Diagnosis Chart - Cadillac 1937 LaSalle VVI Information

64
B R A K E S
Diagnosis Chart
Effect
Brake Pedal Goes A l l
Way Down to Toe
Board.
• A
Cause
Normal wear on linings.
Brakes Drag at AH
Wheels
Brake Drags at One
Wheel.
Leaks in brake system.
Air in brake system.
N o fluid in supply tank.
Mineral oil in brake system.
Port hole in master cylinder closed.
Remedy
Weak or broken brake shoe return spring
Brake shoes set too close to drum.
Cylinder cups distorted.
As the brake linings wear, it becomes necessary to set the
shoes closer to the brake drums. When adjusting the'
brakes the drums should be cool and the shoes should.be
set as close to the drums as possible without dragging.
The shoe anchor pins should not be disturbed when mak-
ing the adjustment to compensate for lining wear.
A leak in the pipe connections will allow the pedal, under
pressure,, to go gradually to the toe board. A cup leak
does not necessarily result in .loss of pedal travel, but is
indicated by a loss of fluid in the supply tank. If no
leaks are found either at the wheels or the connections,
the master cylinder should be removed and the bore
checked for scratches and scores.
Air in the brake system will cause a springy, rubbery action
of the brake pedal. If a sufficient quantity of air is
present in the system, the brake pedal will go to the toe
board under normal pressure. A l l air in the brake sys-
tem must be expelled by bleeding as explained in Note 5.
The fluid level in the supply tank should be checked.
Should the tank become empty, air will be introduced
into the system, necessitating bleeding as explained in
Note 5.
Mineral base oil, such as engine oil and kerosene, when
present in the brake system will cause the cylinder cups
to swell and bind, making it necessary to replace all
rubber parts. T o correct this condition, the brake system
should be flushed with alcohol and refilled with Special
N o . 5 brake fluid.
It is imperative that the port directly ahead of the master
cylinder piston cup be open when the brakes are released.
Should this port be blocked by the piston cup not return-
ing to its proper release position, the pressure in the sys-
tem will gradually build up, forcing all brakes to drag.
Loosening one of the bleeder screws at the wheels will
relieve the system of pressure and give temporary relief.
The bleeder screw must be tightened before the car is
driven.
Replace spring with a new one.
Readjust shoes to eliminate dragging as outlined in Note 2.
The rubber cylinder cups will swell and become distorted
if kerosene, gasoline or any other similar fluid is used
instead of alcohol to flush the brake system or to clean
these parts. Under this condition the return action of
the shoes will be retarded and the brake drums will heat.
T h e remedy is to replace the cups with new ones, wash-
ing them and flushing the brake system with alcohol and
then to dip the new parts in brake fluid before reassem-
bling them.
Loose or defective wheel bearings.
Adjust or replace bearings with new ones as necessary.