Wheel studs or lugs are the bolts that clamp the wheel to the rotor with the clamp pressure from the lug nuts. There may be as few as four on a small utility or boat trailer and as many as twelve or more on large industrial or tractor-trailer rigs. Studs may be easily replaced without any specialty tools, though a small hydraulic or arbor press can make the job easier.
Break the torque on the lug nuts with the vehicle on the ground. Set the parking brake and jack the vehicle up to lift the wheel off the ground, then rest the vehicle on jack stands. Finish removing the lug nuts and then remove the wheel. Do not breathe any of the brake dust that might be released as it contains asbestos.
Remove the brake caliper. Caliper construction varies by make and model, but generally the caliper is held in place by two or three bolts or pins. Remove the fasteners and try to cock the caliper on the rotor to compress the brake cylinder. Clamp pressure may be needed to achieve this, requiring a screw clamp or careful jacking with a couple of flat screwdrivers. The caliper should come free of the rotor now. Hang the caliper from some convenient point with the shock cord. Never support the weight of the caliper with the brake line as it could break the metal fitting and ruin the line.
Straighten the cotter pin on the spindle using needle-nose pliers and then remove the pin from the castle nut. Remove the castle nut and the bearing nut, and then slide the rotor off the spindle. If the rotor is frozen in place, give it a firm bump with a hammer or rubber mallet. Take care not to ding the surface of the rotor.
Apply some penetrating oil to the base of each stud and allow some time for the oil to work. Place the rotor on a sturdy surface and drive the studs out with a heavy hammer. A small press may be used if available for this step. Support the rotor on the press bench, and drive the studs out from the front of the rotor pushing the studs out the back.
Lightly grease the new wheel studs with anti-seize compound. Drive the new studs into the rotor with a hammer or press. Be certain to seat the new studs fully against the back of the rotor.
Remove the old bearing seal at the back of the rotor. Remove and repack both bearings with fresh grease. Install a new wheel bearing seal onto the back of the rotor by driving it in lightly with a hammer. Be careful to drive it in evenly and to not distort the seal.
Slide the rotor back onto the spindle and install the outer bearing. Refer to the vehicle manufacturer's instructions and specifications for exact wheel bearing nut torquing procedure. Slide the castle nut over the wheel nut and replace the cotter pin.
Reinstall the caliper and the wheel by reversing the removal procedure.
