SECTION 16: SUSPENSION
DOB 2490-2789 | X3-45 Commuter PA1605 Maintenance Manual (Section 16 revised April 2019)
19
height control valves. The two rear valves are
mounted to the subframe and connected to the
rear axles through an arm and link connection.
The front valve is mounted to the subframe and
connected to the front air tank support. These
connections allow the valves to apportion air
pressure in the springs to the vehicle load,
maintaining normal ride height.
Immediate response height control valves
increase or decrease the air pressure in the
suspension system as required. One height
control valve is located
at center of front sway
bar
, and regulates air to front suspension air
springs in order to maintain the vehicle at the
required height. Two are located at the drive
axle, one on each inner side of rear
wheelhousing.
The appropriate vehicle body height is obtained
by measuring the clearance of all the air springs
installed on the vehicle. Refer to Figure 17,
Figure 18, Figure 19, to identify the correct area
to take measurement and proper value. At this
point, it should not be necessary to make an
adjustment under normal service conditions.
However, if an adjustment is required, change
the position of the overtravel lever in relation to
the overtravel control body. The lever should be
moved up to raise vehicle height, and down to
lower it. Check that main air pressure is at
normal operating pressure and raise the vehicle
to the specified height.
FIGURE 17:
FRONT I-BEAM AXLE AIR SPRING
CLEARANCE
FIGURE 18: DRIVE AXLE AIR SPRING CLEARANCE
16195
FIGURE 19: TAG AXLE AIR SPRING CLEARANCE
16195
CAUTION
Always adjust on "fill cycle". If it is necessary
to lower vehicle height, release sufficient air to
be well below height, and adjust to height or fill
cycle.
FIGURE 20: FRONT HEIGHT CONTROL VALVE
16100
The normal ride height is obtained by adjusting
air spring clearance of both front and rear
suspension as follows:
Front I-beam axle air spring clearance
1. With the vehicle at normal operating air
pressure [100 - 125 psi (689 - 860 kPa)],
measure air spring clearance. This
