SECTION 16: SUSPENSION
18
DOB 2490-2789 | X3-45 Commuter PA1605 Maintenance Manual (Section 16 revised April 2019)
SPECIFIC TORQUE TABLE 3 – REAR SUSPENSION
REFERENCE
DESCRIPTION
TORQUE DRY
(lbf-ft / Nm)
1
Air Spring Upper & Lower Stud Nut (6 air springs)
31-38
42-52
2
Drive & Tag Axle Radius Rod threaded stud (12 supports)
90-110 122-149
3
Sway Bar Link Upper & Lower Nut
99-121
134-164
4
Shock Absorber Pin Nut (6 shock absorbers)
99-121
134-164
5
Shock Absorber Pin (6 shock absorbers)
350-400 475-545
6
Drive axle Radius Rod Nut/bolt (6 supports)
225-255
305-346
7
Drive Axle Radius Rod Retaining Bolts (2 longitudinal radius rods)
171-209 231-283
8
Tag Axle Radius Rods Nut (6 supports)
228-252
309-341
9
Sway Bar Bushing Collar Bolt
80-100
108-136
10
Tag Axle Transversal Radius Rod (Casting) Retaining Bolt
171-209
231-283
11
Sway Bar Link Pin Stud
350-400 475-545
12
Shock Absorber Lower Nut (6 shock absorbers)
60-75 81-101
NOTE
Apply corrosion-protective compound on exposed threads.
5. SUSPENSION AIR SYSTEM
The suspension air system has its own air
reservoir (accessory tank) which is located in the
reclining bumper compartment. Pressurized air
from the main tank (wet tank) flows through a
pressure protection valve (PR-4), to the
accessory air tank and through an air filter which
is located in front service compartment.
The pressure protection valve (PR-4) is mounted
to the supply port of the tank. This valve controls
the pressure at which compressed air is
delivered to the accessory air tank. The valve
remains closed until a preset pressure is
reached (approximately 70 psi (485 kPa)). It
then opens and passes air out the delivery port.
The main use for this valve is to protect the main
air system by ensuring at all times a sufficient air
pressure in the main system (i.e. air delivered to
the accessories will be shut off in case of a
decrease in pressure). Maintenance and repair
information on the pressure protection valve is
supplied in the applicable booklet, under
reference number SD-03-2010.
WARNING
Depressurize parts prior to removal.
5.1 INSPECTION
The following inspection should be performed at
established service inspection periods.
Performing these procedures will allow
substandard performance to be discovered
before the condition becomes bad enough to
cause operator complaints and failure on a run.
1. Visually inspect the suspension air lines for
evidence of chafing on metal parts or other
damage.
2. Visually inspect the air springs for cracks,
abrasion or other damage.
3. Replace any parts found to be damaged.
5.2
AIR LINE TEST
With the main air system at normal operating
pressure, coat all suspension air line
connections and air spring mountings with a
solution of soap and water. Air leakage will
produce soap bubbles. Any leak found must be
corrected as no air leakage is permissible.
6. SUSPENSION
HEIGHT ADJUSTMENT
The flow of pressurized air from the accessory
air tank to the air springs is controlled by three
