Peterbilt Medium Duty Truck Owner's Manual - Peterbilt Motors

Rear Axle and Suspension
It is important that U–bolts remain tight. Severe use of your
vehicle can cause them to loosen faster. But all vehicles need
to have their U–bolts checked and tightened regularly. Be
sure someone with the proper training and the right tools
checks and tightens the U–bolts on your Medium Duty vehicle.
New springs “settle-in” after the vehicle's initial service, causing
the U–bolts to become loose. After the first 500 miles
(800 km) of operation, inspect the suspension periodically, as
noted below:
• Visually check for loose or missing fasteners, cracks in
hanger or axle connection brackets.
• Check that springs are centered in hangers and in good
condition.
• Check for cracks, wear marks, splits, or other defects on
the surface of the spring.
• Replace defective parts. Because repaired springs cannot
be fully restored to their original service life, replace
the complete assembly if cracks or other defects are
detected.
• After replacement of any part or discovery of loose components,
check the torque of all fasteners.
Rear Axle Lubrication
Preventive Maintenance
• Check oil level with the vehicle parked on level ground
and the fluid warm. The level should be even with the
bottom of the filler hole.
CAUTION: Do not mix lubricants of different
grades; although, mixing different brands of the
same grade lubricant (meeting MIL–L–2105–C),
is acceptable. Lubricants of different grades are
not compatible and could damage the axle.
NOTE: In all cases, the lubricant supplier assumes
full responsibility for the performance of their product,
and for product and patent liability.
Initial Change: Change lubricant in new or rebuilt axle
assemblies within the first 3,000 to 5,000 miles (4800 to 8000
km). For recommended types and brands of lubricants, contact
your Peterbilt Dealer or Authorized Service Center. See
the Medium Duty Maintenance Manual and the axle manufacturer's
Service Manual for further information on servicing
drive axles.
– 250 – Y53-6027 Medium Duty (R05/09)