Christopher Campbell Technical Editor
May 27, 2015
Photos By: Henry De Los Santos

It wasn’t long ago when the editors at our sister publication Motor Trend did some performance testing on the 2011 Mustang GT versus the 2011 BMW M3 on all fronts. Their rationale was that 2011 marked the first year that they considered the Mustang to have really come into its own enough in stock form to be a contender against the German. While we’ll reserve opinion on that, we do have to concede that one facet in particular had improved dramatically: braking.

In that 2011 test, both the Mustang and M3 stopped 60-0 in 104-105 feet, repeatedly. That’s extremely good by any standards. However, go back a few years and that braking performance drops off quickly. Go back from the fifth to the fourth generation and it drops off considerably. In peak new condition, a 1999 GT, like our project car, could do a best of 60-0 in 135 feet, but probably only once (twice at best) before fade started extending that distance.

That’s because the lowly two-piston stock calipers and small-diameter rotors were known for heating up, fading quickly, and even completely going away on track. We know, we’ve been there. We’ve boiled gallons of fluid and even spontaneously combusted a set of pads. The thermal capacity definitely leaves quite a bit to be desired. We’re going to change that forever as of right now.

When it comes to big brake swaps, Wilwood Engineering has taken the tough part out with its new Mustang-specific brake swap page at wilwood.com/Mustang. After you choose your year and spindle type, the page presents all front and rear brake package options available for your car. Of course, if you need something a little special, Wilwood can tailor a complete kit for your particular parts. It’s just that simple!

The kit is super-easy to bolt-on, doable in any garage with basic tools, but Wilwood Engineering’s own Tony Porto was kind enough to handle the install on our 1999 GT just to show us how quickly it can go together with a pro behind the wrench.

1. For maximum stopping power, our front kit features Wilwood's billet Forged Narrow Superlite 6R six-piston calipers teamed up with PolyMatrix pads and zinc-plated 14-inch directional, slotted, and internally vaned hat-style or hub-type rotors. Plus, the hat-type rotors are compatible with stock master cylinder output and ABS components. The kits include all brackets and mounting hardware needed to make it a bolt-on proposition.

2. For reference, here’s an exploded view of how the kit with two-piece rotor comes together on the stock spindle.

3. Here’s the stock caliper and rotor assembly common to all 1999-2004 GTs. Perfectly fine for daily driving, but falls of quickly for performance use due to poor thermal capacity.

4. To install the radial mount style caliper, we need to add a bracket to our spindle. In most cases two of the provided shims should space the caliper perfectly, so Wilwood recommends starting there. Note that we also removed the stock dust shield.

5. The Wilwood mount bolts to the spindle using the stock caliper hardware and provides studs that the new caliper will slide onto.

6. Our rotors are two-piece design, which makes for a much lighter overall package as well as easy upgrade and replacement. To assemble them, the provided Wilwood hardware is given a smear of red Loctite.

7. The bolts need to be torqued to spec in a star pattern, much like tightening a wheel, so make sure to have your torque wrench on hand. The bolts are also capable of being safety wired if your plans require it.

8. After securing the rotor to the hub with three lugs to make sure it is fully seated, we’re ready to fit the caliper. Two shims and this spacer slide onto the studs before install.

9. The only way to see whether our spacing is proper is to install the pads and note their distance from the rotor. We should have an equal distance from the pad face to the rotor face when the pads are fully seated. If not, shims will need to be added or subtracted from the radial mount to the spindle.

10. Our setup looked spot-on with the recommended two shims, so the center retaining bridge was installed. Note that this is the only part on the system that should be snugged tight. Too much torque could distort or bind the caliper.

11. While we were under there, we decided to swap out the flexible lines to Wilwood’s braided stainless stuff since ours were 16 years old. These are a quick bolt-on thanks to Wilwood’s application-specific lines.

12. The rear doesn’t need anywhere near as much brake as the front, but it could certainly do with a bit of an upgrade from the stocker. If nothing else, they’re ugly.

13. The caliper unbolts from this bracket on the rearend housing. With it out of the way, these thin sleeves slide into the bracket.

14. Inside the sleeves, new Wilwood hardware is slid in along with two shims. These bolts are smeared with red Loctite as well.

15. The rear radial mount bracket is torqued into place on the outer of the two threaded holes.

16. Just as with the front, the rotor is seated with three lugs to ensure it does not move while we check clearance. The studs will get two shims to space the caliper.

17. Our rear upgrade is a combination hydro-mechanical parking brake caliper, which uses hydraulic pressure from the master cylinder for stopping power and an internal mechanical lock within the caliper for a parking brake.

18. We also opted to upgrade the rear flexible line with a Wilwood braided stainless line. These are supplied with a new frame mount bracket that will meet up with the factory hard lines.

19. To utilize the parking brake on the new caliper, we need to upgrade the Mustang’s cables as well. On the caliper end, the preterminated ball slides into this bracket

20. Routing the new parking brake cable is a no-brainer since it makes use of the original loops to snake it through the chassis.

21. Here’s the only slightly tricky part. The two new parking brake cables are joined to the single one running up to the lever. Since it uses factory mounting brackets and balance bar, and the cables are the correct length, the main issue is just getting them mounted up there in the trans tunnel. Everything else is easy.

22. With much higher performance brakes, we wouldn’t run anything less than the best brake fluid. Wilwood’s own EXP 600 Plus is terrific stuff for street and track use and is surprisingly cheap considering its full race capability. All old fluid needs to be flushed, so Wilwood recommends bleeding the caliper farthest from the master cylinder first, and bleeding the outboard crew first, then the inboard.


Fresh rollers

Great brakes can only do their job with great traction. We ditched our Mustang’s thin stock package for these good-looking 18x9 and 18x10 AMR wheels from American Muscle paired with 275 and 295 series BFGoodrich g-Force T/A KDW tires. Not only will we get the most out of our new Wilwood brakes, but we also massively upped our project’s style points for a really reasonable investment.