PRIMAAX
®
EX / PRIMAAX
®
for International Truck Vehicles
17730-283
31
Preventive Maintenance
LONGITUDINAL AND TRANSVERSE TORQUE RODS
PRIMAAX EX / PRIMAAX SUSPENSIONS INCORPORATE TRANSVERSE RODS FOR VEHICLE STABILITY. IF
THESE COMPONENTS ARE DISCONNECTED OR ARE NON-FUNCTIONAL THE VEHICLE SHOULD NOT
BE OPERATED. FAILURE TO DO SO CAN RESULT IN ADVERSE VEHICLE HANDLING AND POSSIBLE TIRE
CONTACT WITH THE FRAME. OPERATING A VEHICLE WITH NON-FUNCTIONAL TRANSVERSE TORQUE
RODS CAN RESULT IN LOSS OF VEHICLE CONTROL, SEVERE PERSONAL INJURY, AND PREMATURE
COMPONENT DAMAGE.
NOTE
Hendrickson recommends the use of Grade 8 bolts and Grade C locknuts for all straddle mount
torque rod attachments.
Visually inspect torque rod bushings
for torn or shredded rubber, inspect for bent, cracked, or
broken torque rods, and for end hubs with an elongated “oval” shape. Any of these conditions
will require component replacement.
Torque rod looseness
inspection is necessary per one of the following methods below.
■
Method 1
— for tractor applications only with brakes applied, slowly rock the empty vehicle
with power while a mechanic visually checks the action at both ends.
■
Method 2
— with the vehicle shut down, a lever check can be made with a long pry bar
placed under each rod end and pressure applied.
TORQUE ROD LENGTH
Longitudinal torque rod
length is determined by the truck manufacturer for optimum driveline
angles. The longitudinal torque rods along with the bottom caps maintain these angles and
control acceleration and brake forces, refer to the Pinion Angle Table in the Parts Lists Section of
this publication.
Transverse rod
length is also determined by the vehicle manufacturer to center the axles under
the frame.
■
If the lateral alignment of the axles is incorrect, it may be necessary to shim the transverse
torque rod at the straddle mount end. Shims can be installed between the transverse torque
rod and the transverse torque rod frame bracket or between the transverse torque rod and
axle tower bracket. Refer to vehicle manufacturer for proper shim location; also see Lateral
Alignment in the Alignment & Adjustments Section of this publication.
■
The transverse torque rods also control axle walk-out during cornering. The mounting brack-
ets at the axle housing end of the torque rods are furnished and welded into position on the
axle housings by the axle or vehicle manufacturer.
Transverse and longitudinal torque rods
have attaching ends designated as “straddle mount,”
“tapered stud,” or “through bolt” as shown in Figures 6-14 and 6-15. Most can be replaced by
pressing out the worn torque rod bushing and installing a replacement bushing, others require
complete torque rod assembly replacement.
FIGURE 6-14
FIGURE 6-15
NOTE
Some torque rods assemblies equipped on PRIMAAX EX / PRIMAAX suspensions have curled end
hubs and are not re-bushable. The entire torque rod assembly must be replaced. This feature
provides superior bushing retention in the torque rod end hub.
Pro Gear and Transmission • 906 W. Gore St. Orlando, FL 32805 • 1 (877) 776-4600 / (407) 872-1901 • [email protected]
