GMC 1976 ZEO 6083 Maintenance Manual page 209

b. Being careful not to disturb indicator set-
ting, disconnect air supply from the air inlet port and
connect it to the bellows port (figure 50).
c. Move overtravel lever slowly to open ex-
haust port while observing the indicator dial . Air
should start to escape from exhaust port when in
dicator registers 0.035" to 0.037". If adjustment is
necessary, shut off air pressure supply and remove
valve cover. Bend lever to correct setting, then install
cover and recheck valve opening dimension.
d. Recheck valve lever gaps, then proceed
with "TIME DELAY CHECK" following:
TIME DELAY CHECK
Preliminary Procedures
After the valve lever gaps have been adjusted, do
the time delay check. A 4 to 18 seconds delay from
the closing of one valve to the opening of the other
is recommended . Also, valves should close from full-
open position within 4 seconds .
1 . Pour 5.5 cc -+ 0.25 cc of Silicone fluid (3,000
Centistokes viscosity at 25°C .) into delay piston bore .
With valve body tilted slightly, as shown in Figure
54, carefully operate overtravel lever fore and aft to
vent air from fluid. When all air has been expelled
from piston pin cavity, check fluid level (figure 55).
VALVE BODY TILTED
UPWARD AT THIS END
Figure 54-Venting Air From Silicone Fluid
REAR SUSPENSION 4- 2 5
Figure 55-Silicone Fluid Level
IMPORTANT:
With valve assembly level, take.
measurement from center of bore only . Add or
Remove fluid to bring fluid to dimension shown
in Figure 55 . An eyedropper will serve for this
purpose.
2. Place new delay piston cover O-ring in groove
of valve body . Install cover with retainer .
3 . Place valve assembly vertically in holding vise
(figure 56).
4. Cycle arm up and down for approximately one
minute .
Figure 56-Valve Positioned for Time Delay Check