Chrysler RAM TRUCK 2500 1994 Service Manual page 167

5 - 8 MASTER CYLINDER
M A S T E R C Y L I N D E R
INDEX
page
Brake Fluid Contamination 9
Brake Fluid Level 9
Description 8
Master Cylinder Application 8
Master Cylinder Bleeding (On Btench) . . . . . . . . . . 13
Master Cylinder Cleaning and Inspection 12
Master Cylinder Disassembly and Overhaul . . . . . . 11
page
Master Cylinder Identification Codes 8
Master Cylinder Installation 13
Master Cylinder Reassembly 12
Master Cylinder Removal 9
Master Cylinder Serviceability . . . . . . . . . . . . . . . . . 8
Recommended Brake Fluid . . . . . . . . . . . . . . . . . . . 9
DESCRIPTION
BR models are equipped with a Delco, two-section
master cylinder assembly. Major components are the
aluminum cylinder body and a removable plastic res­
ervoir (Fig. 1).
The primary and secondary pistons are located i n
the cylinder body. Grommets are used to secure and
seal the reservoir i n the cylinder body. The reservoir
cover is equipped with diaphragm seal and is a snap
fit on the reservoir.
The cylinder body is equipped with a quick take-up
valve located i n the primary piston inlet port (Fig. 1).
The valve provides an extra volume of low pressure
fluid during initial brake apply. Extra fluid volume
provides faster take-up of normal clearances i n the
calipers and wheel cylinders.
MASTER CYLINDER SERVICEABILITY
The cylinder body, piston assemblies, reservoir,
grommets, seal and cover are all serviceable parts.
The take-up valve is the only non-serviceable compo­
nent. The valve is available only as part of a com­
plete cylinder body assembly.
MASTER CYLINDER APPLICATION
Three master cylinders are used i n BR models. The
differences between them concern cylinder bore size
and fluid reservoir capacity.
• The master cylinder i n 1/2 ton (1500) models has a
28.6 mm (1.125 in.) bore.
• The master cylinder i n 3/4 and 1 ton (2500/3500)
models has a 31.8 mm (1.252 in.) bore.
Although the master cylinders used i n 3/4 ton and
1 ton models have the same bore size, they have dif­
ferent piston stroke lengths and fluid reservoir ca­
pacities. Refer to Brake Fluid Level and Master
Cylinder Identification i n this section for details.
Master cylinders and reservoirs must never
be interchanged. This practice will cause unsat­
isfactory operation and improper brake bal­
ance.
RESERVOIR
COVER
DIAPHRAGM
SEAL
RESERVOIR
TAKE-UP VALVE
(INSIDE BODY)
PISTON
SPRING
CYLINDER
BODY
SEAL
RETAINER
S N A P
R I N G
SECONDARY
PISTON
PRIMARY
PISTON
ASSEMBLY J9405-13
Fig. 1 Delco Two-Section Master Cylinder
MASTER CYLINDER IDENTIFICATION CODES
The master cylinder and reservoir are coded for
identification. Code letters are provided on the cylin­
der body and reservoir for proper component match­
ing.