Scion 43512-52120 Front Disc

Chock the front wheels, then jack up the rear of the vehicle and support it on axle stands before removing the rear roadwheels. Detach the rear brake caliper from the disc without disconnecting the flexible hose, and support the caliper on an axle stand or suspend it with wire to avoid straining the hose. Temporarily refit two wheel nuts to diagonally-opposite studs with the flat sides against the disc and tighten them progressively to hold the disc firmly. Scrape any corrosion from the disc, rotate it, and examine for deep scoring, grooving, or cracks, measuring the thickness in several places with a micrometer; the minimum thickness is stamped on the disc hub. Light wear and scoring are normal, but excessive wear requires removal for regrinding or replacement, ensuring the minimum thickness is maintained, and cracked discs must be renewed. Check the disc run-out 10 mm from the outer edge using a dial gauge or flat metal block and feeler gauges, ensuring it does not exceed the specified limit by fixing the measuring equipment and rotating the disc to note measurement variations. If the run-out is excessive, check for variations in disc thickness by marking the disc at eight positions 45° apart and measuring the thickness 15 mm in from the outer edge; if the variation exceeds the specified amount, the disc should be renewed. The hub face run-out can also be checked by removing the disc, fixing the measuring equipment, and rotating the hub to ensure the run-out does not exceed the specified amount; excessive run-out should be corrected by renewing the hub bearings before rechecking the disc run-out. With the wheel and caliper removed, take off the temporarily refitted wheel nuts, mark the disc in relation to the hub if it is to be refitted, and remove the washer/retaining clip(s) if fitted, then withdraw the disc over the wheel studs. Ensure the disc and hub mating surfaces are clean, locate the disc on the wheel studs, and align the previously made marks if the original disc is being refitted. Refit the washer/retaining clip(s) if applicable, then reattach the brake caliper and carrier bracket, followed by the wheel. Lower the car to the ground and tighten the wheel nuts to their specified torque, then test the brakes carefully before returning the car to normal service.

Apply the handbrake, then jack up the front and rear of the car. Support it securely on axle stands. Remove the front roadwheels. The brake pad thickness, and the condition of the disc, can be assessed roughly with just the wheels removed. The thickness of the brake pads can be seen through the caliper window. For a comprehensive check, the brake pads should be removed and cleaned. The operation of the caliper can then also be checked, and the condition of the brake disc itself can be fully examined on both sides. On completion, refit the roadwheels and lower the car to the ground.