Nissan trucks use a torsion bar suspension at the front end rather than a torsion beam. In this system, a bar and lever support most of the truck's weight. The exact position and height of the bar is essential if you are replacing the torsion bar on your Xterra yourself. Once replaced, you should have a mechanic confirm the ride height. This height (along with the replacement process) can vary depending on the exact year of the truck.
Raise the Xterra and support it on jack stands. Remove the wheel.
Slide the rubber boot off the torsion bar's flange and mark the bar's relationship to the anchor arm and torque arm with whiteout or paint. Measure and record how far the adjusting bolt protrudes out from its washer.
Remove the adjusting bolt locknut on the anchor arm; hold the adjusting nut with one wrench while you remove the locknut with a second wrench.
Lubricate the adjusting bolt's threads with grease and then unscrew the bolt with your wrench. Remove the bolt and nut once the nut nears the end of the bolt, relieving all pressure from the torsion bar at this point.
Unbolt the lower control arm from the torque arm, then slide the torsion bar forward until it clears the crossmember. Lower the rear end and remove the torsion bar with the torque arm.
Compare the replacement torsion bar with the old one and apply matching alignment marks to the replacement. Apply a thin coat of moly-based grease to each end of the replacement torsion bar on the splines.
Raise the bar's rear end into position and connect the torsion bar and torque arm, then slide the torsion bar over the crossmember and bolt the torque arm to the lower control arm.
Insert the adjusting bolt and nut and tighten the bolt with the wrench until it reaches the same distance as you recorded earlier. Slide the rubber boot in place on the flange connected to the anchor arm.
Lower the truck off the jack stands.
Bounce the truck's front end several times and then roll the truck back and forth to settle the suspension.
Apply and tighten a new locknut on the adjusting bolt
