30 • DESERT RACER
5. Install the X-ring over the shaft and into the bore of the shock body.
6. Install the lower cap using the suspension multi-tool (B).
7. Grip the shaft close to the threads with needle nose pliers or side
cutters and thread the rod end onto the shock shaft until the rod
end bottoms out (C).
8. Fill the shock with new silicone shock oil up to the top of the
shock body. Slowly move the piston up and down (always keeping
it submerged in oil) to release the air bubbles. Let the shock sit for a
few minutes to allow any remaining air bubbles to surface.
9. Slowly thread the upper cap with the installed shock bladder onto
the shock body with the suspension multi tool (A). The excess oil
will bleed out of the small hole in the shock cap. Tighten the shock
cap until snug. Use the included steel shock wrench to hold onto
shock body while tightening.
10. Reinstall the spring and lower spring retainer. Reinstall the
2.5x10mm cap screw.
Tuning the Front Sealed Gear Differential
The Ultimate Desert Racer’s front gear differential allows the left
and right wheels to spin at different speeds while turning so that
the tires do not scuff or skid. This decreases the turning radius and
increases steering performance.
The performance of the front differential can be tuned for different
driving conditions and performance requirements. The differential is
filled with silicone differential fluid, and is sealed to maintain consistent
long-term performance. Changing the oil in the differential with either
lower or higher viscosity oil will vary the performance characteristics of
the differential. Changing to a higher viscosity oil in the differential will
reduce the tendency for engine power to be transferred to the wheel
with the least traction. You may notice this when making sharp turns
on slick surfaces. The unloaded wheels on the inside of the turn have
the least traction and tend to spin up to extremely high rpms. Higher
viscosity (thicker) oil causes the differential to act like a limited-slip
differential, distributing more equal power to the left and right wheels.
Your Desert Racer will generally benefit from higher viscosity oil when
climbing, rock crawling, or racing on low traction surfaces.
Note:
Heavier oil will allow power to be transferred even with one or
more tires off the ground. This can make the vehicle more likely to
overturn.
From the factory, the front differential is filled with SAE 30,000W
viscosity silicone oil. Only use silicone oil in the differential. Traxxas
offers SAE 10,000W and 50,000W viscosity oil (see your parts list). The
differential has to be removed from the vehicle and disassembled to
change/replace oil.
ADVANCED TUNING ADJUSTMENTS
Never slide the threads on
the shock rod past the X-ring
seal when it is installed and
compressed by the bottom
cap of the shock. Doing so will
damage the seal and cause
shock oil to leak.