Chevrolet BEAUVILLE SPORTVAN G10 SERIES Service Manual Download Page 122

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BRAKES 5-21

Light Scoring

Light scoring o f the disc surfaces n o t exceeding .015 inch in

d e p th , w hich m ay result from norm al use, is n o t detrim ental
to brake operatio n .

Checking Lateral Runout

T ighten the wheel bearing adjusting n u t u n til all o f the play

is out o f the bearing. I t should be ju st loose enough to allow

the wheel to tu rn . F asten a dial indicator to some p o rtio n o f
the suspension so th a t the p o in t o f the stylus co n tac ts the

ro to r face approxim ately one inch from the ro to r edge. Set the

dial at zero an d m ove the ro to r one com plete ro ta tio n ,

checking the in d ic ato r as the ro to r moves. A fter checking the
ru n o u t, readjust th e w heel bearing (See S ection 3).

Checking Parallelism

To check for parallelism , m easure th e thickness o f the ro to r

at four or m ore p o ints aro u n d th e circum ference o f th e ro to r.

All m easurem ents m ust be m ade a t th e same distance in from

the edge o f the ro to r.

MASTER C Y L IN D E R (Fig. 40)

C A U T IO N :

Always use denatured alcohol or brake

flu id to clean any master cylinder parts. Never use

mineral-base cleaning solvents such as gasoline, kero

sene, carbon-tetrachloride, acetone, paint thinner or

units of like nature as these solvents deteriorate

rubber parts, causing them to become soft and

swollen in an extrem ely short tim e.

Removal

1. Wipe m aster cylinder an d lines clean w ith a clean cloth.

Place dry cloths below m aster cylinder area to absorb any

fluid spillage.

2. D isconnect h y d rau lic lines a t m aster cylinder. Cover line

Fig. 4 0 —Master C ylinder - Typical

ends w ith clean lint-free m aterial to prevent foreign
m a tte r from en tering the system .

3. D isconnect the push rod from the brake pedal.
4. U nbolt and rem ove the m aster cylinder from the dash

panel or pow er brake booster.

Disassembly (Fig. 41)

1. Rem ove the small secondary p isto n stop screw from the

b o tto m o f the fro n t fluid reservoir o f the m aster
cylinder.

2. Place th e m aster cylinder in the vise so th a t th e lock ring

can be rem oved fro m th e small groove in the I.D . o f the
bore. Rem ove th e lock ring and prim ary piston assembly.

Remove  th e  secondary  p iston,  secondary  p isto n   spring
and  retainer  by  blow ing  air  th ro u g h   the  stop  screw hole.
If  air  is  n o t  available,  a  piece  o f  wire  m ay  be  used.  Bend

approxim ately 1 /4 ” o f one end o f the wire in to a right
angle. H ook this end u nder th e edge o f th e secondary

piston and pull th e secondary p isto n from the bore.

C A U T IO N :

Do n ot clamp vise to o tigh tly as d am 

age to the master cylinder could result.

N O T E : The brass tube-fitting insert should N O T

be removed unless visual inspection indicates the

insert is damaged.

3. To replace a defective insert th e following procedure

should be practiced:

Place  th e  m aster cylinder in  a  vise, so  th a t  th e  o utlet
holes  are  u p .  Enlarge  the  o u tle t  holes  in  the  tube
seats  using  a  1 3 /6 4 ”  drill.  Tap  a  l / 4 ” -20  thread  in
these  holes.  Place  a  heavy  w asher  over  the  o u tle t  on
the  m aster  cylinder  and  th rea d   a  1/4”   -  20  x  3 /4 ”
hex  head  b o lt  in to   the  tu b e  seat.  Tighten  the  bolt
u ntil  th e  tube  seat is unseated.

A m ore preferable w ay to rem ove a defective insert
involves use o f a self-tapping screw and a claw

C H E V Y V A N S H O P M A N U A L