the way home.

01. Ford gives S550 Mustang buyers a lot of brake for 2015-2017 with behemoth 13.90-inch discs in front straddled by bone-crushing four-piston calipers. Wilwood shows you how to do it better and with less weight.

02. The stock four-piston caliper is removed and supported temporarily until brake lines can be disconnected and replaced with Wilwood braided stainless steel hoses.

03. The stock brake rotor, which hangs on a sealed hub, is removed. Nice thing about sealed hubs is you never have to pack wheel bearings again.

04. The dust shield is removed next using a 13mm socket.

05. Check out these big 15-inch Wilwood 6R Aerolite front disc brakes with six-piston calipers. These massive AERO 6 calipers are Wilwood’s newest design engineered for big braking capacity with large-diameter rotors for heavy-duty performance. We are talking big brake performance for show, commuting, and racing. The 140-13887 kit is fully compatible with OE master cylinder output and ABS function. Staggered and directional vane 15-inch rotors provide maximum cooling for sustained high-heat durability. These guys will stop you.

06-07. Aside from the obvious advantages of Wilwood Aerolite disc brakes there is the weight advantage. Both rotors and calipers are lighter. The 13.90-inch Ford rotor tips the scale at 28.2 pounds. The Wilwood rotor comes in at 20 pounds.

08-09. Hat and rotor go together next. Bolts get torqued in a crisscross fashion to 155 lb-in. (That means pound-inches, not pound-feet; it is an easy mistake to make.) You may use Loctite 271 on the bolt threads or safety wire the bolts if you are going racing. You will want to use 0.032-inch stainless safety wire to secure the bolt heads. And by the way, good safety wiring takes a lot of practice. Wilwood shows you how in the instructions.

10. The brake caliper bracket is mocked up where the rotor and caliper are mounted and checked for clearances. Shims (arrows) are used to position the caliper. Wilwood suggests beginning with two 0.033-inch shims on each bolt, then tightening and checking clearances. You must use the same number of shims on each bolt. This bracket must be tightened square against the spindle, also known as the upright.

11. Pay strict attention to these dimensions during brake mockup. A minimum 0.080 inch of clearance is allowed between the wheel and caliper. All brake dimensions and clearances are shown here.

12-13. Once you have ascertained the number of shims needed (if any), you are ready for permanent installation. Use Loctite 271 on these bolt threads and tighten to 60 lb-in.

14. Caliper mounting studs are also shimmed to achieve proper brake pad and caliper positioning with the rotor. Mount the caliper on these studs and check positioning. The positioning is determined by the number of shims between the caliper and bracket. You must have the same number of shims on each stud.

15-16. Brake pad installation is straightforward as shown, with pads positioned and pinned in place for extraordinary stability. Secure the pins, then the circular pin retaining clips. These BP-10 compound Smart Pads welcome extremes of braking and heat without breaking a sweat. Key to success is proper bedding and break-in when you take that first test drive.

17. The Wilwood six-piston Aerolite caliper is mounted and secured. Retaining nuts are torqued to 47 lb-ft. Double-check the caliper-to-rotor clearances.

18-19. Wilwood braided stainless steel brake hose and fittings are installed next. Teflon tape is used on the brake caliper fitting, which is tightened to the point when there is no brake hose binding or conflict. Wilwood provides all fittings and mounting hardware. What’s more, it looks factory installed.

20. Wilwood’s Aerolite 6R six-piston front disc brake delivers extraordinary braking performance coupled with striking looks you can see through wheel spokes. Key to success is methodical installation and break-in.

21-22. The S550’s 13-inch factory rear disc brakes, like the fronts, are the most brake the Mustang has ever had along with independent rear suspension. Wilwood believes you can go the factory disc brake one better with the Aerolite 4R/MC-4 14-inch rear disc brake package. Installation is straightforward. Wilwood provides easy-to-install, custom-fit parking brake cables.

23. Once the brake caliper is removed and parking brake cable disconnected, the rotor slides off. The stock 13-inch rotor weighs 17.1 pounds. Wilwood’s 14-inch rotor weighs 14.8 pounds. Less weight, more rotor.

24. As with the front rotors, the rotor and hat get Loctite 271 on bolt threads or safety wire and 155 lb-in of torque. Tighten the bolts crisscross.

25. Expect the same procedure with the rear Aerolite disc brakes. Calipers are shimmed to get them centered and clearanced once the bracket is installed. Temporarily install the bracket, rotor, and caliper. Check clearances.

26. Brake hydraulics can be handled the same way as in front. Wilwood provides braided stainless steel lines and hardware.

27. Minimum wheel-to-caliper clearance is 0.080 inch just like in front. The reason for the minimum clearance is thermal expansion when calipers get hot.

28. Rear brake hydraulics should look like this at the framerail and wheelhouse. The left side is shown here.

29-30. Wilwood provides you with a complete custom parking brake cable package, which replaces the stock parking brake cables. Brackets need to be transferred to the Wilwood cables. You are going to need a vise for this.

31. The completed Aerolite 4R/MC-4 disc brake package, which includes the parking brake on top. The MC-4 parking brake is a separate bolt-on unit actuated by the new Wilwood cables. When you bleed your new Wilwood disc brakes, always use a catch container and a solid hose between the bleeder and fluid in the container. You want seamless fluid flow from the bleeder to the container. Begin brake bleeding at the brake farthest from the master cylinder. Rears first. Front second. Keep the master cylinder full.

32-33. Wilwood binders on an S550 Mustang GT show nicely sporting new 20x9 10-spoke Niche Essen wheels front, 20x10 rear, on sticky Falken ultrahigh-performance tires ready for both road course and commute. Falkens hold the road in extreme driving conditions. Marry them to Wilwood 6R and 4R disc brakes fore and aft and you wind up with world-beating performance, making it challenging for others to follow closely.

Bleeding & Break-In

Wilwood recommends its Hi-Temp 570 grade brake fluid. If you are going to tax your brakes in competition, opt for Wilwood EXP 600 Plus. Silicone brake fluid is discouraged from racing and performance driving. If bleeding is unsuccessful you may need a larger master cylinder bore size. A firm pedal that slowly sinks to the floor indicates a leak in the system. A spongy pedal means air in the system.

In the interest of safety, make sure your brakes work before you leave the garage or driveway. Do you have a firm brake pedal? At a creep do they stop the car? At 15-20 mph do they stop the car when you slam them on? Do a visual inspection for leaks and other abnormalities.

When you are confident that brake function is normal and healthy, perform a low-speed road test. Do this in a safe location where you are not a threat to anyone else. You will want to accelerate to 65 mph and slowly build heat into the brake pads. Light braking decelerations down from 65 mph warms up the pads. You want a cycle of heating and cooling. Braking, then slow roll without brakes applied to a stop.

To complete the brake bedding cycle, accelerate to 55-65 mph with hard deceleration down to 25 mph. Do 8-10 of these heat cycles to 55-65 mph, then hard braking down to 25 mph. Brake pad bedding is complete. Inspect the pads and rotors after break-in. Rotors should show a uniformly burnished finish according to Wilwood Engineering. Any abnormalities in the rotor surfaces need to be checked and corrected. If you have any questions contact Wilwood’s tech staff.