ARBOC Spirit 2015, Service & Operation Manual

Page: 91 / 195

Revised: 5/22/2015 Page 91
MAINTENANCE
Rear Suspension U-Bolt Service Recommendations (Spirit of Mobility)
By following the service tips outlined below, many of the common problems associated
with U-Bolts can be avoided.
DO NOT REUSE U-BOLTS

Used U-bolts will have rusted and damaged threads from the previous
installation.

A previously torqued U-bolt will suffer from distorted threads from the
engagement of the deep nut. Deep nuts should be tightened once and
retorqued, never loosened and retightened.

A used U-bolt may have suffered from fatigue as well excessive stress since
achieving accurate torque with commonly used impact wrenches is very difficult.
The primary function of the U-bolt is to maintain the clamping force on the assembly.
Since clamping force is a function of the condition of the U-bolt, the damaged threads of
the used U-bolt will make reaching the force necessary, very difficult. Considering that
reusing U-bolts can lead to premature failures, it is clear that U-bolts should never be
reused.
Retorque the U-bolts
It is recommended that U-bolts be retightened after 1,000, 3,000, and 24,000 miles as
components wear in or settle. Even a minor amount of this settling can cause a
dramatic reduction in U-bolt clamping force. If possible, retorquing of U-bolts should be
done with the vehicle under load.
Torque U-bolts Evenly

Lubricate U-bolts and washers with oil or anti-seize
compound to reduce nut friction.

Tighten all U-bolts until they are snug.

Tighten in the sequence shown to approximately 1/3
of recommended torque.

Repeat, using the same sequence, gradually
increasing the torque through a second and third stage until
the recommended final torque (175-185 foot/pounds) is
achieved.