How To Install Four-Wheel Disc Brakes On A Fox 5.0

Once the splash shields are mounted, the new axleshafts can be inserted into the housing. Carefully slide them in, avoiding contact with the axle seal and bearing; engage the splined ends with the differential and gently push the axle in until it bottoms out. Slide the C-clip retainers on the ends of the axleshafts, then pull each shaft out until the clip seats. The crosspin is then reinstalled and the differential cover sealed.

Before mounting the calipers, the antimoan caliper-brace brackets must be mounted. These are intended to quell the noise that can be generated by the rear brakes during slow, creeping braking, such as in traffic. These are also marked with left and right designations. The bracket is lined up with the caliper mounting flange and fastened with a U-bolt around the axle tube; the U-bolt should be left loose at this point.

The caliper can be mounted after the new rotor is slipped over the axle flange. Ken opted to install the caliper slider bracket to the axle bracket first, leaving the caliper off. Once the caliper bracket is torqued to 70-95 lb-ft, the U-bolt from the previous step can be tightened to 40-45 lb-ft.

The new rear pads are positioned in the slider bracket, using the small metal shim tabs that come with them. The new caliper is slipped over the pads and into position on the bracket.

All the plumbing for the rear brakes will be replaced, starting with the flex hose from the chassis to the axle housing; it's all included in the kit. There are two additional flex hoses with the new rear discs, one at each caliper. Brackets for each have to be mounted to the shock mounting brackets on the axle housing

The kit includes two sets of parking-brake cables: one for '87-'92 and one for '93 models. Ken took the '93 cables and started by connecting the ends to the calipers with the included clips. The cables are then routed to the transmission tunnel the same way as the originals; they're mounted using the factory clamps. A new intermediate cable to connect the lever with the balance bar is included.

A new power brake booster and master cylinder are included in the kit. The new cylinder uses a larger internal-bore diameter to move more fluid for the increased volume of the new twin-piston calipers up front and single-pistons out back in place of wheel cylinders. The bigger booster will generate more assist to move all those pistons quickly. Clearance to the strut tower is minimal. In fact, the instructions advise that '90-and-earlier Mustangs may require that the tower be "relieved" with some hammer blows to allow installation.

All '87-'93 5.0 Mustangs use a master cylinder that has three lines rather than the usual two. The third line comes out of the bottom of the cylinder and goes to the left-front brake, bypassing the combination valve, which has a plug where the left-front brake line would normally connect. The new master cylinder resembles the original but has a larger-diameter bore and two outlets. The left-front brake line will have to be cut, rebent, and reflared with a different fitting (included) to connect to the new junction.

The original combination valve is replaced with a similar piece, though the new unit will have to be modified for use with the included adjustable proportioning valve. The plug on the end of the valve is removed and the spring and plunger are pulled out. The O-ring is transferred to the new plug, which is installed; it's critical to use the new plug because the old one will blow out without the plunger.

The new adjustable proportioning valve fits into the rear brake line in the engine bay along the firewall near the passenger-side hood hinge. There is a factory union fitting in this location that will allow the proportioning valve to be installed without any cutting or flaring. Simply remove the union and install the lines to the new valve, making sure the one coming from the driver side attaches to the port marked "in."

We wanted to use the Cobra R wheels on our car, but their 9-inch width is tight. Ford Racing offered special versions for Fox Mustangs with this brake kit or similar Ford rear discs, which widen the rear track. The front wheels are standard '95 Cobra R (R58) with 5.98-inch backspacing while the special rears (M179) have 6.42 inches. Unfortunately, they have since been discontinued. Using a 17x8-inch SN-95 ('94-'04) factory-spec wheel with 5.72-inch backspacing would allow the same wheels on all four corners.