Brake Rotor/Disc: Testing and Inspection

Measuring brake disc lateral runout (front/rear)

Special tools:
999 9696 MAGNETIC BASE 999 9696 Magnetic Base
999 9684 DIAL INDICATOR 0-10 MM 999 9684 Dial Indicator 0-10 mm

Preparations
Remove the hub cap and wheel.
Front: Remove the brake caliper from the holder and remove the brake lining.
Rear: Remove the brake hose from the support.
Remove the entire brake caliper from the rear axle; see step Replacement of rear brake disc Brake Disc Rear, Replacing.

Fastening the brake disc to the hub
Fit the wheel nuts with the flat side inward and tighten to 110 Nm.

Measuring brake disc lateral runout




Assemble the dial indicator ( 999 9696 MAGNETIC BASE 999 9696 Magnetic Base , 999 9684 DIAL INDICATOR 0-10 MM 999 9684 Dial Indicator 0-10 mm ) and position it against the brake disc.
Slowly rotate the hub using a socket wrench. Maximum permissible lateral runout on the outside of the hub rear/front is 0.07 mm.
If the maximum lateral runout is exceeded, the disc must be replaced or turned down (if tools are available for such).

Note! This lateral runout can also be caused by the hub's lateral runout. Check hub lateral runout as necessary. See Measuring lateral runout in hub (front/rear) Testing and Inspection.

Work element during replacement as described in Front brake disc replacement Brake Disc Front, Replacing (front) or Replacement of rear brake disc Brake Disc Rear, Replacing (rear).

Finishing work




Refit the brake lining and brake caliper.
See step Front brake disc replacement Brake Disc Front, Replacing (front) or Replacement of rear brake disc Brake Disc Rear, Replacing (rear).
Remount the wheel, see step Replacing front brake pads Brake Pads Front, Replacing.