Section 7: Rotor; Inspection - Meritor MM-2075 Maintenance Manual

7 Rotor
Rotor
Hazard Alert Messages
Read and observe all hazard alert messages in this publication.
DANGER
Park the vehicle on a level surface. Block the wheels to prevent
the vehicle from moving. Support the vehicle with safety stands.
NEVER work under a vehicle supported only by jacks. Jacks can
slip and fall over. Failure to use a jack stand can result in serious
personal injury and damage to components.
WARNING
To prevent eye injury, always wear eye protection when performing
vehicle maintenance or service.

Inspection

1. Wear safe eye protection. Park the vehicle on a level surface.
Block the wheels to prevent the vehicle from moving.
2. Use a jack to raise the vehicle so that the wheels to be
serviced are off the ground. Support the vehicle with safety
stands.
3. With the pads removed, rotate the wheel and inspect the hub
and rotor assembly for damage.
4. Inspect both sides of the rotor for cracks and heat checks.
Replace the hub, rotor or entire assembly, if necessary.
5. Check the hub and rotor assembly for damaged, loose or
missing fasteners. For the correct torque, refer to Section 11
Specifications on page 26.
Cracks
WARNING
Always replace a cracked rotor to avoid serious personal injury
and damage to components.
When the crack extends through a section of the rotor, replace the
rotor. Figure 7.1.
MM-2075 / Revised 09-23
Page 16
Figure 7.1
Heat Checking
Heat checks are short, thin, sometimes numerous, radial
interruptions of the rotor braking surfaces. They are the result of
disc brake operation. They are caused by the heating and cooling
that occurs as the brakes are applied time after time. Heat checks
will frequently wear away and reform, or they may become braking
surface cracks, depending on such factors as the lining and rotor
wear rate, brake balance, and how hard the brakes are used. There
are two kinds of heat checking: light and heavy. Figure 7.2.
Figure 7.2
Light Heat Checking
Cracks on the surface of the rotor that result from light heat
checking are small and fine and do not require rotor replacement.
Figure 7.2 and Figure 7.3.
Copyright Meritor, Inc., 2023
4001599a
4001600a
(16579)
Printed in USA