Chrysler 1998 Voyager Service Manual page 98

5 - 16 BRAKES
DIAGNOSIS AND TESTING (Continued)
Fig. 17 Minimum Rotor Thickness Markings
micrometer at a radius approximately 25.4 mm (1
inch) from outer edge of rotor (Fig. 18). If thickness
measurements vary by more than 0.013 mm (0.0005
inch), rotor should be removed and resurfaced, or a
new rotor installed. If cracks or burned spots are evi-
dent, rotor must be replaced.
Fig. 18 Checking Rotor For Thickness Variation
Light scoring and/or wear is acceptable. If heavy
scoring or warping is evident, the rotor must be
refinished or replaced (See Refinishing/Refacing
Rotor). If cracks are evident in the rotor, replace the
rotor.
PROPORTIONING VALVES
FIXED PROPORTIONING VALVE TEST
PROCEDURE
On a vehicle equipped with ABS, premature or
excessive rear wheel ABS cycling may be an indica-
tion that the brake fluid pressure to the rear brakes
is above the desired output.
Prior to testing a proportioning valve for function,
check that all tire pressures are correct. Also, ensure
the front and rear brake linings are in satisfactory
condition. It is also necessary to verify that the
brakes shoe assemblies on a vehicle being
tested, are either original equipment manufac-
turers (OEM), or original replacement brake
shoe assemblies meeting the OEM lining mate-
rial specification. The vehicles brake system is
not balanced for after market brake shoe
assembly lining material.
If brake shoe assembly lining material is of satis-
factory condition, and of the correct material specifi-
cation, check for proper proportioning valve function
using the following procedure.
(1) Road test vehicle to be sure the vehicle is truly
exhibiting a condition of excessive rear wheel ABS
cycling. Since ABS cycles both rear brakes together
both proportioning valves of the assembly (Fig.
19) must be tested. Use the following procedure to
test the proportioning valve.
Fig. 19 Rear Brake Proportioning Valve And Brake
Tube Locations
(2) Remove one of the chassis brake lines (Fig. 19)
coming from the ABS modulator, at
(3) the proportioning valve assembly. Remove the
hydraulic brake line going to one of the rear wheels
of the vehicle from the proportioning valve (Fig. 19)
NS