Cub Cadet 4 x 4 Volunteer - Manual (Page 181)

Chapter 6 - Hydraulic Brakes
177
BRAKE SYSTEM DIAGNOSIS
Soft Pedal
• Leakage: Make a visual inspection of the com-
plete system. Pay attention to the back of the
master cylinder, the calipers, and all the connec-
tion points in the system. Leaks are sometimes
easier to find before the vehicle is cleaned.
Check the master cylinder fluid level. If both
sides of the reservoir are low, the leak may be
where the push-rod enters the back of the mas-
ter cylinder. If only one side of the reservoir is
low, use that information to direct the search.
Tracking fluid up from a puddle can also assist in
finding a leak.
A clean cap on the reservoir is an indication that
the operator may have added, or at least
checked, the fluid level.
• The master cylinder should be capable of pro-
ducing about 1,500 psi.(103 Bars) of hydraulic
force. If there is no leakage, but the pedal is
soft, there may be blow-by at the internal
seals in the master cylinder bore. If the shop is
not equipped with pressure gauges to connect to
the master cylinder, it is necessary to use the
process of elimination. If none of the remaining
causes in the section are causing the problem, it
is likely to be the master cylinder.
• Caliper frozen on slide pins: After a long
period of dis-use or extremely gentle use, the
calipers may have become stuck on the slide
pins by corrosion or debris.
When pressure is applied to the piston in the cal-
iper, the inside pad contacts the rotor, and the
body of the caliper normally slides in the oppo-
site direction, pulling the second brake pad
against the outside of the brake rotor.
If the caliper does not slide, the force applied to
the piston will bow the caliper bracket and may
bow the rotor. The “giving” and springing-back
of the metal parts will cause a soft pedal. This
situation is easily identified by visual inspection
while an assistant works the brake pedal.
• Air in the system: Unless caused by leakage,
this condition will follow any service that requires
the opening of the hydraulic system. The sys-
tem should be bled after any such repair. It
bleeds easily, and should not present an obsta-
cle for most technicians.
• High temperature fade: Results from boiling
fluid under extremely heavy use. This should
not be an issue in any reasonable operation of
the vehicle.
Firm pedal but poor brake performance
• Friction surface problems are the most likely
cause of this situation. Clean any liquids off the
brake rotor, and identify the source of those liq-
uids. If the source is an oil or gear lube leak,
repair it to prevent reoccurrence. If the pads are
contaminated, replace them.
• If the situation is accompanied by a screeching
noise, and comes-on suddenly, a small stone
may have become trapped between the brake
pad and the rotor. Loosen or remove the cali-
per to dislodge the stone before it damages the
rotor. This is a highly unusual problem, but it can
occur.
• After many hours of use, the pads will wear.
Worn pads will allow the brake pad wear indica-
tors to touch the rotors, causing a squeaking
sound. This sound is a normal indication that
the brakes need service.
Pedal pulsation
• Warped brake rotor. Check rotors for run-out
using a dial indicator, Once the warped rotor is
identified, replace it.
• Variations in friction around the surface of the
rotor can cause similar stopping characteristics
to a warped rotor, but without actual pulsation of
the pedal. This issue is usually caused by rust
spots or foreign material on the surface of the
rotor. These symptoms will usually go away with
use.