The majority of models have an inspection slot on the top of the caliper to examine the pad thickness after the front wheels have been removed, and in case the thickness is judged to be marginal, the pads must be removed to make a thorough check, and models without an inspection slot require pad removal to measure caliper thickness. The front disc brake pads have wear indicators which touch the surface of a rotor when the brake has been worn to a minimum thickness, which causes a squealing sound. With rear-wheel drive GLC models, one should work on removing one side at a time with both sides changing pads. Start by loosening the lugs on wheels, lifting the car and taking off the front wheels. Take off the locking clip and stopper plate that holds the caliper in place and then remove the caliper and hold on to it using wire. Take out the anti-rattle spring and slide out the pads and take note of their positions. To fit the new pads, take approximately one third of the brake fluid used in the master cylinder reservoir to push back out the displaced fluid. This should be done using a C-clamp, then new pads, shims, and anti-rattle spring should be installed and the caliper should be affixed with the stopper plate and locking clip. Do the same to the other side, install the wheels, lower the vehicle, and fill the master cylinder with new brake fluid then pump several times the brake pedal. In the case of front-wheel drive GLC models, that would consist of lifting up the vehicle, unclipping the brake hose, unclipping the spring clip and lifting the caliper upward without cutting the brake line. Installation After the pads are removed, repeat the same steps to ensure that there is a correct fluid management and transfer of the components. The 626 models manufactured in the 1979-82 have a floating caliper design, which needs the same procedure in the replacement of the pad, including fluid handling and re-assembling. The 323, MX-6 and 1983-89 model 626 models have a similar procedure, in which it is strongly advised not to disconnect the brake line. The 929 model involves lifting the front section, eliminating the lower lock pin bolt and fluid levels and then replacing pads. The models include the 1979-85 RX-7 with locking clips and stopper plates that need to be removed and the 1986-89 RX-7 with 14 inch wheels that need to push the piston of the caliper back in and clamp it. In models that do not have 14 inch wheels, the removal of the pads requires no caliper removal which makes the process of changing pads and attaching the components much easier.