GMC 1976 ZEO 6083 Maintenance Manual page 192

4- 8 REAR SUSPENSION
Figure 10-Height Control Valve Ports
6. Remove mounting brackets, safety valve, and
Schrader valve. Remove drain cock if reservoir is so
equipped .
HEIGHT CONTROL VALVE
REMOVAL
Before disconnecting any height control valve air
lines, securely support frame to prevent it from low-
ering as air is released from suspension . Exhaust air
from air supply system by opening schrader valve on
air reservoir. After the above precautions have been
taken, remove height control valve as follows :
Figure 1 1-Disconnecting Height Control Valve Link
1. Disconnect height control valve overtravel
lever from valve link . Pull lever downward and hold
several seconds to overcome time delay feature ; This
will release compressed air from bellows.
2 . Referring to Figure 10, disconnect air supply
line and bellows air line from height control valve.
Tape ends of lines to prevent foreign material from
entering .
3 . Remove two nuts attaching height control
valve to wheel well and remove valve assembly .
AIR BELLOWS REMOVAL
1 . Support vehicle on jack stands .
2 . Referring to Figure 11, disconnect leveling
valve link and move arm down to open exhaust valve
and let air out of bellows.
3. Referring to Figure 12, disconnect air line to
bellows.
4. Referring to Figure 13, remove retaining nuts
and washers.
5. Remove air bellows from vehicle.
CONTROL ARM REMOVAL
1 . Raise vehicle until rear wheels are off the floor.
Figure 12-Disconnecting Bellows Air Line