Chrysler RAM TRUCK 2500 1994 Service Manual page 213

5 - 54 DISC BRAKES
•
Fig. 29 Front Brake Hose Attachment
CONTROL
FRONT HOSE
A N D TUBE
ASSEMBLY J9405-51
Fig. 30 Front Brake Hose Routing (4-Wheel Drive)
DISC BRAKE ROTOR INSPECTION AND SERVICE
Rotor Condition
Rotor condition and tolerances can be checked with
the rotor mounted i n a brake lathe, or on the axle. I f
the rotor is checked on the axle, be sure wheel bear­
ing end play is reduced to zero before measuring lat­
eral runout.
The rotor braking surfaces should not be machined
unless actually necessary. Light surface rust and
scale can be removed i n a lathe equipped with dual
sanding discs.
Worn, or scored rotor surfaces can be restored by
machining i n a disc brake lathe but only i f surface
scoring and wear are light.
The rotor should be replaced if:
• severely scored
• tapered
• has hard spots
• cracked
• warped
• too thin
• machining would cause rotor thickness to fall be­
low minimum thickness requirements
CHECKING ROTOR MINIMUM THICKNESS
Measure rotor thickness at the center of the brake-
shoe contact surface. Replace the rotor i f i t is worn
below minimum thickness, or i f refinishing would re­
duce thickness below the allowable minimum. Rotor
minimum thickness is usually specified on the rotor
hub, or on the outer edge of the rotor ventilated sur­
face.
ROTOR THICKNESS VARIATION
Variations i n rotor thickness will cause pedal pul­
sation, noise and shudder.
Measure rotor thickness at 6 to 12 points around
the rotor face (Fig. 31). Position the micrometer ap­
proximately 25.4 mm (1 in.) from the rotor outer cir­
cumference for each measurement.
Thickness should not vary by more than 0.025 mm
(0.001 in.) from point-to-point on the rotor. Refinish
or replace the rotor i f necessary.
Fig. 31 Measuring Rotor Thickness Variation
Checking Rotor Lateral Runout
Check rotor lateral runout i f pedal pulsation or an
occasional low pedal condition was experienced. Ex­
cessive lateral runout will cause pedal pulsation and
rapid, uneven wear of the brakeshoes. Measure
runout with a dial indicator (Fig. 32).
Check runout with Dial Indicator C-3339 (Fig. 32).
Position the indicator plunger at least 25.4 mm (1
in.) inward from the outer edge of the rotor. On