Dodge D150 1990 Service Manual page 248

Rear wheel drive ram truck

Table of Contents

ROTOR INSPECTION AND SERVICE

Rotor condition and tolerances can be checked w i t h

t h e rotor mounted o n t h e axle. However, wheel bear-

i n g end play should be reduced t o zero before check-

i n g l a t e r a l r u n o u t .

The rotor b r a k i n g surfaces should not be machined

unless actually necessary. L i g h t surface r u s t a n d

scale can be removed i n a lathe equipped w i t h d u a l

sanding discs. T h e rotor surfaces can be restored b y

m a c h i n i n g i n a disc brake lathe i f surface scoring

and wear are l i g h t . T h e rotor should be replaced i f

severely scored, tapered, has h a r d spots, i s cracked,

too t h i n , or i f m a c h i n i n g w o u l d cause rotor thickness

to f a l l below m i n i m u m thickness requirements.

Check rotor l a t e r a l r u n o u t and thickness v a r i a t i o n

i f pedal p u l s a t i o n or a n occaisional low pedal condi-

t i o n was experienced. Measure r u n o u t w i t h a d i a l i n -

dicator. Measure thickness w i t h a micrometer a t a

m i n i m u m of four points around the b r a k i n g surfaces.

The rotor measurement points are shown i n F i g u r e

Measure rotor thickness a t t h e center o f the brake-

shoe contact surface. Replace t h e rotor i f i t is w o r n

below m i n i m u m thickness, or i f r e f i n i s h i n g w o u l d re-

duce thickness below t h e allowable m i n i m u m . Rotor

m i n i m u m thickness i s u s u a l l y specified o n t h e rotor

V a r i a t i o n s i n rotor thickness w i l l cause pedal p u l -

sation, noise a n d shudder.

Measure rotor thickness a t 6 to 12 points a r o u n d

t h e rotor face ( F i g . 17). Position t h e micrometer ap-

p r o x i m a t e l y 25.4 m m (one inch) f r o m t h e rotor outer

circumference for each measurement (Figs. 16 a n d

Thickness should n o t v a r y by more t h a n .025 m m

(.001 inch) f r o m point-to-point on t h e rotor. Refinish

or replace t h e r o t o r i f necessary.

Fig. 16 Rotor Measurement Points