User's Manual

32
•
NITRO 4-TEC 3.3
ADJUSTING YOUR NITRO 4-TEC 3.3
Gear Ratios
Another Nitro 4-Tec 3.3 feature is the ability to change the gear ratios.
Currently, there are three optional gear ratios for the Nitro 4-Tec. The
stock gear ratio will provide very high (70+ MPH) top speeds. The
following gear ratio chart shows the available combinations with
optional spur gears and clutch bells.
Nitro 4-Tec gear ratios must be changed as 1st and 2nd gear sets in
order to maintain compatible gear center distances. The gear ratio
chart gives the only four compatible ratio choices.
Changing the Clutch Bell Gears
1. Remove the right, rear wheel. Remove the E-clip
from the two-speed shaft. Slide the pulley and belt off
of the shaft, being careful not to lose the pin that sits
under the pulley. Remove the pin. Slide the spur gears
off of the shaft (If you are using optional gears, you may
have to loosen the right chassis stiffener to remove the
spur gears).
2. Lock the flywheel with a
flathead screwdriver to
immobilize it. Use a 2.5mm
hex wrench to unscrew
the caphead screw that
holds the clutch bell to the
pilot shaft. Remove the
clutch bell.
3. To separate the gears from the clutch
bell, gently grip the clutch bell with
channel-lock, adjustable pliers. Cover the
gears with a cloth to protect the teeth.
Using the pliers, unscrew the gears
counter-clockwise.
4. New clutch gears simply screw onto the clutch bell. Reinstall the
clutch bell and caphead screw onto the pilot shaft. Reinstall the spur
gears, pin, pulley and belt. Secure them on the two-speed shaft with
the E-clip.
5. To adjust the gear mesh, first loosen the four 3x10 countersunk
hex screws in the slotted holes in the bottom of the chassis.
Next, loosen the two countersunk hex head screws in the bottom
of the chassis which hold the slotted engine mount. The engine
should now slide back and forth. Slide a strip of thin note paper
between the spur gears and the clutch bell gears. Push the clutch
bell gears against the spur gears and tighten the screws on the
bottom of the chassis. Remove the paper and the gear mesh is now
correctly adjusted.
Gear Clutch Spur Primary Overall
Teeth Teeth Reduction Reduction
Nitro 4-Tec Stock 1st 15 45 3.00 5.10
Equipment 2nd 19 41 2.16 3.67
Explosive acceleration
Optional Clutch Gears 1st 16 45 2.81 4.78
w/Stock Spur Gears 2nd 20 41 2.05 3.49
Very good acceleration
Stock Clutch Gears 1st 15 41 2.73 4.65
w/Optional Spur Gears 2nd 19 37 1.95 3.31
Good acceleration
Optional Clutch Gears 1st 16 41 2.56 4.36
w/Optional Spur Gears 2nd 20 37 1.85 3.15
Moderate acceleration