XTM Racing Mammoth ST User manual

1
DISTRIBUTED EXCLUSIVELY BY
Global Hobby Distributors
18480 Bandilier Circle, Fountain Valley, CA 92708
All contents copyright © 2005, Global Hobby Distributors
Version V1.0 May 2005
Kit Product # 145619
OPERATION, TUNING GUIDE AND REPLACEMENT PARTS
MAMMOTH ST NITRO STADIUM TRUCK FEATURES:
●Factory-Built and Painted
●Powerful XTM Racing 24.7 Engine with Tuned Pipe
●Hitec Aggressor AM Radio System
●High-Torque Metal Gear Steering Servo
●2-Speed Transmission for Awesome Speed
●Low Center of Gravity for Awesome Handling
●Double Bracing Front and Rear
●New Upper Arm Design for More Precise Handling
●Full Ball Bearings
●Heavy-Duty Side Dust Guards
●3mm Aluminum Chassis with Curved Edges for Added Strength
●Large Front Bumper and Skid Plate
●Triple Vented Disc Brakes
●Chrome-Plated Universals and Dogbones for Added Strength
●Steel Differentials
●Gear Boxes Allow Easy Differential Removal
●3.5mm Rear Sway Bar
●Fully Threaded, Oil-Filled Aluminum Shocks with 3.5mm Shafts
●Dish-Style Racing Wheels with 17mm Hex Mounts
●Factory-Glued Tires with Inserts
●Adjustable Camber, Caster and Toe-In Front and Rear
●Water Resistant Receiver and Battery Boxes
✦✦
✦✦
✦IMPORTANT✦✦
✦✦
✦Before operating your new XTM Racing Mammoth ST
Nitro Stadium Truck, please read and understand the warnings listed on
the next page. Failure to do so could lead to bodily harm and/or injury.
The XTM Racing Mammoth ST Nitro Stadium Truck is not intended for
persons under 12 years of age, unless closely supervised by an adult.
INCLUDES HITEC AGGRESSOR RADIO AND POWERFUL XTM 24.7 ENGINE!

2
ENGINE WARNINGS
●Never use any fuel in your engine other than glow fuels
specifically designed for use in model car engines. Use of any
other types of fuel can cause severe damage to your engine and/or
personal injury. NEVER USE GASOLINE OR DIESEL FUEL!
●Never operate your model on any public streets. This could
cause traffic accidents, personal injury or property damage.
●Glow fuel engines emit exhaust vapors that are poisonous and
can be dangerous to your health. It is important that you operate
your engine in a very well-ventilated area, preferably outdoors.
●Before starting your engine, make sure that the throttle trim is
set to the idle position. Starting your engine at any setting above
idle can cause the model to lurch out of your hands.
●When your engine is running, there are certain parts that
rotate at high speeds. Be careful not to touch the drive shafts,
gears, clutch assembly or any other moving parts. Otherwise,
serious injury could result.
●It is normal for your engine and tuned pipe to get very hot
during operation. Never touch these parts while they are hot or
you could be burned.
●Model car engines produce vibration when they are running. It
is important to periodically check the engine mounting screws
and other assemblies to ensure they are tight. Running your
engine with the engine mounting screws loose can lead to
severe engine and/or chassis damage.
FUEL WARNINGS
●Glow fuels like those used in your model are poisonous.
Follow all the precautions that are printed on the fuel
manufacturer's container.
●Keep glow fuel out of the reach of children.
●Glow fuel is extremely flammable. Keep away from high heat,
sparks and flame.
GENERAL WARNINGS
●Under no circumstances should you operate your model in
crowds of people. Serious injury could result.
●Never operate your model on busy streets or if there are cars
around.
●Do not use your model to chase pets or other animals.
●The receiver and battery boxes are not waterproof; therefore,
do not drive through water, wet grass, mud or snow.
●Because your model is operated by radio control, it is important
to make sure you always are using fresh and/or fully charged
batteries. Never allow the batteries to run low or you could lose
control of the model.
●If your model becomes stuck, allow the engine to idle, then
retrieve your model by hand.
●To prevent excessive r.p.m.'s from damaging your engine and/or
drivetrain components, we suggest reducing throttle while in the
air during jumps.
FOR YOUR SAFETY - PLEASE READ THESE WARNINGS FIRST!
CUSTOMER SERVICE INFORMATION
If you should have trouble with any of the steps listed in these pages, or if you find a missing or damaged part in your kit, please contact
us at the address below:
Global Services
18480 Bandilier Circle
Fountain Valley, CA 92708
Phone: [phone] Fax: [phone] Email: [e-mail]
To allow us to serve your needs better, please include your email address with any correspondence you send to us. Your email address will be added to our Customer
Service Database so you will automatically receive free updates and tech notices for your particular product. You will also receive repair status updates (if applicable) and
other important information about your product as it becomes available.
IMPORTANT INFORMATION ABOUT YOUR EMAIL ADDRESS
Global Hobby Distributors will not disclose the information it collects to outside parties. Global Hobby Distributors does not sell, trade, or rent
your personal information to others . Your privacy is important to us.
CHECK IT OUT! We urge you to come check out our website at http://globalservices.globalhobby.com. There you will find public message boards
frequented by other XTM Racing product owners and the XTM Racing support staff. This is a great place to learn about new XTM Racing products,
get help and suggestions for your current XTM Racing products or just simply hang out and chat with people that share your same interests.
Check out our website for more information on
this and other exciting XTM Racing products!
http://xtm.globalhobby.com

3
INTRODUCTION
This booklet is designed to help you get your new Mammoth ST Nitro Stadium
Truck running as quickly as possible. This booklet includes information on
taking your Mammoth ST Nitro Stadium Truck from the box through its first
run. It also includes a chassis tuning section and a complete parts list with
detailed exploded view drawings. You will find good tips and recommendations
throughout this booklet, so keep it handy for future reference.
SOME POPULAR HOP-UPS FOR YOUR MAMMOTH ST NITRO STADIUM TRUCK
XTM Racing produces popular hop-ups for your Mammoth ST Nitro Stadium Truck. Please see page # 57 for a list of hop-ups, including
a reverse module kit. New hop-ups are always in the works, so check our website often.
http://xtm.globalhobby.com
Mammoth Size, Mammoth Performance. You’ll dominate Unlimited Monster Truck
Class with the Mammoth ST. This purpose-built truck, inspired by the
awesome performance and size of our original Mammoth, is a no-compromise,
no-holds-barred, hi-performance race truck. Look closely, you’ll see an
incredibly low CG, clean and easy-to-maintain chassis layout, a 2-speed
tranny, all-new diff housings, new multi-support upper arms, thick
low-profile shock towers, and increased suspension travel. The included
race wheels have 17mm hubs and fit the popular 40 series tires so you can
tune your truck to any track surface. XTM also features several tuning and
hop-up options so you can customize the truck to suit your needs and driving
style. From hard-anodized 5mm shock towers to an optional reverse module,
the ST will prove itself in every condition, from the backyard basher to
the unlimited monster truck racer. Mammoth Performance, Mammoth Size. The
Mammoth ST is the Ultimate Monster Truck Racer!

4
RECOMMENDED TOOLS AND SUPPLIES
This section lists the recommended tools and supplies that you need to purchase and have onhand to finish assembling and to run and
maintain your new Mammoth ST Nitro Stadium Truck. We have tested these items extensively with the Mammoth ST Nitro Stadium
Truck and found that they offer the best in reliability and value.
WHAT FUEL DO I USE?
Fuel can make a big difference in the way your engine performs. For the break-in period you should use a fuel specifically designed for
R/C car engines that contains no more than 20% nitromethane. Once the engine has been adequately broken in (about 45 minutes of
run-time) you can switch to an R/C car fuel containing up to, but no more than, 30% nitromethane.
✦✦
✦✦
✦WARNING✦✦
✦✦
✦We do not recommend using fuels designed for R/C airplane engine use. These fuels do not contain the proper
amount of lubricants; therefore, they will cause the engine to overheat and severe damage to the engine will result.
DO I NEED TO PURCHASE EXTRA GLOW PLUGS?
Yes. Even though your XTM Racing 24.7 comes with a glow plug already installed in the engine, glow plugs
wear out, especially during the break-in period; therefore, it's a good idea to have a couple of spares handy.
We recommend using a "medium" or "hot" heat-range glow plug intended specifically for performance
engines like the XTM Racing # 3 (P/N 146020 ) during the break-in process. After the break-in period you
may want to use a different heat-range glow plug. Use a colder glow plug like the XTM Racing # 4
(P/N 146021) if you're using 30% nitro fuel. Do not use glow plugs intended for four stroke airplane engines
or glow plugs with an "idle bar". Using the wrong type of glow plug will cause the engine to run erratically and make it difficult to tune
properly. The wrong type of glow plug could also damage the engine. AN XTM RACING # 3 GLOW PLUG IS INCLUDED IN THE ENGINE.
XTM Racing 20%
Nitro Car Fuel (P/N 145850)
Use For Break-In and For
Normal Use
USE THE FOLLOWING FUELS FOR THE BEST PERFORMANCE:
XTM Racing 20% Nitro Car Fuel - P/N 145850
(use this fuel for break-in and normal use)
XTM Racing 30% Nitro Car Fuel - P/N 145851
(use this fuel after break-in for more power)
DO I NEED TO USE A FUEL BOTTLE?
Yes. Because fuel is packaged in quarts or gallons, you will need to use a smaller
bottle with an extension wand to fill the fuel tank. Fueling using this method is much
easier and a lot less messy. The XTM Racing 500cc Fuel Bottle is a good choice.
XTM Racing Fuel Bottle
(P/N 145920)
Use This to Fill the Fuel Tank
HOW DO I REMOVE THE GLOW PLUG?
A long reach glow plug wrench is necessary to easily and quickly remove and replace
glow plugs. The XTM Racing 1/8th Scale 4-Way Wrench works great.
XTM Racing 1/8th
Scale 4-Way Wrench
(P/N 146036)
Use This to Remove and Reinstall
the Engine's Glow Plug
WHAT DO I USE TO IGNITE THE GLOW PLUG?
A glow starter is a battery-operated device that, when attached to the glow plug,
heats the glow plug so that the engine can start. The glow starter is then removed
after the engine is running. The XTM Racing Glow Starter with Meter is a perfect
choice. It comes complete with a battery, charger and a built-in meter to let you know
if your glow plug is good.
XTM Racing
Glow Starter
(P/N 146045)
Use This to Ignite the
Engine's Glow Plug
Continued On Next Page ☛☛
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5
RECOMMENDED TOOLS AND SUPPLIES, CONTINUED....
In addition to the items listed on the previous page, the following tools and supplies will also be required to run and maintain your
Mammoth ST Nitro Stadium Truck:
●Trinity "8 Pack" AA Alkaline batteries - P/N 837801
●Trinity "4 Pack" AA Alkaline batteries - P/N 837800
●Trinity "Final Solution" after-run oil - P/N 843744
●XTM Racing Air Filter Oil - P/N 149571
●Emerald Nitro Car Cleaner - P/N 340196
●Small, flat blade screwdriver
●# 2 Phillips head screwdriver and Assorted Metric Hex Wrenches
●Adjustable Open-End Wrench
●Assorted weights of silicone shock oil to tune the shocks and differentials (Optional)
Each radio system comes with a sticker on the back of the transmitter and on the receiver showing which frequency the radio system
operates on (either in the 27Mhz or 75Mhz band). No two radio systems can operate nearby each other if they are on the same
frequency. You can purchase transmitter and receiver crystals separately and change them if you plan on running your Mammoth ST
Nitro Stadium Truck with other people. We have provided a list of the frequencies that are available for your radio system.
BECOMING FAMILIAR WITH YOUR MAMMOTH ST NITRO STADIUM TRUCK
Antenna: Transmits the signal from the transmitter to the receiver. The antenna should be completely extended during use.
Battery Cover: This cover houses the 8 AA Alkaline batteries that power the transmitter.
Crystal: This is the frequency crystal of the transmitter. You can change crystals in both the transmitter and the receiver so that you and your friends
can drive at the same time. No two radio systems nearby can be operated on the same frequency.
On/Off Switch: Turns the transmitter on and off. Three L.E.D.s show the power status of the batteries.
Servo Reversing Switches: Allow you to quickly and easily change the direction the servos rotate by just flipping the switches on the top of
the transmitter. The switches are located under the removable plastic cover.
Steering Wheel: Controls your truck's steering. Turn the wheel to the right and the truck turns right. Turn the wheel to the left and the truck turns left.
Steering Dual Rate Control Dial: This dial adjusts the overall travel of the steering servo. Push the dial forward for maximum steering (125%). Pull
the dial back to reduce steering travel (minimum 60%).
Throttle/Brake Trigger: Controls the speed and braking ability of your truck. Pull the trigger to accelerate, release the trigger to decelerate, and
push the trigger to brake.
Trim Dials: These dials, one for steering and one for throttle/brake control, allow you to fine tune the servo's center by turning the dials on the
transmitter back and forth.
Continued On Next Page ☛☛
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☛
Channel # Frequency Part # (tx/rx)
67427xx/66427xx
01 16.995
02 27.045
03 27.095
04 27.145
05 27.195
06 27.255
61 75.410
90 75.990
Through 67475xx/66475xx
Note that "xx" is the actual channel number
you want to purchase.
27Mhz
75Mhz

6
BECOMING FAMILIAR WITH YOUR MAMMOTH ST NITRO STADIUM TRUCK, CONTINUED....
2-Speed Transmission: The 2-speed transmission automatically shifts from low to high gear for awesome top speed and features an adjustable
shift point. Tighten the adjustment screw to shift at a higher speed. Loosen the adjustment screw to shift at a lower speed.
Air Filter: The air filter is made of foam and prevents dirt and debris from entering the engine through the carburetor. The air filter should be "wet" with
air filter oil for maximum efficiency.
Battery Box: This is where the receiver battery is mounted. The battery box protects the batteries from dust, dirt and oil. The battery box is not
waterproof.
Body Mount: Made of high-impact nylon plastic for strength, the body mount secures the body into place.
Engine: The Mammoth ST Nitro Stadium Truck includes the powerful XTM Racing 24.7 engine with pull-starter and tuned pipe for ease of use and
great performance.
Front Bumper: Made out of high-impact nylon plastic, the front bumper protects the chassis from most head-on impacts.
Fuel Tank: The fuel tank holds the fuel that your engine uses. This fuel tank includes a fuel pressure nipple that connects to the tuned pipe to
pressurize the fuel system and also features a quick-flip type lid for fast refueling.
Pull-Start Handle: Used to start the engine in place of an electric starter.
Shock: Each shock is oil-filled and uses a spring that is well suited for most off-road conditions. The shocks feature threaded shock bodies that allow
the shocks to be easily tuned for different driving conditions. The shocks come standard with 100Wt oil and 1.5mm springs.
Steering Servo: This servo controls the vehicle's steering. A "servo saver" is used to help prevent the servo gears from being stripped out.
Steering Tie-Rod: The tie-rod connects the steering linkage and the castor block. The tie-rods are adjustable so you can make toe-angle
adjustments to the front wheels.
Tuned Pipe: The tuned pipe is an expansion muffler that greatly increases the power output of the engine.
Wheel/Tire Assembly: The Mammoth ST Nitro Stadium Truck includes molded rubber tires with a tread pattern that is good for most off-road
applications. The wheels are molded in one piece from lightweight, high-impact plastic for strength.
PHOTO SHOWN MAY DIFFER
FROM ACTUAL PRODUCTION MODEL

7
Now that you are familiar with the major component parts of your Mammoth ST Nitro Stadium Truck, and with the functions of the Hitec
Aggressor transmitter, it's time to prepare your Mammoth ST Stadium Truck for its first run.
✦✦
✦✦
✦IMPORTANT✦✦
✦✦
✦Before continuing, please double-check that you've read and understood the warnings printed on page # 2. It's
important that you understand this information before preparing to run your Mammoth ST Nitro Stadium Truck. Also, remember, if you
have any questions or encounter any problems, you can contact us using the Customer Service Information on page # 2.
YOUR MAMMOTH ST NITRO STADIUM TRUCK SHOULD INCLUDE THE FOLLOWING ITEMS SEPARATELY IN THE BOX:
●Mammoth ST Nitro Stadium Truck Chassis
●Hitec Aggressor AM Transmitter
●Telescoping Transmitter Antenna
●Body and Wing w/ Mounting Screws (2)
PREPARING TO RUN YOUR MAMMOTH ST NITRO STADIUM TRUCK
STEP 1: FINAL ASSEMBLY
❑Push the telescoping transmitter antenna down into the molded hole in the top of the
transmitter.
❑Thread the antenna (clockwise) into place and tighten it gently until it stops.
✦✦
✦✦
✦IMPORTANT✦✦
✦✦
✦Do not force the antenna into place or tighten it too strongly. Doing so
could cause damage to the antenna and/or transmitter.
❑Remove the plastic battery cover from the bottom of the transmitter.
❑Install 8 AA Alkaline batteries into the battery tray, double-checking to make sure that
the polarity is correct.
❑Reinstall the battery cover and set the transmitter aside for now.
●Tires and Wheels (Glued)
●Body Clips (4)
●Decal Set
●Yellow Plastic Parts Set
Upgrading your transmitter to use rechargeable NiCD cells is easy. All you
need to do is purchase 8 AA rechargeable NiCD cells (P/N 256911) and a
110V AC overnight charger (P/N 759805). This will allow you to recharge the
batteries without removing the batteries from the transmitter and it will save
you money in the long run, since you won't need to purchase Alkaline
batteries when they run low.
HITEC AGGRESSOR TRANSMITTER UPGRADE TIP
❑Install the tires and wheels onto the chassis, making sure to tighten the wheel retaining
nuts firmly.
☞Notice that the back of the wheels are molded to key over the hex-shaped wheel
hubs. All four wheels and tires are the same.
●Plastic Receiver Antenna Tube
●Toe-Angle Adjustment Blocks
Continued On Next Page ☛☛
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8
❑Install 4 AA Alkaline batteries into the battery holder, double-checking to make sure
that the polarity is correct.
✦✦
✦✦
✦IMPORTANT✦✦
✦✦
✦Make sure that the batteries are pushed firmly into place. They should
not be loose. If for any reason the plug from the battery holder (male red plug) is not
plugged into the switch (female red plug), plug them together now. The plugs can fit
together only one way.
If you would like to upgrade to a rechargeable NiMH battery pack, instead of using Alkaline dry cells, we
suggest using the XTM Racing 5 cell 1000mAH NiMH RX Battery Pack (P/N 145801). Not only is this battery
pack rechargeable, but because it's a 5-cell battery, it will operate the servos at a higher power
rating and faster speed. We also suggest upgrading the on/off switch to one that includes a
separate charge cord. The Cirrus On/Off Switch with Charge Cord (P/N 444733) works
well. This will allow you to charge the receiver battery without removing the battery
box cover. When installing the switch, make sure that you leave the charge cord
outside of the receiver box, but secured to the chassis, so it doesn't get damaged.
✦✦
✦✦
✦WARNING✦✦
✦✦
✦Never attempt to recharge non-rechargeable batteries. The batteries
could explode and cause serious injury.
MAMMOTH ST NITRO STADIUM TRUCK UPGRADE TIP
❑Remove the four screws from the receiver mounting box cover, then remove the cover.
❑Uncoil the receiver antenna and feed it out through the hole in the cover.
❑Reinstall the cover, making sure not to pinch any of the wires.
❑Open the battery box cover by removing the retaining clip and pulling up on the front of
the cover. The battery box cover is hinged at the back for convenience.
❑Remove the battery holder from the battery box.
❑Slide the receiver antenna into one end of the plastic antenna tube and out the
other end.
❑Push the end of the antenna tube firmly into the metal clamp in the top of the receiver
mounting box cover, then gently tighten the knurled nut to lock the tube into place.
✦✦
✦✦
✦IMPORTANT✦✦
✦✦
✦Leave the excess antenna hanging from the top of the tube. Under
no circumstances should you cut the antenna shorter.
Continued On Next Page ☛☛
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9
❑Slide the receiver's on/off switch to turn the receiver on. You should hear the servos
move to their proper positions.
STEP 2: RANGE CHECKING THE RADIO CONTROL SYSTEM
To ensure that the radio control system is operating properly and to prevent any chance of a runaway model, the radio control system
should be range checked before the first run of the day and/or after a crash. To range check the radio control system, do the following:
❑With the transmitter and receiver turned on, extend the transmitter antenna completely.
❑With the truck on the ground (without the engine running) walk away from it about 75 feet. Move the steering wheel while looking
at the truck's wheels. The wheels should pivot back and forth as you rotate the steering wheel back and forth. Because of the truck's
weight and large wheels, the steering won't operate perfectly smoothly unless you lift the front of the truck off the ground.
This goes away as soon as the truck starts rolling.
✦✦
✦✦
✦IMPORTANT✦✦
✦✦
✦If the radio system does not operate properly, please refer to the troubleshooting guide on page # 22 before
continuing further. Never attempt to operate your Mammoth ST Nitro Stadium Truck if the radio control system is not functioning properly.
MAMMOTH ST NITRO STADIUM TRUCK SAFETY TIP
Always turn on the transmitter first, followed by the receiver. After you're done, turn off
the receiver first, then turn off the transmitter. This will prevent the possibility of a
runaway model or damage to the servos.
STEP 3: DOUBLE-CHECK THE STEERING AND THROTTLE/BRAKE CONTROLS
✦✦
✦✦
✦PRO TIP✦✦
✦✦
✦We suggest doing the steering tests while lifting the front of the truck off the ground. This will allow the steering system
to operate smoothly, without any binding.
❑Slide the transmitter's on/off switch up to turn on the transmitter. The green LED should
glow brightly.
✦✦
✦✦
✦IMPORTANT✦✦
✦✦
✦If the green LED does not glow or if the red LED is glowing, check the
batteries in the transmitter and replace them if necessary.
❑With the transmitter and the receiver turned on, rotate the
transmitter's wheel forward (to the right). The truck's front wheels
should turn right.
✦✦
✦✦
✦IMPORTANT✦✦
✦✦
✦If the wheels don't turn right, flip the steering
servo reversing switch on the top of the transmitter to change the
direction that the front wheels turn. Refer to the transmitter photo
and definitions on page # 5 if you don't remember how to use the
servo reversing switches.
Continued On Next Page ☛☛
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10
❑Rotate the transmitter's wheel backward (to the left). The
truck's front wheels should turn left.
❑Let go of the transmitter wheel. The truck's wheels should return
to center.
✦✦
✦✦
✦IMPORTANT✦✦
✦✦
✦If the wheels do not point straight ahead (center)
after you return the transmitter wheel to center, turn the steering
trim dial on the transmitter to adjust the wheels so that they point
straight ahead. Refer to the transmitter photo and definitions on
page # 5 if you don't remember how to use the servo trim dial.
❑Carefully pull the air filter assembly off of the carburetor, so that
you can see the carburetor barrel.
❑Pull back on the throttle trigger. The carburetor barrel should open
completely and the brakes should be disengaged (i.e., the truck
should roll forward smoothly).
❑Let go of the throttle trigger and the carburetor barrel should return
to its idle position - open about 1/16" (1mm). The brakes should still be
disengaged, too. If not see page # 17 "Adjusting the Brake Linkage".
✦✦
✦✦
✦IMPORTANT✦✦
✦✦
✦If the carburetor barrel does not open when you
pull back on the throttle trigger, flip the throttle servo reversing switch
on the top of the transmitter to change the direction.
✦✦
✦✦
✦PRO TIP✦✦
✦✦
✦If the carburetor barrel does not open completely, turn the throttle trim dial on the transmitter until the carburetor barrel
opens completely when you pull back fully on the throttle trigger.
❑Push the throttle trigger forward. The carburetor barrel should
stay in the idle position (open about 1/16" (1mm)) and the brake
linkage should move forward and engage the brakes (i.e., the truck
will not be able to roll at all).
❑Let go of the throttle trigger and the brakes should disengage.
✦✦
✦✦
✦IMPORTANT✦✦
✦✦
✦If you need to adjust the brake linkage, see
page # 17 "Adjusting the Brake Linkage".
AIR FILTER WARNING
Under no circumstances should you operate the engine without the air filter installed on the carburetor. The air filter prevents dust and
debris from entering the engine and damaging it. If you operate your engine at any time without the air filter installed, the engine will
not be covered under warranty should it need repair.
❑Turn off the transmitter and receiver and push the air filter back onto the carburetor. If it's difficult to push the air filter back onto
the carburetor, apply a thin coat of after-run oil to the inside of the silicon boot before reinstalling it.
Continued On Next Page ☛☛
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11
STEP 4: WETTING THE AIR FILTER
To prevent damage to your engine, we strongly recommend "wetting" the air filter element, using a high-quality filter oil or after-run oil.
If you will be running your truck in extremely dusty
conditions, we suggest using a prefilter sleeve over
the air filter. Wet the main filter element as described
below, then simply slide the prefilter sleeve over
the main filter. It's not necessary, nor desirable,
to wet the prefilter sleeve. We suggest using XTM
Racing 1/8th Scale Prefilter Sleeves (P/N 149412).
MAMMOTH ST NITRO STADIUM TRUCK UPGRADE TIP
❑To wet the air filter element, simply squeeze an ample amount of air filter oil or after-run oil onto the filter element and work it through
the filter element, using your fingers. Use enough oil to completely saturate the filter element. The entire filter element should be oiled,
but not so much that excess oil is dripping from it.
BECOMING FAMILIAR WITH THE XTM RACING 24.7 NITRO ENGINE
Refer to the photo at left to familiarize yourself with your engine's
carburetor. All of the carburetor settings come preset from the factory
for initial starting and break-in, but you should have a small flat blade
screwdriver handy to make adjustments to the carburetor during the
break-in process, which will be detailed in the next section.
WARNING!! PLEASE READ THIS INFORMATION BEFORE PROCEEDING!!
Your Mammoth ST Nitro Stadium Truck comes equipped with the user-friendly and powerful XTM Racing 24.7 nitro engine. Before
starting the engine for the first time, you MUST read this section very carefully. This section details the different parts of the engine's
carburetor and how to adjust the carburetor's needle valves to tune the engine. Failure to read this information may result in your
not knowing how to properly operate your new engine. Not knowing how to operate your new engine can result in damage
to the engine.
Continued On Next Page ☛☛
☛☛
☛
MAMMOTH ST NITRO STADIUM TRUCK UPGRADE TIP
To prevent your truck from going out of control should the radio control system encounter signal
loss, we suggest using an electronic failsafe. The failsafe is connected between the throttle/brake
servo and the receiver. The failsafe is designed to electronically bring the throttle to idle and apply
a preset amount of braking force should the radio control system lose its signal. We suggest using
the XTM Racing Micro-Electronic Failsafe (P/N 146077).
IT'S NOW TIME TO BECOME FAMILIAR WITH YOUR ENGINE. THIS INCLUDES HOW TO
SET THE CARBURETOR, BREAK IN THE ENGINE AND HOW TO TUNE IT PROPERLY.
PLEASE READ THE NEXT FEW PAGES VERY CAREFULLY.

12
LOW SPEED NEEDLE VALVE:
The low speed needle valve is preset from the factory for the initial starting procedure. Do
not make adjustments to it at this time. The low speed needle valve meters the air/fuel
mixture at idle and during transition from idle to full throttle. Turn the low speed needle
valve clockwise to lean the mixture. Turn the low speed needle valve counterclockwise to
richen the mixture. The low speed needle valve is preset from the factory, but minor
adjustments may need to be made to suit your application: fuel used, glow plug and
environment all contribute to the setting. Do not adjust the low speed needle valve
until AFTER the engine has been broken in.
If you need to reset the low speed needle valve to the factory setting, follow these simple procedures:
●Open the carburetor barrel completely.
●While holding the carburetor barrel open with your fingers, use a flat blade screwdriver to turn the low speed needle valve clockwise
until it stops. From this point, turn the low speed needle valve counterclockwise 3 full turns. This is the factory setting.
IMPORTANT TIP ABOUT RESETTING THE LOW SPEED NEEDLE VALVE
IDLE STOP SCREW:
The idle stop screw adjusts the closure of the carburetor barrel. We recommend that the
idle stop screw be adjusted so that the carburetor barrel stays open about 1/16" (1mm).
Turning the screw clockwise will cause the barrel to stay open more. Turning the
screw counterclockwise will allow the barrel to close more. If the carburetor barrel stays
open too far, the engine will idle very high and the clutch will never disengage. This will
damage the clutch very quickly. If the idle stop screw is closed too far, the engine may die
during idle. Ideally, the engine should idle smoothly, yet slow enough so that the
clutch stays disengaged.
HIGH SPEED NEEDLE VALVE:
The high speed needle valve is preset from the factory for the initial starting procedure.
Do not make adjustments to it at this time. The high speed needle valve is used to
meter the air/fuel mixture at full throttle. Turn the needle valve clockwise to lean the
mixture or turn the needle valve counterclockwise to richen the mixture.
The factory setting for the high speed needle valve is 3 full turns out from bottom.
FUELING AND STARTING THE XTM RACING 24.7 NITRO ENGINE
If at any time the pull-starter becomes very tight or difficult to pull - STOP! The engine has become flooded and the excess fuel
must be removed from the engine or damage to the pull-starter and/or engine could occur. To remove the excess fuel from the
engine follow the procedures listed below:
●Completely close the high speed needle valve until it bottoms out. Do this gently. Don't force it!
●Remove the glow plug from the cylinder head.
●With a rag over the top of the engine, pull the pull-starter cord several times to expel the excess fuel from the engine.
●Check to make sure that the glow plug has not been fouled, then reinstall it.
●Reset the high speed needle valve 3 full turns out from bottom.
WARNING!! PLEASE READ THIS BEFORE STARTING YOUR ENGINE FOR THE FIRST TIME!!
✦✦
✦✦
✦WARNING✦✦
✦✦
✦Under no circumstances should you operate the engine without the air filter installed on the carburetor. The air filter
prevents dust and debris from entering the engine and damaging it. If you operate your engine at any time without the air filter installed,
the engine will not be covered under warranty should it need repair. Also make sure that you "wet" the air filter as described on page # 11.
Continued On Next Page ☛☛
☛☛
☛

13
❑Lift the fuel tank lid and carefully fill the fuel tank until the fuel level is just below the top
of the fuel tank.
✦✦
✦✦
✦WARNING✦✦
✦✦
✦Use fuel that is appropriate for nitro car and buggy engines. Do not use
gasoline or diesel fuel! For the break-in period you should use fuel specifically
designed for R/C car engines that contains no more than 20% nitromethane
❑Using your glow plug wrench, verify that the glow plug is installed in the cylinder head and tight. If it's not already preinstalled, install
it, using one copper gasket.
❑Prime the engine by first opening the throttle completely and covering the exhaust
opening in the tuned pipe with your finger, then pull the pull-starter cord several times
until you see fuel just start to enter the carburetor through the fuel line.
✦✦
✦✦
✦IMPORTANT✦✦
✦✦
✦Do not pull the pull-starter cord all the way out or damage to the
pull-starter will occur. Use a couple of short pulls - about 7 or 8 inches long.
❑Remove your finger from the tuned pipe opening and close the throttle down to the
idle position.
❑While holding the truck firmly with one hand , carefully pull on the pull-starter cord
3 times, using short, quick pulls.
✦✦
✦✦
✦IMPORTANT✦✦
✦✦
✦If you can't turn the engine over using the pull-starter, don't force it.
The engine is probably flooded. See the warning and resolution on page # 12.
IMPORTANT TIP ABOUT GLOW PLUGS
An XTM Racing # 3 Hot Heat-Range glow plug is included with your engine. We suggest having a couple of extra glow plugs handy,
because it can be expected that glow plugs will wear out quickly during the engine's break-in process. This glow plug will suit most
users during the break-in process. You may or may not need to change to a different type of glow plug after break-in is complete.
There are a variety of different heat range glow plugs to suit your engine.
Typically, use a hotter glow plug if you're using 15% - 20% nitro fuel or are
running in cooler ambient temperatures. Hotter glow plugs typically
improve idle and transition, too. Use a cooler glow plug if you're running
25% - 30% nitro fuel or are running in higher ambient temperatures. See tip on page # 16 about running 30% nitro fuel.
(P/N 146021) XTM Racing # 4 Glow Plug - Medium
(P/N 147025) SH Engines # 5 Glow Plug - Cool
❑Connect a fully charged glow starter to the top of the glow plug, making sure that the
glow starter is locked firmly onto the top of the glow plug. You don't want it to fall off while
you're trying to start the engine.
When the engine is new, it can sometimes be difficult to turn over using the pull-starter.
You may find you need to pull the pull-starter harder than you expect. A trick to help this
is to loosen the glow plug slightly, start the engine, then remove the glow starter and
retighten the glow plug. This effectively lessens the engine's compression, making it
easier to turn over with the pull-starter.
NEW ENGINE STARTING TIP
Continued On Next Page ☛☛
☛☛
☛

14
❑With the throttle still in the idle position, hold the truck firmly with one hand and
carefully pull on the pull-starter cord, using short, quick pulls, until the engine starts.
❑After the engine starts, release the pull-starter cord, allow the engine to run for about
10 seconds, then remove the glow starter from the glow plug.
✦✦
✦✦
✦IMPORTANT✦✦
✦✦
✦If the engine does not start after a dozen pulls, refer to the
troubleshooting guide on page # 22.
❑Once the engine is running, to stop the engine, carefully pinch the fuel line with your
fingers until the engine stops. Make sure to pinch the fuel pick-up line and not the fuel
pressure line. The fuel pick-up line is the one connected to the carburetor.
✦✦
✦✦
✦PRO TIP✦✦
✦✦
✦When you pinch the fuel line to stop the engine, you must pinch it hard
and hold it. The engine will rev up quickly, then die. We suggest holding the truck while
doing this, so that it doesn't lurch out of your hands.
✦✦
✦✦
✦WARNING✦✦
✦✦
✦Be careful not to touch any parts of the engine or the tuned pipe because
they will be hot.
Until you're actually ready to break in the engine, do not run the engine for more than a few minutes. If you run the engine longer
without breaking in the engine properly, damage to the engine can occur. Break-in will be done in the next section.
WARNING ABOUT RUNNING YOUR ENGINE FOR THE FIRST TIME
BREAKING IN THE XTM RACING 24.7 NITRO ENGINE
The XTM Racing 24.7 engine is an ABC engine. The cylinder sleeve is tapered at the top, causing severe resistance when the piston
moves through the top of the stroke. This is normal. When the engine heats up to operating temperature, this resistance will
decrease and the proper clearance will be achieved. The break-in procedure will guide you through the steps necessary to properly
break in your new engine. Please follow the steps closely.
FUEL RECOMMENDATION:
Fuel can make a big difference in the way your engine performs. For the
break-in period you should use a fuel specifically designed for R/C car engines
that contains no more than 20% nitromethane. Once the engine has been
adequately broken in (about 45 minutes of run-time) you can switch to an R/C car
fuel containing up to, but no more than, 30% nitromethane.
✦✦
✦✦
✦WARNING✦✦
✦✦
✦We do not recommend using fuels designed for R/C airplane
engine use. These fuels do not contain the proper amount of lubricants;
therefore, they will cause the engine to overheat or run erratically and severe
damage to the engine can result.
ENGINE BREAK-IN TIP
To make sure that you're not
leaning out the engine too
much and overheating it
during the break-in process,
we suggest using a temp gun
to monitor the engine's
temperature.
During break-in, the engine
should not surpass 230º.
GLOW PLUG RECOMMENDATION:
The glow plug can make a big difference in how your engine performs. We recommend using a "medium" or "hot" heat-range glow plug
intended specifically for performance engines like the XTM Racing # 3 (P/N 146020 ) during the break-in process. After the break-in
period you may want to use a different heat-range glow plug. Use a colder glow plug like the XTM Racing # 4 (P/N 146021) if you're
using 30% nitro fuel. Do not use glow plugs intended for four stroke airplane engines or glow plugs with an "idle bar". Using the wrong
type of glow plug will cause the engine to run erratically and make it difficult to tune properly. The wrong type of glow plug could also
damage the engine.
AIR FILTER:
The air filter is a very important part of your engine. Failure to use the air filter will damage the engine in a very short period of time.
Make sure that you "wet" the air filter as described on page # 11 and use a prefilter sleeve if you are driving in dusty conditions.
Continued On Next Page ☛☛
☛☛
☛

15
If, during the break-in process, the pull-starter assembly slips when you try to start
the engine, the one-way bearing and pull-starter shaft may be coated with excess
fuel oil. This can occur because the excess oil in the engine during the break-in
process gets into the one-way bearing. To fix this, carefully remove the one-way
bearing and the pull-starter shaft, clean them with rubbing alcohol and reassemble
the parts. Use the engine exploded parts view to see how the parts are assembled.
Also, be careful when removing the pull-starter assembly to ensure that the recoil spring
does not uncoil and fly out.
ENGINE BREAK-IN TIP: "WHY IS MY PULL-STARTER SLIPPING?"
STEP 1: BREAKING IN THE ENGINE
✦✦
✦✦
✦WARNING✦✦
✦✦
✦Do not adjust the low speed needle valve until after the engine has been broken in. You can begin to adjust the low
speed needle valve after you have broken in the engine and after you have read and understood Step 2: Fine Tuning the Engine below.
The high speed needle valve is preset from the factory for easy starting in most conditions for the break-in period.
❑Follow the previous procedures to fill the fuel tank and start the engine.
❑Once the engine starts, keep the glow starter attached to the glow plug and
let the engine run for about 10 seconds without giving it throttle. This will allow
the engine to warm up. At this point the engine should be running very "rich" and
the engine will also sound like it's running rough.
❑After the engine has been running for about 10 seconds, remove the glow
starter from the glow plug. Advance the throttle in short, quick bursts and drive
the truck for about 2-3
minutes. If the engine is
running rich enough, you should notice smoke coming from the tuned pipe
and the engine should sound like it’s running very rough. Also, the truck will
barely be moving because the engine is running so rich that it won't produce
much power. This is
what you want for now. If there is not smoke coming from the tuned pipe,
richen the high speed needle valve 1/4 turn. After 2-3 minutes stop the engine by
pinching the fuel line to the carburetor.
❑Let the engine cool for approximately 10 minutes, then restart it. Set the high speed needle valve mixture to a slightly leaner setting,
about 1/8 turn more in. Repeat the procedure above, then stop the engine and let it cool for approximately 10 minutes.
❑Repeat the procedure above, leaning the high speed needle valve slightly more each time. In all, you should run the engine a total
of about 45 minutes. After 45 minutes of run-time the engine will be broken in. Run the engine with the high speed needle valve set
slightly rich, but lean enough to power the truck adequately. At this point the engine should hold a good setting on the high speed
needle valve and you can begin to fine tune the needle valve settings to increase performance.
✦✦
✦✦
✦IMPORTANT✦✦
✦✦
✦It is of the utmost importance that the engine never be leaned out too much. When running the engine, you
should always be able to see a slight trail of smoke coming from the tuned pipe. If you can’t, stop the engine immediately and
richen the high speed needle valve. You should also make sure there is plenty of air flowing over the cylinder head to keep the
engine from overheating.
ENGINE TUNING TIP
No two engines will have the exact same needle
valve settings once broken in. Different fuels used,
different types and heat-ranges of glow plugs, the
outside air temperature and air pressure all affect
the engine. The factory needle valve settings on
page # 12 are break-in settings. If you reset the
needle valves to the factory settings, the engine
will run very rich and you will need to retune the engine.
ENGINE BREAK-IN TIP
Break in the engine without the body installed. It's
important that the engine have adequate airflow
during the break-in process.
ENGINE BREAK-IN TIP
During break-in, it's normal for excessive fuel oil
and exhaust residue to drip from the tuned pipe.
After your engine has been broken in, you can set the high and low speed needle valves for optimum engine performance.
STEP 2: FINE TUNING THE ENGINE
Continued On Next Page ☛☛
☛☛
☛
Be careful to never lean out the engine too much. Remember that the lubricants for your engine are suspended in the fuel. If you lean
out the fuel mixture too much you will also be lowering the amount of lubricant entering your engine. Less lubricant means more
chance of your engine overheating and possible engine failure.
WARNING ABOUT TUNING YOUR ENGINE

16
SETTING THE HIGH SPEED NEEDLE VALVE:
❑Start the engine and remove the glow starter from the glow plug, then allow the engine to warm up for about 10 seconds.
❑After the engine has warmed up, drive the truck as you normally would. If the engine seems to be running rich (i.e., not reaching
maximum power), lean the high speed needle valve about 1/16 of a turn at a time until the desired setting is achieved. Always make
sure that you run the engine slightly rich - you want to be able to see a faint exhaust trail at all times.
SETTING THE LOW SPEED NEEDLE VALVE:
❑Start the engine and lean out the high speed needle valve as per the procedures above. Close the throttle until the engine slows
down enough so that the clutch is disengaged and the wheels don’t turn when the truck is lifted from the ground. Allow the engine to idle
for about 10-15 seconds.
❑While holding the truck off the ground (making
sure to keep your fingers out of the moving parts),
quickly open the throttle in a short burst. If the
engine just stops running as soon as the throttle is
advanced, the low speed needle valve is too lean
and the engine is not getting enough fuel. With the
engine stopped, richen the low speed needle valve
about 1/16 of a turn (counterclockwise).
❑Restart the engine and repeat the procedure above until the engine will transition smoothly and quickly. Very slight hesitation in the
transition is normal.
❑If you quickly advance the throttle and the engine seems to be very rich during transition (i.e., lots of smoke coming from the tuned
pipe and very rough sounding), the low speed needle valve is too rich and the engine is getting too much fuel. With the engine stopped,
lean the low speed needle valve about 1/16 of a turn (clockwise).
❑Restart the engine and repeat the procedure above until the engine will transition smoothly and quickly. Very slight hesitation in the
transition is normal.
❑Now drive the truck as you normally would for a while to get a feel for how the engine reacts to throttle. Now that you know the proper
way to tune the engine, you can make slight adjustments to the carburetor until you are satisfied with the performance.
To keep your engine operating at peak performance there are some basic maintenance procedures that need to be performed on the
engine on a regular basis:
●After you are finished running the engine for the day, pinch the fuel line to stop the engine. This will allow the engine to burn any excess
fuel out of the crankcase.
●Remove the air filter element and wash it thoroughly in warm water and a small amount of liquid detergent. After it's clean, allow it to
dry, then reoil it and install it back into the air filter housing.
●Remove the glow plug from the engine and squirt several drops of high-quality after-run oil into the glow plug hole. Pull the pull-start cord
several times to distribute the oil throughout the engine, then reinstall the glow plug. The after-run oil will prevent the inside of the engine
(especially the crankshaft bearings) from rusting.
KEEP IT SMOOTH
Loop four nylon ZIP ties around the
corners of the engine's cylinder head,
making sure that the ratchet portion of
the ties are up toward you. When your
truck flips over, the ties will prevent the
cylinder head from being scratched
and gouged.
BASIC ENGINE MAINTENANCE
●Clean the outside of the engine using a heavy brush and nitro
car cleaner, then dry the engine, using a rag or compressed air.
●Periodically check the condition of the clutch to check for wear.
●Periodically oil the clutch bell bearings.
●Check the engine's cylinder head bolts and backplate screws
after each day of use to ensure that they're tight. This will
prevent air leaks from causing erratic engine performance.
To get more power from your engine you can use fuels containing
up to 30% nitromethane. We must caution you, though, that
once you run the engine with increased nitro you may not get
satisfactory results if you decide to go back to a lower nitro
content. Also, if you use fuels containing 30% nitro, we
suggest adding a .10mm head gasket (# 148418) to lower the
compression ratio. If you don’t lower the compression ratio, overheating and
erratic running will likely occur.
PLEASE READ IF YOU'RE USING 30% NITRO FUEL

17
INSTALLING THE BODY
❑Carefully peel the protective layer from off the top of the body and the wing.
✦✦
✦✦
✦IMPORTANT✦✦
✦✦
✦The body is covered by a thin plastic protective layer at the factory
that prevents damage to the body during assembly and shipping. This protective layer
must be removed before you apply the decals.
❑Remove the decals from their protective backing and adhere them onto the body.
❑Attach the wing to the body, using the two self-tapping screws provided.
❑Install the body onto the chassis, using the body clips provided to hold it in place.
❑Double-check that the body does not
interfere with the wheels, the suspension or
the tuned pipe. If it does, you will need to
trim the body slightly to fit around those areas.
✦✦
✦✦
✦PRO TIP✦✦
✦✦
✦Other than during the break-
in period, always make sure that you
install the body when driving your truck.
If your truck flips over, the body will help
protect the chassis and its components.
TUNING GUIDE - MAKING CHASSIS ADJUSTMENTS
Chassis alignment and geometry are important if you want your truck to perform well. A good performing truck means a truck that is
easier to drive, too. Follow our guidelines in this section to get the most out of your Mammoth ST Nitro Stadium Truck.
✦✦
✦✦
✦IMPORTANT✦✦
✦✦
✦It's very important when making changes to the settings of your truck that you make the settings the same for each
side. For example, if you change the spring tension on the right front shock, you should change the spring tension on the left front
shock the same amount, etc.
Do not make any changes that are more than 3 degrees from the initial settings listed or the handling characteristics of your truck will
become very poor.
Continued On Next Page ☛☛
☛☛
☛
The brake linkage on your truck is preset from the factory; however, after running the truck for a while you may find that the brake linkage
needs adjusting. Follow the information below to check and adjust the brake linkage:
With the transmitter and receiver turned on, and the throttle/brake trim lever centered,
the truck should roll forward smoothly (i.e., the brakes should be disengaged). If the
brakes are dragging when the throttle trigger is at neutral, the brake discs will wear out
very quickly. To ensure that the brakes are disengaged, always make sure that there is
a 1/16" wide gap between the two rear steel adjustment collars and the brake levers.
Both steel adjustment collars should be adjusted so that they are equal distance behind
each of the two brake levers. This will ensure that both brake levers engage equally
during braking.
●To make adjustments to the brake linkage, simply loosen the grub screw in the
adjustment collars behind the brake levers and reposition them, then retighten the
grub screws. Moving the collars forward, toward the brake levers, will result in the
brakes coming on sooner and more forcefully.
ADJUSTING THE BRAKE LINKAGE

18
ADJUSTING THE TOE ANGLE
The toe angle is the angle of both front tires (or rear tires) to each other, when viewed from above. Toe-in is when the front of both tires
point toward each other and toe-out is when the front of both tires point away from each other.
●For the front tires, toe-in will make your truck track straighter, but the steering will be more sensitive. Toe-out will desensitize the
steering, making the truck a little more driver-friendly.
●For the rear tires, if you're running on a smooth surface, we suggest no toe-in. If you are running on a rough surface, we suggest about
1 - 2 degrees of toe-in. This will give the rear end a little more "bite."
RECOMMENDED INITIAL SETTINGS:
●0 degrees toe-in on the front and rear for overall best 4WD driveability on most surfaces.
☞Adding more than 3 degrees of toe-in or toe-out will result in excessive loss of speed
and erratic handling.
✦✦
✦✦
✦IMPORTANT✦✦
✦✦
✦For more precise toe-in adjustments, use the R.P.M. Toe-in Gauge
part # 708049.
●To change the rear toe angle block, first remove the two screws from the bottom of the
chassis that hold the toe angle block screw guard in place, the remove the screw guard
from the chassis.
●Next, remove the two screws that hold the toe angle block in place, then carefully pull
out the toe angle block, being careful not to pull out the hinge pins.
●Install the desired toe angle block. Installation is the reverse of the disassembly
procedure.
To adjust the toe-angle of the front tires, turn the tie-rods (steel rods connecting each wheel to the steering arm) in or out with an
adjustable wrench. To adjust the toe angle of the rear tires, you need to replace the toe angle block, described below:
To adjust the toe-in on the rear tires, use one of the different composite toe angle blocks provided in your kit to set the desired toe angle.
For convenience, the degree of toe angle in each block is molded into the back of the blocks. The stock toe-angle block is 2º.
Camber is referred to as the amount of the tire's surface that contacts the ground. Tires that are exactly perpendicular to ground have
0 degrees of camber. If the top of the tire leans in toward the chassis, the tire has negative camber. If the top of the tire leans out away
from the chassis, the tire has positive camber.
RECOMMENDED INITIAL CAMBER SETTINGS:
●For driving on smooth surfaces set both the front and back wheels at 0 degrees.
●For driving on rough surfaces set the front wheels at -1 degree and the back wheels at -2 degrees.
ADJUSTING THE CAMBER ANGLE
Adjust the camber angle of the wheels by turning the upper turnbuckles in or out using an adjustable wrench.
☞Camber settings should be measured
with the vehicle at its normal ride height.
✦✦
✦✦
✦IMPORTANT✦✦
✦✦
✦For more precise
camber adjustments, use the R.P.M.
Precision Camber Gauge part # 708099.
Continued On Next Page ☛☛
☛☛
☛

19
✦✦
✦✦
✦IMPORTANT✦✦
✦✦
✦There are two screws in the 2-speed clutch housing. One is a grub screw that uses a 1.5mm hex wrench and the
other is a steel socket-cap screw that uses a 2.5mm hex wrench. Do not attempt to adjust the larger screw. This screw holds the
clutch housing onto the transmission shaft.
✦✦
✦✦
✦WARNING✦✦
✦✦
✦We suggest making 1/8th of a turn adjustments at a time, testing the shift point between each adjustment you make,
until you are satisfied with the transmission shift point.
The transmission shift point has been preset for you from the factory, but it is possible to fine tune the adjustment to suit your driving
style. The shift point is the point at which the 2-speed transmission will shift from first gear to second gear.
●Adjust the shift point by turning the small grub screw in the aluminum 2-speed clutch housing, using a 1.5mm hex wrench. Turning the
grub screw clockwise will make the transmission shift at a higher speed. Turning the grub screw counterclockwise will make the
transmission shift at a lower speed.
RECOMMENDED INITIAL SETTINGS:
●The 2-Speed transmission has been preset for you from the factory. No initial adjustments are necessary.
ADJUSTING THE 2-SPEED TRANSMISSION SHIFT POINT
To adjust the 2-speed transmission, you must first locate the small grub screw in the clutch
housing. To locate the grub screw, lift the truck off the ground and slowly rotate the spur
gear assembly until you can see the small grub screw through the milled access hole in
the clutch housing. Once the small grub screw is visible, use a 1.5mm hex wrench to
adjust the grub screw.
To make the transmission shift at a higher speed, turn the grub screw clockwise 1/8th of a
turn. To make the transmission shift at a lower speed, turn the grub screw counterclockwise
1/8th of a turn.
If you need to reset the 2-speed transmission shift point to the factory setting, follow these simple procedures:
●Carefully turn the grub screw (using a 1.5mm hex wrench) clockwise until it bottoms out, then turn the grub screw counterclockwise
9-1/2 turns (9 full turns plus 1/2 of a turn).
RESETTING THE 2-SPEED TRANSMISSION SHIFT POINT
By adjusting the spring tension of the shocks, you can increase steering sensitivity, adjust the ride-height of the truck and fine-tune the
dampening quality of the suspension system. How you drive your truck will dictate what settings you should be using. As an example,
if you're driving your truck off-road and going over lots of jumps, you may want to increase the spring tension of the front shocks to help
prevent the front of the truck from bottoming out. If you're racing your truck, local track conditions will dictate the settings to use.
RECOMMENDED INITIAL SETTINGS:
●We recommend initially leaving the adjustment rings in the factory locations.
ADJUSTING SHOCK SPRING TENSION
Increase or decrease spring tension by threading the adjustment ring up or down the
shock body.
Threading the ring down increases spring tension and the truck's ride height, and will
stiffen the overall dampening characteristics of the suspension. Threading the ring up
decreases spring tension and makes the dampening characteristics of the suspension
softer.
☞When adjusting the spring tension, make sure to adjust the right and left sides equally.
Continued On Next Page ☛☛
☛☛
☛

20
ADJUSTING SHOCK DAMPENING AND REPLACEMENT SHOCK SPRINGS
Changing the shock oil (the oil inside the shocks) will change the dampening characteristics
of the shocks. Typically, if you are running on smooth surfaces, use a heavier weight oil.
If you are running on rough surfaces, use a lighter weight oil.
✦✦
✦✦
✦IMPORTANT✦✦
✦✦
✦We recommend using only 100% Silicone Shock Oil. Do not use
motor oil. The shock oil used in the Mammoth ST Nitro Stadium Truck is 100Wt shock
oil. This is good for all-around use. For racing, you may want to consider using
45Wt oil.
Shock springs are easy to change and can make a difference in the way your truck handles relative to the type of terrain you're driving
on. If you drive your truck off-road, in a smooth, high-traction area, use stiffer springs to reduce body roll and weight shift. If the area
where you drive your truck is very bumpy, you might consider using softer springs to help absorb the bumps. If the area is bumpy and
you use harder springs, the truck will have a tendency to jump and hop around. The shock springs included with the Mammoth ST Nitro
Stadium Truck are suitable for most general off-road applications, but experimentation with different shock springs may be necessary to
find a setup that suits your particular driving style and location.
SUGGESTED AVAILABLE SHOCK SPRING UPGRADES
149372 1.3mm Shock Spring (RED)
149370 1.4mm Shock Spring (BLUE)
149366 1.5mm Shock Spring (WHITE) - STOCK
149363 1.6mm Shock Spring (YELLOW)
149364 1.7mm Shock Spring (BLACK)
The Mammoth ST Nitro Stadium Truck features front and rear gear differentials that each feature o-ring seals and cup-style housings. Both
differentials are packed with differential grease that is good for most driving conditions.
You can make fine-tuned adjustments to each differential by removing the differentials from the chassis, opening them up and replacing
the grease already inside the differentials with silicone differential oil.
●Adding heavier silicone oil will tighten the differentials and adding lighter silicone oil will loosen the differentials. If your truck feels
loose during turns, you can tighten the front differential or loosen the rear differential. If your truck is pushing during turns, you can
loosen the front differential or tighten the rear differential. We recommend using silicone oil weights between 30,000 (30K) and 100,000
(100K). For your convenience, we show you how to remove and disassemble the front differential. Removing and disassembling the
rear differential is similar. Refer to the parts blow up and assembly sequence on page # 25 if necessary.
ADJUSTING THE FRONT AND REAR DIFFERENTIALS
FRONT and REAR
SOFT
STIFF
●Remove the six screws from the bottom of the chassis that
hold the front bumper
in place, then remove
the front bumper.
●Next, remove the
screws that hold the
upper and lower hinge
pin support plates in
place, then remove
the two hinge pin
support plates.
●Pull the front half of the diff case straight out, then remove the
lower hinge pins and drop the suspension arms.
●Firmly pull the differential assembly straight out.
●Remove the two CVD drive shaft cups from the diff assembly,
then remove the four
screws that hold the
diff halves together.
●Pull the diff halves
apart, then pull the diff
assembly (w/ring gear
attached) out of the
diff housing.
●Remove the four
screws that hold the
diff case together,
then pull the diff case apart to open up the diff. You can now
remove the grease inside the diff and refill the diff with the
differential oil of your choice. Installation is the reverse of the
disassembly procedure.