The GMC Envoy uses a caliper and rotor design to maximize clamping force on the rotors and improve braking. Hydraulic fluid runs through steel tubing, called "brake line" and creates the pressure needed in the brake system to stop the vehicle. The calipers and brake pads are what physically do the stopping by creating friction against the brake rotor. The rotor is a disc connected to the drive wheels. Over time, the pad material will wear down as the lining, or brake pad, is worn away by friction. When the pads are 1/8 inch, you need to change the brakes.
Loosen the wheel lug nuts by turning them counterclockwise 1/4 turn.
Raise the Envoy on jack stands. Use the factory jack point in the front the vehicle. The jack points are located behind the radiator (front) and behind the trunk, near the bumper (rear). To change the front brakes, you'll need to jack up on the front of the vehicle. To change the rear, you'll need to use the rear jack point.
Place a jack stand under each of the four pinch welds located in the front and rear of the Envoy (if you are changing all of the brakes at once).
Finish loosening and remove the wheel lug nuts, and pull the wheel off the wheel hub.
Loosen the top and bottom caliper mounting bolts and remove the brake caliper. Then, secure the caliper to the coil springs on the suspension with zip-ties.
Pop the old brake pads out of the caliper using a rubber mallet. You may be able to remove them by hand, but sometimes they get stuck in the caliper. Rest the face of one of the old brake pads against the piston of the caliper and slide a c-clamp over the brake pad and caliper assembly. When you tighten the clamp, it will force the pad against the piston and force the piston back into the caliper. You need to force the piston back into the caliper so that the new, thicker, brake pads will fit.
Insert the new pads with the curved side of the brake pad facing inwards toward the caliper. Align the tabs on the top and bottom of the new pads with the retaining clips on the caliper and press the tabs into the retaining clips.
Reassemble the brake caliper. Installation/assembly is the reverse of removal.
Spray the entire brake assembly down with brake parts cleaner and a clean rag.
Install the wheel and tighten the lug nuts. Lower the Envoy to the ground and torque the lug nuts to 100 lbs-ft. with a torque wrench. Set the dial on the torque wrench to 100 lbs-ft. and turn the lug nuts clockwise in a criss cross pattern with the torque wrench until the wrench clicks.
Pump the brakes to restore brake pressure until the pedal is firm.
