9
Tuning the Engine by Temperature
The following procedures require an optional infrared temperature
probe, an on-board temperature gauge, or the Traxxas telemetry
temperature sensor, part #6521. The engine can be used as an
effective tuning aid when you understand the relationship between
engine temperature and ambient temperature.
The engine operating temperature, when tuned for maximum
performance, will vary according to atmospheric conditions. The
atmospheric condition that has the most influence on engine
temperature is air temperature. Expect the engine temperature
to vary almost in direct proportion to atmospheric temperature.
Assuming you tuned the engine for the same maximum
performance each day, the engine will run about twenty degrees
hotter when it’s ninety degrees outside than it would in seventy-
degree weather. For this reason, we cannot give you a definitive
temperature range that indicates the best possible engine tuning.
The temperature gauge can aid you in tuning by giving you a
relative indication of how your adjustments are affecting the
engine and by preventing you from exceeding maximum engine
temperature. For example, as you lean the fuel mixture, the engine
performance will increase along with the temperature. If you
continue to lean the fuel mixture and the temperature increases but
the engine performance does not change, then you have exceeded
the maximum safe lean setting.
If tuning for maximum performance results in engine temperature
exceeding 300°F, try to increase airflow to the engine by cutting out
the rear of the body, windshield, and front valance. If the engine
temperature still cannot be kept in check, richen the high-speed
needle slightly.
Adjustments
Toe-in
Geometry and alignment specifications play an important role in
your truck’s handling, so take the time to set them correctly. Set the
steering trim on your transmitter to neutral. Now, adjust your tie rods
so that both wheels are pointing straight ahead and are parallel to
each other (0° toe-in). This will ensure the same amount of steering in
both directions. If you run out of adjustment, then the steering servo
will have to be re-centered (see “Centering your Servos” on page 10).
For increased stability add 1°- 2° of toe-in to each front wheel. Use
the turnbuckles to adjust the alignment.
Camber
The camber angle of both the front and rear wheels can be adjusted with
the camber rods (upper turnbuckles). Use a square or right-angle triangle
to set the camber accurately. Adjust the front wheels to 0° of camber
(wheel perpendicular to the ground). In the rear, adjust the wheels to
1° to 2° of negative camber. These adjustments should be set with the
truck positioned at its normal ride height.
Shocks
The four shocks on Nitro Sport have the
most influence on its handling. Whenever
you rebuild your shocks or make any
changes to the pistons, springs or oil, always
do it carefully and in pairs (front or rear).
Piston selection depends on the range of
oil viscosities that you have available. For
example, using a two-hole piston with a
lightweight oil will, at one point, give you the
same damping as a three-hole piston with
heavier oil. We recommend using the two-
hole pistons with a range of oil viscosities
from 10W to 50W (available from your hobby
shop). The thinner viscosity oils (30W or less)
flow more smoothly and are more consistent,
while thicker oils provide more damping.
Use only 100% pure silicone shock oil to
prolong seal life.
The ride height for Nitro Sport can be adjusted by adding or
removing the clip-on spring pre-load spacers. Instead of adding
spacers to increase stiffness, use stiffer springs. Adjust the ride height
so that the suspension arms are slightly above being parallel to
the ground. Observe how the Nitro Sport handles in turns. If it is
picking up the inside rear wheel in hard turns, then stiffen the front
suspension. If it is picking up the inside front wheel in hard turns,
then stiffen the rear suspension. Proper set-up will add stability and
help prevent roll-overs.
Gear Ratios
A unique Nitro Sport feature is the ability to change the gear ratios.
The final drive ratio of the gearbox is 2.81 to 1. Use the following
formula to calculate the overall ratio:
Nitro Sport comes with a 70-tooth spur gear and a 20-tooth pinion
(clutch bell) gear. This combination will provide the best overall
acceleration and top speed. If you want more acceleration and less
top speed, then use a smaller clutch bell gear (fewer teeth). For more
top speed, use a larger clutch bell gear.
adjusting the Slipper Clutch
The Nitro Sport features an adjustable slipper clutch on the spur gear
to protect the drivetrain from sudden shock loads (such as landing off
of jumps with the engine at full throttle). Under normal conditions,
the slipper clutch should not slip. Before adjusting the slipper clutch,
turn the model off. Do not adjust the slipper clutch while the engine is
running.
Use the supplied wrench to tighten the slipper nut (clockwise) until
it stops, and then back the nut out 1/4 of a turn. If you notice any
decrease in performance after making changes to the slipper clutch
adjustment, then it may be too loose. The slipper must not be allowed
to slip during normal acceleration or the slipper could be damaged.
PRE-lOaD
SPaCERS
Pinion
22
22
22
20
20
18
18
16
16
Spur Gear
66
70
72
70
72
70
72
70
72
Final Drive
8.43:1
8.94:1
9.19:1
9.83:1
10.11:1
10.92:1
11.24:1
12.27:1
12.64:1
aCCElERaTION
TOP SPEED
Number of
Spur
Gear Teeth
Number of
Clutch
Bell
Gear Teeth
x 2.81 =
Final Drive Ratio
0
°
0
°
1
°
-2
°
1
°
-2
°
-1
°
-1
°
Toe
0
°
0
°
1
°
-2
°
1
°
-2
°
-1
°
-1
°
Camber