The PowerStop S4378 is a pair of front calipers, with brackets, for the 1994-1998 Ford Mustang. Each unit is a floating caliper with a single piston, and the manufacturer finishes it in an electrostatic high-temperature red powder coat. The manufacturer says the calipers and brackets are remanufactured in its Chicago facility, and that every caliper is pressure tested for piston operation and leaks. Rebuilt replacements from unknown sources rarely document that testing. Each caliper is assembled with new seals, guide pins, EPDM dust boots, bleeder screws, and stainless pad abutment clips, plus high-temperature silicone lube on the pins. Owners who want the look of red calipers behind aftermarket wheels, with corrosion resistance and rebuilt internals, will find this a practical stock-platform refresh. It is not a big-brake kit. Search terms this part matches include 94-98 Mustang GT front red calipers, 1994-1998 Mustang V6 brake calipers, and PowerStop S4378 front caliper pair.
Fitment is the step that needs the most care. The manufacturer's application lists the 1994-1998 Mustang GT and V6, but other channels also show base, GTS, Thunderbird, and Cougar applications, so confirm the exact vehicle with the manufacturer before ordering. Owners on user forums note that 94-98 Cobra calipers use smaller pistons than the GT and V6 units, so do not assume the two are interchangeable. For installation, owners on user forums describe the front swap as a straightforward bolt-on, provided you replace the pads and rotors, bleed the system, and avoid mixing up the left and right front brake lines, which are not interchangeable. Check the banjo bolts too, since some new calipers ship without them. Plan to compress the piston with a C-clamp or compressor, and then bed the new pads according to the manufacturer's break-in procedure.
Yes. The manufacturer's break-in procedure for drilled and slotted rotors calls for five moderate to aggressive stops from 40 mph to 10 mph without coming to a complete stop, followed by five stops from 35 mph to 5 mph, then a cool-down drive at moderate speed.
Not necessarily. Owners on user forums report that 94-98 Cobra front calipers use a different piston size than the GT and V6 units, so confirm the application with the manufacturer before assuming a match.
This is a bolt-on front brake job that suits a home mechanic with basic tools, a jack and stands, a torque wrench, and a C-clamp or piston compressor. The manufacturer's install guidance directs you to the vehicle's service manual for complete instructions. Compress the piston with a used pad over its face to protect the surface, and inspect the banjo bolts and copper washers before reassembly. Left and right front lines are not interchangeable, so match each line to its side. Bleed the system after the caliper and line work, and keep the reservoir at the max line without overfilling. Owners on user forums say the swap goes smoothly when the rest of the front end is in good shape. Finish with the manufacturer's break-in procedure before driving normally.
