Pop the wheel, pull the two 13mm slide bolts, lift the caliper out of the bracket, swap pads, compress the piston with a C-clamp, then unbolt the bracket from the knuckle, slide the rotor off the hub, and reverse — about 90 minutes for both fronts on a YJ.
Front brakes on a YJ are stopped-clock straightforward: single-piston floating caliper, vented rotor, two pad shims, two slide pins. The 1987–1989 trucks use a smaller rotor and caliper than the 1990+ trucks, which got the heavier brake setup that ran through every TJ and most XJs. Pads and rotors are wear items — replace pads when there's 3mm of friction material left, replace rotors any time you replace pads if the rotor is below minimum thickness (stamped on the hub face) or has hard scoring you can feel with a fingernail.
Treat this job with respect — brakes are not where you cut corners or hurry. Use jack stands on the frame rails, not on the axle (the axle moves up when you remove the wheel and weight). Pump the brake pedal once after reassembly and before you move the truck to push the pads against the rotor; if you skip this, your first stop has no brakes. Then drive 10–15 mph in an empty lot and do a few firm stops to bed the new pads — this transfers a thin layer of friction material onto the rotor face, which is what actually does the stopping.
Compressing the piston pushes brake fluid backward through the line and up into the master cylinder reservoir. Open the reservoir cap and remove a few ounces of fluid before you compress, or it'll overflow when you push the piston in. A C-clamp with the old pad as a pad-saver works fine; a proper caliper compressor tool is faster but $25 you don't need to spend. While the rotor is off, take 60 seconds with a wire brush to clean the hub face — rust between the hub and the rotor is what causes that pulsating brake pedal six months later.
Brand math: PowerStop's Z16 kit at around $120 gets you pads and rotors that exceed factory performance and run cooler than the OEM Mopar units. Bosch QuietCast ceramic pads on Raybestos Professional rotors is the spend-no-more-than-needed option at about $115. Akebono ceramic pads are the quietest available but cost more — fair tradeoff if you daily-drive the YJ. Avoid the no-name $30 rotor kits on eBay; they warp inside a year and the pad material doesn't bed properly.
| Part | Vendor | Est. price |
|---|---|---|
| PowerStop Z16 Autospecialty front kit (pads + rotors) | PowerStop | ~$120 |
| Bosch QuietCast ceramic pads (front) | Bosch | ~$38 |
| Raybestos Professional Grade rotors (pair) | Raybestos | ~$75 |
| Brake cleaner aerosol | CRC or Permatex | ~$5 |
| Anti-seize for caliper slide pins | Permatex | ~$8 |
Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.