SECTION 16: SUSPENSION
4
DOB 2490-2789 | X3-45 Commuter PA1605 Maintenance Manual (Section 16 revised April 2019)
2. Exhaust compressed air from accessory air
tank by opening drain cock under reservoir.
3. Disconnect the height control valve link and
pull down the overtravel lever to ensure all
air is exhausted from air springs.
NOTE
While performing this step, do not change the
height control valve overtravel lever
adjustment.
4. Disconnect air line from air spring and cover
both the line end and fitting to prevent the
entry of foreign matter.
5. Unscrew the two air spring lower mounting
nuts.
6. Rotate the air spring counterclockwise to
free the upper attachments from the
mounting plate.
7. Remove the air springs.
FIGURE 3: AIR SPRING UPPER MOUNTING PLATE
2.1.3
Installation
1. Compress air spring as necessary and
position air spring between both the lower
and upper mounting plates.
2. Align the upper attachments with holes in
the mounting plate. Rotate air spring
clockwise.
3. Thread the lower nuts a few turns.
NOTE
To facilitate air spring installation, compress it
manually then put a piece of tape over the air
line threaded fitting. This prevents air from
getting back into the air spring and keeps it
compressed, thus enabling to place the air
spring in between the mounting plates and
greatly easing installation.
4. Tighten and torque the lower stud nuts
according to Torque Table under heading
Torque Specifications.
5. Install fitting (if applicable), then connect air
line.
6. Connect the height control valve link.
7. Build up air pressure in system.
NOTE
To accelerate this operation, air reservoirs can
be filled from an exterior air supply connected
to the accessory tank fill valve or to the
emergency fill valve.
7. Check operation of bellows and with the
primary air system at normal operating
pressure (95 – 125 psi (655 – 860 kPa)),
coat the air line connections and air spring
mounting areas with a water and soap
solution. Bubbles will indicate an air leak,
and none is permissible. Repair or replace
defective parts.
8. Reinstall
wheel.
9. Remove the hydraulic floor jack from under
the axle, then lower vehicle to ground.
2.2 SHOCK
ABSORBERS
Double-action, telescoping-type shock
absorbers ensure a smooth ride and enhance
vehicle stability on the road. All shock absorbers
are eye-type mountings. The front and tag axles
are each provided with two shock absorbers
while the drive axle is provided with four of them.
Shock absorbers are non-adjustable and non-
repairable. Maintenance requirements involve
replacement of the rubber mounting bushings,
and tightening of all shock absorber pins
according to Torque Table under heading
Torque Specifications when shock absorber
replacement occurs. If a shock absorber
becomes inoperative, complete unit must be
replaced.
CAUTION
When a shock absorber is found defective,
always replace with a new set on affected
axle, except if there has been a recent
replacement of one unit. The following method
will help in determining if both shock absorbers
on the same axle have to be replaced.
