Master Cylinder; Brake Fluid; Master Cylinder Replacement; Replacing Master Cylinder - Ezgo WorkHorse ST 480 Technician's Repair And Service Manual

Read all of Section B and this section before attempting any procedure. Pay particular attention to all Notes, Cautions and Warnings
After making any repairs to hydraulic lines, wheel cylin-
ders or master cylinder, the brakes must be bled to
remove any trapped air. A bleeder valve is located at
each wheel cylinder for this purpose. See 'BLEEDING
AND FLUSHING' on page D-9.

MASTER CYLINDER

Just like any other brake part, the master cylinder will
eventually require replacement. The usual reason for a
master cylinder failure is the cylinder seals (cups) deteri-
orate. Fluid leaks past the cups and shows as an exter-
nal leak. A common symptom is a 'spongy' brake pedal
that goes all the way to the floor when all the other brake
components are in good condition. The rubber parts wear
with usage or deteriorate with age or fluid contamination.
Corrosion or deposits formed in the cylinder bore due to
moisture or dirt in the hydraulic system may result in
wear of the cylinder bore or related parts. Do not try to
remove corrosion or deposits with a cylinder hone. If cor-
rosion or deposits are present, discard master cylinder
and replace with new one.

Brake Fluid

Hydraulic brake systems must be totally
flushed if the fluid becomes contaminated with
water, dirt or other corrosive chemicals. To flush, bleed the
entire system until all brake fluid has been replaced with fresh
DOT 3 standard automotive brake fluid.
It is important to maintain proper fluid levels in the master
cylinder. The fill cap for the cylinder is located under the
driver seat. To prevent contamination when checking
fluid, wipe off any dirt from fill cap before removing it.
Reservoir fluid level should be checked per 'PERIODIC
SERVICE SCHEDULE' in Section A. When required,
clean brake fluid should be added to maintain fluid level
1/4" (6 mm) from top of reservoir. Use fresh DOT 3 stan-
dard automotive brake fluid.

Master Cylinder Replacement

Tool List
Insulated wrench, 1/2"................................................. 1
Shop towels ............................................................ A/R
Catch pan.................................................................... 1
Wrench, 3/8" ............................................................... 1
Wrench, 5/8" ............................................................... 1
Needle nose pliers ...................................................... 1
Wrench, 9/16" ............................................................. 2
Wrench, 1" .................................................................. 1
Wrench, 7/16" ............................................................. 1
Teflon tape............................................................... A/R
Crowfoot wrench, 1", 3/8" drive ................................... 1
Torque wrench, in. lbs., 3/8" drive ............................... 1
Socket, 7/16", 3/8" drive .............................................. 1
Crowfoot wrench, 5/8", 3/8" drive ................................ 1
Socket, 9/16", 3/8" drive .............................................. 1
!
of a dropped wrench 'shorting out' a bat-
tery, which could result in an explosion and
severe personal injury or death.
master cylinder. Avoid allowing brake fluid to con-
tact the painted body components of the vehicle.
Wipe off immediately.
Turn vehicle key to 'OFF' and remove. Insure all optional
electrical accessories are turned OFF. At the battery,
remove the negative (-) cables. Cover top of battery with
a cloth or non-conductive material to prevent the possibil-
ity of a dropped wrench or metal object from 'shorting
out' the battery.
Clean the area around the master cylinder to prevent dirt
and grease from contaminating the hydraulic system.
Disconnect wire terminal block from brake light switch on
top of branch tee (Ref Fig. 2 on page D-3).
Qty. Required
Linkage
Repair and Service Manual
!
During this process, it is likely
that brake fluid will leak from the
Push Rod
Clevis Yoke Rubber
Boot
Washer
Bell
Crank
Rod Part of
Clevis Frame
Yoke
Washer
Fig. 2 Replacing Master Cylinder
BRAKES
Wrap wrenches with
v i n y l t a p e t o p r e -
vent the possibility
Brake
Light
Branch
Switch
Tee
Plug
Lock
Nut
Clip
Flexible
Brake
Hose
To
Primary Brake
Line
Page D-3