Chrysler 300M Service Manual page 155

5 - 48 BRAKES - BASE BRAKE SYSTEM
PROPORTIONING VALVE (Continued)
(27) If no problem is found with the proportioning
valves, check the rear wheel brake shoe linings for
contamination or for replacement brake shoes not
PROPORTIONING VALVE APPLICATIONS AND PRESSURE SPECIFICATIONS
Sales Code Brake System Type
All All Disc/Disc
ROTOR
DIAGNOSIS AND TESTING - BRAKE ROTOR
Any servicing of the rotor requires extreme care to
maintain the rotor within service tolerances to
ensure proper brake action.
Excessive runout or wobble in a rotor can increase
pedal travel due to piston knock-back. This increases
guide pin sleeve wear due to the tendency of the cal-
iper to follow the rotor wobble.
When diagnosing a brake noise or pulsation, the
machined disc braking surface should be checked and
inspected.
BRAKING SURFACE INSPECTION
Light braking surface scoring and wear is accept-
able. If heavy scoring or warping is evident, the rotor
must be refaced or replaced. (Refer to 5 - BRAKES -
BASE/HYDRAULIC/MECHANICAL/ROTORS
STANDARD PROCEDURE)
Excessive wear and scoring of the rotor can cause
improper lining contact on the rotor's braking sur-
face. If the ridges on the rotor are not removed before
new brake shoes are installed, improper wear of the
shoes will result.
If a vehicle has not been driven for a period of
time, the rotor's braking surface will rust in the
areas not covered by the brake shoes at that time.
Once the vehicle is driven, noise and chatter from
the disc brakes can result when the brakes are
applied.
Some discoloration or wear of the rotor surface is
normal and does not require resurfacing when lin-
meeting OEM brake lining material specifications.
These conditions can also cause premature rear
wheel skid.
Split Point Slope
400 psi 0.34 Bar Code Label
ings are replaced. If cracks or burned spots are evi-
dent, the rotor must be replaced.
ROTOR MINIMUM THICKNESS
Measure rotor thickness at the center of the brake
shoe contact surface. Replace the rotor if it is worn
below minimum thickness or if machining the rotor
will cause its thickness to fall below specifications.
CAUTION: Do not machine the rotor if it will cause
the rotor to fall below minimum thickness.
Minimum thickness specifications are cast on the
rotor's unmachined surface (Fig. 84). Limits can also
be found in the table at the end of this brake rotor
information.
-
1 - ROTOR MINIMUM THICKNESS MARKING
2 - ROTOR
Identification Inlet Pressure
1000 psi
Fig. 84 Minimum Thickness Markings (Typical)
LH
Outlet Pressure
525-625 psi