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P A R T 2-1-GENERAL BRAKE SERVICE
2-7
the hydraulic system, flush the entire
system with clean denatured alcohol.
MASTER CYLINDER
1. Clean all master cylinder parts
in clean denatured alcohol, and in-
spect the parts for wear or damage,
replacing them as required. W h e n a
master cylinder repair kit is used, in-
stall all of the parts supplied in the
kit.
Check the ports and vents in the
master cylinder to m a k e sure that all
are open and free of foreign matter.
2. If the spring valve (riveted to
the front end of the piston) is loose,
or has moved so that the piston ports
are open, replace the piston.
3. Inspect the cylinder walls for
scores or rust, and recondition them
if necessary. H o n e the cylinder walls
no more than necessary (0.003-inch
m a x i m u m ) , either to remove scores
and rust, or to obtain a smooth wall
surface. R e m o v e any burrs or loose
metal that m a y have resulted from
the honing operation, and clean the
cylinder with clean denatured alco-
hol.
BRAKE DRUMS AND LININGS
1. After removing one front wheel
and drum from the truck, inspect the
d r u m and brake shoe linings for
wear or damage that would affect
brake operation. D o not let oil or
grease touch the drum or linings.
2. A brake shoe should be relined
when the lining face is worn to with-
in % 2 inch of any rivet head, or
when the lining has been soaked
with oil or grease. If a worn lining
is not replaced, the brake drum m a y
become severely damaged. Always
replace the primary and secondary
brake shoe lining assemblies on both
front or both rear brake assemblies
at the same time.
Before relining a brake shoe, in-
spect the shoe for distortion, cracks,
or looseness between the rim and
web. If one of these conditions ex-
ists, replace the shoe. D o not attempt
to repair a damaged brake shoe.
3. If the drum and linings are in
good condition, install the wheel and
drum. T h e condition of the drums
and linings of the other three wheels
will usually be about the same as
that found at the wheel that was
removed.
4. A d d enough heavy-duty brake
fluid to the master cylinder reservoir
to bring the level to within
3
/a inch
of the top of the filler neck.
5. O n an F-100, F-250, or P-350
truck, jack up the rear wheels and
check the parking brake cables to
m a k e sure that the cables have not
been adjusted so tightly as to m o v e
the rear brake shoes off their anchor
pin seat. O n all truck series, be sure
that the parking brake handle is fully
released before making any brake
adjustments.
6. Check the front brake anchor
pin nut with a wrench (on brake as-
semblies with an adjustable anchor
pin). If the bolt is loose, torque i t to
80-100 ft-lbs.
BRAKE BOOSTER
1. After disassembly, immerse all
metal parts in a suitable solvent. Use
only alcohol on rubber parts or parts
containing rubber. After the parts
have been thoroughly cleaned and
rinsed in cleaning solvent, the metal
parts which come in contact with
hydraulic brake fluid should be re-
washed in clean alcohol before as-
sembly. Use an air hose to blow dirt
and cleaning fluid from the recesses
and internal passages. W h e n over-
hauling a power booster, use all
parts furnished in the repair kit. Dis-
card all old rubber parts.
2. Inspect all other parts for dam-
age or excessive wear. Replace dam-
aged or excessively worn parts. If
the inside of the booster body is
rusted or corroded, polish i t with
steel wool or fine emery cloth. Re-
place the body shell when scored. In-
spect the master cylinder bore for
signs of scoring, rust, pitting or
etching. A n y of these conditions will
require replacement of the cylinder.
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