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TRUCK SERVICE MANUAL
TM 5-4210-230-14&P-1
PROBLEM
POSSIBLE CAUSE
REMEDY
Spongy Pedal (springy sensation
to pedal upon application)
Warped brake shoes.
Replace shoes.
Shoes not centered in drum causing
partial lining-to-drum contact.
Adjust brake shoe anchors.
Brake drums tapered, out-of-round or
worn thin.
Refinish if practical or replace.
Air in system.
Bleed and refill system with approved
hydraulic fluid.
Hoses soft or weak (expanding under
pressure).
Replace hoses.
Faulty residual check valve(s) in master
cylinder.
Replace valve(s).
Wheel cylinder cups soft or swollen.
Flush hydraulic system with alcohol to
remove contaminated fluid and replace all
cups and seals.
Hard
Pedal
(excessive
pedal
pressure required to stop vehicle)
Shoes worn, distorted or damaged.
Replace brake shoes.
Inadequate lining to drum clearance.
Properly adjust brake shoes.
Linings worn, glazed, soiled (brake fluid
or grease) or of poor quality.
Replace linings.
Brake lines, hoses or connections kinked,
collapsed, dented or clogged.
Repair or replace.
Master cylinder cups swollen.
Flush hydraulic system with alcohol to
remove contaminated fluid and replace all
cups and seals.
Master cylinder bore rough or corroded.
Repair or replace master cylinder.
Brake shoe anchors out of adjustment.
Adjust anchors.
Brake shoe ledges rusted or grooved.
Clean and smooth ledges and lubricate.
Wheel cylinder cups swollen.
Flush hydraulic system with alcohol to
remove contaminated fluid and replace all
cups and seals.
Wheel cylinder bore rough or corroded.
Repair or replace wheel cylinders.
Power cylinder check valve defective or
sticking
Replace.
Vacuum lines to power cylinder loose,
broken or collapsed.
Tighten or replace.
Low vacuum supply to power cylinder.
Check for restricted, kinked or leaking line;
also engine vacuum.
Control valve, power cylinder, piston or
diaphragm defective.
Replace defective part or power cylinder.
CTS-2055S Chapter IV Page 3
PRINTED IN UNITED STATES OF AMERICA
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