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Tra4910 Manual

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Tra4910 Manual
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  • Traxxas CorporationCorporate Headquarters1100 Klein RoadPlano, Texas 75074Phone: 972-265-8000Toll-free 1-888-TRAXXAS

    Traxxas U.K.P.O. Box 1128Winterbourne, Bristol BS17-2SHEnglandPhone: 44-117-956-1002

    Internetwww.Traxxas.comE-mail: [email protected]

    Entire contents 2003 Traxxas Corporation. Traxxas, T-Maxx, TRX2.5, TQ-3, Top Fuel, EZ-Start, and ProGraphix are trademarks orregistered trademarks of Traxxas Corporation. Other brandnames and marks are the property of their respective holdersand are used only for purposes of identification. No part of thismanual may be reproduced or distributed in print or electronicmedia without the express written permission of Traxxas.

    030409

    2

  • Introduction

    Thank you for purchasing a Traxxas T-Maxx Nitro Monster Truck.Traxxas engineers have loaded your T-Maxx with innovativefeatures and incredible drive-over-anything performance thatyou wont find anywhere else!

    Your T-Maxx combines automatic, two-speed shifting in forwardand reverse, with powerful four-wheel disc braking. Thepatented transmission design and three-channel TQ-3 radiosystem put these functions right at your fingertips.

    The new TRX 2.5 Racing Engine is the most powerful engine ofits size ever available in a Ready-To-Run truck. Two years ofengineering development and advanced design, along withthousands of hours of testing, puts the TRX 2.5 in a class byitself. Each part of the TRX 2.5from the air filter on the slidecarburetor, to the tip on the dyno-tuned exhaust systemhasbeen carefully engineered to provide maximum power over thebroadest RPM range.

    Traxxas was the first with standard on-board electric starting.The new second generation EZ-Start has evolved into anincredibly advanced and reliable starting solution, featuringthermal protection for the motor and built-in diagnostics tomonitor the condition of the glow plug.

    Obviously, theres much going on between the wheels of yourT-Maxx. In this manual, well take you step-by-step through allnecessary set-up, break-in, tuning, and operating procedures.Even if you are an experienced R/C enthusiast, it isimportant for you to read and follow the procedures in thismanual. Pay particular attention to the fuel requirementsand break-in procedures. The advanced design of the TRX2.5 engine does not follow old-fashioned thinkingregarding fuel and break-in procedures.

    4 Before You Proceed

    5 Safety Precautions

    6 Tools, Supplies and RequiredEquipment

    7 Anatomy of the T-Maxx

    8 Quick Start: GettingUp to Speed

    9 Gluing the Tires

    10 Decorating Your T-Maxx

    11 The Traxxas TQ-3Radio System

    21 The TRX 2.5 Engine

    37 Driving the T-Maxx

    38 Adjusting Your T-Maxx

    42 Trouble ShootingYour T-Maxx

    44 Maintainingand Storing Your T-Maxx

    46 Index

    3

  • Before You Proceed

    Carefully read and follow all instructions in this and anyaccompanying materials to prevent serious damage to yourT-Maxx. Failure to follow these instructions will be consideredabuse and/or neglect.

    Before running your T-Maxx, look over this entire manual, andexamine the truck carefully. If for some reason you decide theT-Maxx is not what you wanted, then do not continue anyfurther. Your hobby dealer absolutely cannot accept aT-Maxx for return or exchange after it has been run.

    Warnings, helpful hints, and cross-referencesThroughout this manual, youll notice warnings and helpfulhints, identified by the icons below. Be sure to read them!

    An important warning about personal safety or avoidingdamage to your T-Maxx and related components.

    Special advice from Traxxas to make things easier andmore fun.

    Refers you to a page with a related topic.

    SupportIf you have any questions about your T-Maxx or its operation,call the Traxxas Technical Support line toll-free at:1-888-TRAXXAS (1-888-872-9927)

    Technical support is available Monday through Friday from8:30am to 9:00pm central time. Technical assistance is alsoavailable at www.Traxxas.com. You may also e-mail customersupport with your question at [email protected]. Jointhousands of Traxxas R/C enthusiasts in our online communityat ReadyToRun.org

    Traxxas offers a full-service, on-site repair facility to handle anyof your Traxxas service needs. Maintenance and replacementparts may be purchased directly from Traxxas, or you can saveshipping and handling costs by purchasing them from yourlocal hobby dealer.

    4

  • All of us at Traxxas want you to safely enjoy your new T-Maxx.Operate your T-Maxx sensibly and with care, and it will beexciting, safe, and fun for you and those around you. Failure tooperate your T-Maxx in a safe and responsible manner mayresult in property damage and serious injury. The precautionsoutlined in this manual should be strictly followed to helpensure safe operation. You alone must see that the instructionsare followed and the precautions are adhered to.

    Important Points to Remember R/C fuel is dangerous and highly poisonous. Always follow alldirections and precautions printed on the fuel container.

    R/C fuel, especially when in a fuel dispensing bottle, maylook like a cool drink to a child. Keep all fuel out of the reachof children at all times. Do not place fuel containers on theground where children can get to them while you aredriving.

    R/C fuel is flammable. Never allow smoking, sparks, heat orflame in the presence of fuel or fuel vapors.

    The engine and exhaust system may become extremely hotduring use. Be careful not to touch the parts, especially whenrefueling or stopping the engine.

    Prolonged exposure to the engine exhaust can be harmful.Avoid breathing the engine exhaust. Always run your T-Maxxoutdoors, in a well-ventilated area. Never run the engineindoors.

    Dont operate your T-Maxx at night, or anytime your line ofsight to the model may be obstructed or impaired in any way.

    Never operate your T-Maxx in crowds of people or busypedestrian areas. The T-Maxx is large and fast, and may causeinjury to those unaware of its presence.

    Because the T-Maxx is controlled by radio, it is subject toradio interference from many sources beyond your control.Since radio interference can cause momentary loss ofcontrol, always allow a safety margin in all directions aroundyour model to prevent collisions.

    The engine can be loud. If the noise makes youuncomfortable, wear ear protection. Be considerate of yourneighbors by not running your model early in the morningor late in the evening.

    Most importantly, use good common sense at all times.

    All instructionsand precautionsoutlined in this

    manual should be strictlyfollowed to ensure safeoperation of your T-Maxx.

    The T-Maxx is notintended for useby those under 16

    years of age without thesupervision of aresponsible andknowledgeable adult.

    5

    Safety Precautions

  • Tools, Supplies, and Required Equipment

    Your T-Maxx comes with a set of specialty metric tools. Youllneed to purchase other items, available from your hobby dealer,to operate and maintain your model.

    For more info onbatteries, see Usethe Right Batteries

    on page 13.

    A peak-detectingcharger isrecommended for

    best performance andlongest battery life. Formore information, see Usethe Right Charger on page30.

    12 AA alkaline batteries for the radio system

    7.2-volt NiCad battery pack for the EZ-Start starting system

    NiCad battery charger

    Traxxas Top Fuel

    10% quart - #5010 20% quart - #502010% gallon - #5060 20% gallon- #5070

    Fuel dispensing bottle (Traxxas part #5001)

    TRAXXAS

    1.5mm hex wrench

    2.0mm hex wrench

    Glow plug (universal) wrench

    Turnbuckle wrenches

    Batteries

    Fuel

    Supplied ToolsYour T-Maxx comes with these specialty metric tools:

    Other Required Tools and Supplies

    Thin, hobby-quality cyanoacrylateinstant tire glue (often called CA glue)

    Safety glasses

    #2 Phillips screwdriver

    After-run oil (WD-40) to protect the engine from corrosion

    #1 Phillips screwdriver

    Small flat-blade screwdriver (1/8 inch blade)

    Filter oil (for the foam air filter) see page 27 for details

    Hobby knife

    6

  • Anatomy of the T-Maxx

    BatteryBox

    FuelTank

    Fuel Tank Lid

    SteeringServo

    Shifting Servo

    SuspensionArm (upper)

    Bumper(Front)

    BumperMount

    Skid Plate(front)

    Cross-brace

    Shock(Oil Damper)

    Differential

    TurnbuckleThrottle/BrakeServo

    ReceiverBox

    Transmission

    AirFilter

    Pipe

    Header Enginesee pg. 20 for details

    Pressure Line

    Fuel Line

    EZ-StartMotor

    EZ-StartPlug

    Bulkhead

    ShockTower

    BodyMount

    SpurGear

    Chassis

    7

    SlipperClutch

    Half Shaft

    On/OffSwitch

    ShiftRod

    Access Plugfor Receiver Crystal

    AntennaMount

    PipeHanger

    Access Plugfor Two Speed

    Adjustment

  • The following guide is an overview of theprocedures for getting your T-Maxx running,

    from opening the box to breaking in and tuning your engine.Refer to the pages indicated for details on each step. Look for theQuick Start logo on the bottom corners of Quick Start pages.

    1. Charge the battery pack See sidebar, page 30 The EZ-Start requires a fully charged 7.2-volt battery pack (not included).

    2. Get the right fuel See page 26Use Traxxas Top Fuel or consult with Traxxas before using other fuels.

    3. Glue the tires See page 9Glue the tires to the rims to prevent the rims from spinning inside the tires.

    4. Install the antenna See page 15Install the antenna mast in the T-Maxx.

    5. Decal and Install the body See page 10You will need to use the body during the break-in process so its best to decal it before you use it on the truck.

    6. Install batteries in the transmitter See page 13The T-Maxx requires 8 AA alkaline or rechargeable batteries for the transmitter.

    7. Install batteries in the model See page 14The T-Maxx requires 4 AA alkaline or rechargeable batteries for the receiver.

    8. Install the EZ-Start battery See page 30Install and connect the 7.2-volt battery pack in the EZ-Start controller.

    9. Turn on the radio system See page 18Make a habit of turning the transmitter on first, and off last.

    10. Check servo operation See page 19Make sure the throttle, shifting, and steering servos areworking correctly.

    11. Range test the radio system See page 20Follow this procedure to make sure your radio systemworks properly at a distance and that there is nointerference from outside sources.

    12. Fill the fuel tank See page 26Use your fuel-dispensing bottle to fill the tank.

    13. Connect the EZ-Start to the model See page 31Learn the proper way to use the EZ-Start electric startingsystem

    14. Start the engine See page 32Learn to use the correct starting procedure for your TRX 2.5.

    15. Break-in your engine See page 32Follow the break-in instructions exactly to ensure the best-performing, longest-lasting engine.

    16. Tune your engine See page 34Learn how to set the fuel mixture needles for optimum engine performance.

    17. Drive your T-Maxx See page 37Learn how to use the two-speed and reverse functionson your T-Maxx

    18. Maintaining your T-Maxx See page 44Follow these critical steps to maintain the performanceof your T-Maxx and keep it in excellent runningcondition.

    The Quick StartGuide is notintended to

    replace the full operatinginstructions available inthis manual. Please readthis entire manual forcomplete instructions on the proper use andmaintenance of your T-Maxx.

    Quick Start: Getting up to Speed

    8

  • The tires on your T-Maxx must be glued to the rims using CA tireglue to prevent the rims from spinning inside the tires. You canglue the tires without removing the wheels from the truck. Forclarity, these instructions show the process with the wheelsremoved.

    1. Remove a wheel from theT-Maxx using the larger(8mm) end of the glow plug(universal) wrench.

    2. Use your thumb to push theside of the tire away from therim. Place one or two drops ofCA glue into the opening andrelease the tire. Capillaryaction will draw the gluearound the bead of the tire.

    3. Repeat step two at four or five points around the rim, until thetire is completely secured to the rim. Turn the rim over andrepeat the process for the inside of the rim/tire. Repeat for theother 3 wheels.

    4. Reinstall the wheels, makingsure none of the axle pinshave fallen out from behindthe hex hubs.

    Always wear safetyglasses to preventglue from

    splattering into your eyes.

    The acetone infingernail polishremover will

    remove excess glue fromyour fingers.

    For best resultswhile gluing, cleanthe bead of the

    tires and the grooves ofthe wheels with denaturedalcohol before applyingglue. This removes anymold release agent residuefrom the tires and wheels,providing a better bond.

    Gluing The Tires

    9

    Hub

    Axle Pin

  • Decorating Your T-Maxx

    Applying The Decals

    The ProGraphix paintedbody is covered with aprotective film for shipping.You must remove this filmbefore applying any decals.

    To remove the film, lift acorner of the film andcarefully pull it off the bodyin one continuous piece.

    Your T-Maxx decals are die-cut for easy removal. Use ahobby knife to lift thecorner of a decal and lift itfrom the backing.

    Carefully position the decalover the desired locationand press one side on thebody. Pull the decal tightand use a finger to graduallysmooth out any air bubblesas you apply the decal.

    Look at the photos on the box for typical decal placement.

    10

  • 11

    The Traxxas TQ-3 Radio System

    Your T-Maxx (model 4910) is equipped with the TQ-3 RadioSystem. The TQ-3 is a 3-channel system that provides high-power output up to a quarter mile and control for up to threeservos.

    CH.3

    CH.2

    CH.1

    Antenna Throttle Neutral Adjust

    Steering Wheel

    Throttle Trim

    Steering Trim

    Reverse Shift

    Forward Shift

    Power SwitchPower Indicator

    Battery Compartment

    ServoReversingSwitches

    Throttle Trigger

    T-Maxx WiringDiagram

    AntennaOn/OffSwitch

    BlackNegative

    RedPositive

    Receiver

    4-CellBattery Holder

    Channel 1Steering Servo

    Channel 2Throttle Servo

    Channel 3Shifting Servo

    Channel 3Channel 2 Channel 1

    Battery

  • Radio System TerminologyPlease take a moment to familiarize yourself with these radio-system terms. They will be used throughout this manual.

    Channel - The 27 MHz frequency band is divided into 6channels so that up to six models can be operatedsimultaneously. Each channel is referred to by its flag color andchannel number, as shown below.

    Clearing your frequency - A routine, verbal check to make surenobody else in your area is operating on the same channel.Always clear your frequency by calling out your channelnumber before operating your model. Wait or move toanother area if your channel is already being used.

    Crystal (X-tal) - The plug-in device that determines whichchannel the radio system will operate on. For each channel,there are two crystals, one for the receiver and one for thetransmitter. Of those two crystals, the one marked with thelower number (.455 MHz lower) must be inserted into thereceiver.

    Frequency band - The radio frequency used by the transmitterto send signals to your T-Maxx. All Traxxas RTR models operateon a 27 MHz frequency band.

    Neutral position - The standing position that the servos seekwhen the transmitter controls are at the neutral setting.

    NiCad - Refers to rechargeable, nickel-cadmium batteries. Themost economical choice, since they may be recharged up to500 times.

    Receiver - The radio unit inside your T-Maxx that receivessignals from the transmitter and relays them to the servos.

    Servos - Small motor units in your T-Maxx that operate thethrottle, shifting, and steering mechanisms.

    Three-channel radio system - The TQ-3 radio system,consisting of the receiver, the transmitter, and the servos. Thesystem uses three channels: one to operate the throttle, one toshift the transmission, and one to operate the steering.

    Transmitter - The hand-held radio unit that sends throttle andsteering instructions to your T-Maxx.

    Trim - The fine-tuning adjustment of the neutral position of theservos, made by turning the throttle and steering trim knobson the face of the transmitter.

    Channel Frequency Band Flag Color Traxxas Part No.

    1 26.995 Brown 2031

    2 27.045 Red 2032

    3 27.095 Orange 2033

    4 27.145 Yellow 2034

    5 27.195 Green 2035

    6 27.255 Blue 2036

    Learn terms relatedto the TRX 2.5engine beginningon page 23.

    The Traxxas TQ-3 Radio System

    12

  • 13

    The Traxxas TQ-3 Radio System

    Installing Transmitter BatteriesYour TQ-3 transmitter uses 8 AA batteries. The batterycompartment is located at the base of the transmitter.

    1. Remove the battery compartment door by pressing thetab and lifting the door up.

    2. Install the batteries in the correct orientation as indicatedin the battery compartment.

    3. Reinstall the battery door and snap it closed.

    4. Turn on the transmitter and check the power indicator fora solid red light.

    If the power indicator light flashes, then the transmitterbatteries are weak, discharged or possibly installed incorrectly.Replace with new or freshly charged batteries. The powerindicator light does not indicate the charge level of thereceiver batteries in the model.

    Use the Right BatteriesYour transmitter and receiveruse AA batteries. Use newalkaline batteries, orrechargeable batteries such asNiCad or Ni-MH (nickel-metalhydride) batteries in yourtransmitter and receiver. Makesure rechargeable batteries arefully charged according to themanufacturers instructions.

    If you use rechargeable batteries in your transmitter, beaware that when they begin tolose their charge, they losepower much more quickly thanregular alkaline batteries. Caution: Discontinuerunning your T-Maxx at thefirst sign of weak batteries(flashing red light) to avoidlosing control.

    If the power indicatordoesnt light red, checkthe polarity of the

    batteries. Check rechargeablebatteries for a full charge.

    CH.3

    CH.2

    CH.1

  • Installing Receiver BatteriesThe radio receiver in your T-Maxx uses 4 AA batteries. The batteryholder for the receiver batteries is located underneath the batterycover. The battery cover can be identified by the on/off switch.

    1. Remove the battery cover by removing the two 3x10mmroundhead self-tapping screws from the cover.

    2. Remove the battery holder and install 4 AA alkaline batteries.Make careful note of the battery polarity by comparingagainst the diagrams in the battery holder.

    3. Insert the battery holder into the battery cover.

    4. Reinstall the battery cover and secure with the screws (see sidebar!).

    On/Off Switch

    4-cellbatteryholder

    Direct the batterywires through theslot in the battery

    cover. If the wires are notproperly routed, they maybecome broken or shorted,causing radio systemfailure and loss of control.

    If you use rechargeable batteries in your receiver,be aware that when theybegin to lose their charge,they lose power much morequickly than regularalkaline batteries. Signs ofweak receiver batteriesinclude sluggish steeringresponse and shortenedradio range. Caution:Discontinue running yourT-Maxx at the first sign ofweak batteries to avoidlosing control.

    If the radio systemdoesnt appear towork when the

    transmitter and receiverswitches are turned on,check for correct batteryinstallation.

    The Traxxas TQ-3 Radio System

    14

  • The Traxxas TQ-3 Radio System

    15

    Spray a little windowcleaner on theantenna wire to

    make it easier to pushthrough the antenna tube.

    Dont shorten thelength of theantenna wire. Its

    length is tuned to thefrequency band; cutting itcould severely shorten theradio systems range.

    Dont push thetransmitter antennadown from the top.

    Pull it down from thebottom, one segment at atime, to prevent binding andkinking the antenna mast.

    Setting Up the AntennaYou must install the antenna mast (tube) before you operateyour T-Maxx. Youll find the plastic antenna tube and tip in thebag with your manuals and documentation.

    1. Locate the black antenna wire that exits the receiver cover.The T-Maxx receiver cover is mounted on the top of thechassis, near the front.

    2. Pull the wire straight with your fingers and then insert theend of the wire into one end of the antenna tube. Push thewire all the way through the antenna tube.

    3. Pull the remaining wire through the antenna tube, and theninsert the base of the antenna tube into the molded post ontop of the receiver cover.

    4. Fold the remaining antenna wire over the top of the tubeand secure it with the antenna tip.

    5. On the transmitter, always fully extend the telescopingantenna when running your T-Maxx. Make a habit of holdingthe transmitter so that the antenna points straight up.

    Antenna Tip

    Antenna Tube

  • The Traxxas TQ-3 Radio System

    CH.3

    CH.2

    CH.1

    ACCELERATE BRAKE

    LEFT

    NEUTRALRIGHT

    CH.3

    CH.2

    CH.1

    SHIFTREVERSE

    SHIFTFORWARD

    TQ-3 Radio System Controls

    16

  • The Traxxas TQ-3 Radio System

    17

    Other TQ-3 Radio System AdjustmentsIn addition to the electronic throttle and steering trim controls,your radio system features throttle neutral adjustment andservo reversing switches.

    Throttle Neutral AdjustmentThe throttle neutral adjustment is located on the transmitterface and controls the forward/reverse travel of the throttletrigger. Change the adjustment by pressing the button andsliding it to the desired position. There are two settingsavailable:

    50/50: Allows equal travel for both acceleration and braking.

    70/30: Allows more throttle travel (70%) and less

    brake travel (30%).

    50/50 is the required setting for the T-Maxx with the TRX 2.5 racing engine.

    Electronic Throttle TrimThe electronic throttle trim located on the face of thetransmitter adjusts the neutral (center) point of the throttleservo when the servo is at rest. This control has been preset foryou at the factory. If necessary, adjust the control so that thecarburetor is at idle, and the brakes are not applied (the model

    will roll freely). Do not use the throttle trim to raise or lower theengine idle speed. Make the idle speed adjustment on thecarburetor.

    Electronic Steering TrimThe electronic steering trim located on the face of thetransmitter adjusts the neutral (center) point of the steeringservo when the servo is at rest. Adjust this control to make themodel drive straight with no steering input at the wheel.

    Servo Reversing SwitchesThe servo reversing switches are located on the front of thetransmitter, next to the on/off switch. Moving a switch reversesthe direction of the corresponding servo.

    Each switch corresponds to a channel, as shown below. Forexample, if you turn the steering wheel to the right and yourfront wheels turn left, you would move the channel 1 switch tocorrect the servo direction. It may be necessary to adjust thecorresponding trim control after moving a switch.

    CH.3

    CH.2

    CH.1

    Channel Servo1 Steering2 Throttle and braking3 Shifting

  • TQ-3 Radio System RulesEach time you prepare to run yourT-Maxx, you must clear your frequencyto be sure no one else in the area isusing the same channel as you.

    There are six possible channels,numbered 1 through 6. Each isrepresented by a color. Look at thecrystal plugged into the back of yourtransmitter to determine which channelyour truck is assigned to.

    Always turn your TQ-3 transmitter on first and off last. Thisprocedure will help to prevent your T-Maxx from receivingstray signals from another transmitter, or other source, andrunning out of control.

    Always have the transmitter and receiver turned on beforeyou start the engine. Never turn the radio system off whilethe engine is running. The on/off switch in the model onlyturns the receiver on and off. It does not turn off the engine.

    Always use new or freshly charged batteries for the radiosystem. Weak batteries will limit the range of the radio signalbetween the receiver and the transmitter. Loss of the radiosignal can cause you to lose control of your T-Maxx.

    Channel 1Brown

    Channel 2Red

    Channel 3Orange

    Channel 4Yellow

    Channel 5Green

    Channel 6Blue

    CH.3

    CH.2

    CH.1

    1 2 3

    Remember, alwaysturn the TQ-3transmitter on first

    and off last to avoiddamage to your T-Maxx.

    18

    The Traxxas TQ-3 Radio System

  • The Traxxas TQ-3 Radio System

    Using the TQ-3 Radio SystemThe TQ-3 Radio System was pre-adjusted at the factory. Theadjustment should be checked, before running the model, incase of movement during shipping. Heres how:

    1. Fully extend the chrome antenna mast on the transmitterand turn the switch on. The red indicator light on thetransmitter should be solid red (not flashing).

    2. Turn on the receiver switch in the model. The switch islocated on the battery cover.

    3. Position the T-Maxx so that its front wheels are off theground.

    4. Turn the steering wheel on the transmitter back and forthand check for rapid operation of the steering servo. Also,check that the steering mechanism is not loose or binding. Ifthe steering operates slowly, check for weak receiverbatteries.

    5. When looking down at model, the front wheels should bepointing straight ahead. If the wheels are turned slightly tothe left or right, slowly adjust the steering trim control on thetransmitter until they are pointing straight ahead.

    6. Operate the throttle trigger on the transmitter and check forrapid operation of the throttle servo. When the throttletrigger is pulled back, the carburetor should open. When thethrottle trigger is pushed all the way forward, the brakeshould lock.

    7. Operate the shift button on the transmitter and check forrapid operation of the shifting servo. Push the shift buttondown for forward. The servo will push the transmission shiftrod into the transmission. Push the shift button up for reverseand the servo will pull the shift rod out of the transmission.

    8. Once adjustments are made, turn off the receiver on yourT-Maxx, followed by the handheld transmitter.

    Throttle/BrakeServo

    Shifting Servo

    Steering Servo

    Throttle

    Brake

    00

    T-Maxx ServoOperation

    When the engineis running, dontuse the throttle

    trim on the transmitter toadjust the engine idlespeed. Instead, use theidle speed adjustment onthe carburetor.

    Because yourT-Maxx featureszero-scrub-radius

    suspension and wide tires,the steering servo will notfully turn the front wheelswhen the vehicle is notmoving.

    19

  • The Traxxas TQ-3 Radio System

    Range-Testing the TQ-3 Radio SystemBefore each running session with your T-Maxx, you should range-test your radio system to ensure that it operates properly.

    1. Turn on the radio system and check its operation as describedin the previous section (Using Your Radio System, pages 17- 19).

    2. Have friend hold the model with the engine off.

    3. Make sure your transmitter antenna is fully extended, and thenwalk away from the model with the transmitter until you reachthe farthest distance you plan to operate the model.

    4. Operate the controls on the transmitter once again to be surethat the model responds correctly.

    5. Do not attempt to operate the model if there is any problemwith the radio system or any external interference with yourradio signal at your location.

    Dont attempt tooperate yourT-Maxx if there are

    any problems with yourradio system or radiointerference at yourlocation.

    20

  • IntroductionTheres nothing like the TRX 2.5 engine in your new T-Maxx.The TRX 2.5 engine is vastly superior to typical R/C engines andbelongs in the category of specialty high-performance racingengines. Its the result of years of focused engineeringdevelopment, and thousands of hours of controlled testing and rigorous real-world running. It offers unprecedented powerand performance that turns ready-to-run into Ready-To-Race.

    The TRX 2.5 racing engine takes a total-system approach. Eachpart of the engine, from the air filter to the exhaust tip, iscarefully engineered to work in harmony with other enginecomponents. Each part complements the next, to extractmaximum power. The TRX 2.5 is designed to be tolerant ofvariations in tuning, and to run successfully through a widerange of variable atmospheric conditions, such as changes intemperature, humidity, and altitude.

    The TRX 2.5 is manufactured to exacting tolerances and requiresa specially-designed break-in procedure to accomplish the finalprecision fitting of the internal engine components. It is veryimportant that you follow the new break-in procedure as closelyas possible to achieve the best performance and longest lifefrom your TRX 2.5 racing engine. Old style break-in procedures,such as simply running the engine with a very rich fuel mixturefor the first 4 tanks of fuel, will not achieve the best results.Follow the steps in this manual.

    A routine maintenance schedule is also required to keep theTRX 2.5 in top running condition. Cleaning the air filter aftereach hour of running is particularly important. Also it isextremely important to perform after-run maintenance on theengine to prevent corrosion from building up on the internalengine components (see page 44).

    Traxxas stronglydiscourageschanging or

    modifying any part of theTRX 2.5 engine. Old techtips and tricks that mayhave boosted the power ofother engines couldseriously diminish theperformance of the TRX 2.5.

    Theres more advancedthinking, development andtesting in the stock parts ofyour TRX 2.5 than in manyaftermarket manufacturersso-called performanceparts. The TRX 2.5 is alreadythe most powerful enginesin its class and simply willnot benefit from average,low-tech, aftermarket bolton performance items.

    The TRX 2.5 Racing Engine

    21

  • The TRX 2.5 Racing Engine

    TRX 2.5 IllustratedAir

    FilterHead Protector

    Head (Cylinder head)

    EZ-StartDrive Unit

    EZ-StartMotor

    EngineMountLow-Speed

    NeedleThrottle

    Arm

    ClutchBell

    Flywheel

    Carburetor

    Air Intake

    Fuel Intake

    High-Speed Needle

    Idle SpeedScrew

    EZ-StartPlug

    PositiveWire

    NegativeWire

    Fuel Line

    Fuel Tank

    Pipe

    ExhaustTip

    PressureLine

    GroundWire

    Glow PlugWire

    EZ-StartController

    22

    Crankshaft

    Crankcase

  • The TRX 2.5 Racing Engine

    Terms to KnowYoull find these Nitro R/C engine terms throughout thissection of the manual.

    .15 - .15 or 15 refers to the size of the engine. The TRX 2.5 is .15cubic inches or 2.5 cubic centimeters (cc). The name TRX 2.5is derived from the cc measurement.

    ABC - Abbreviation for aluminum, brass, and chrome. Refers toengine construction that consists of an aluminum piston thatslides in a chrome-plated brass sleeve. The TRX 2.5 uses ABCconstruction.

    Air filter - The air filter sits atop the carburetor and preventsharmful dust and dirt from entering the engine. Dirt ingestionis the number one cause of premature engine failure so theengine should never be run without the air filter in place.

    Big Block .15 - A .15 (2.5) engine that uses a larger crankcasesize and longer stroke than typical .15 engines. Generally onlyused for specific racing classes.

    Break-in - Break-in is the procedure for running a brand newengine according to specific instructions. This correctlyprepares the engine for normal running. The break-inprocedure can be different for different makes of engines.Follow the Traxxas directions for break-in exactly.

    Carb - Abbreviation for carburetor.Carburetor - The carburetor atomizes (mixes) the fuel with the

    air so that the engine can burn it. There are two types ofcarburetors, slide carbs and barrel carbs. The TRX 2.5 uses thesuperior slide carburetor design.

    Clean-out - Cleaning-out is a condition that occurs when theengine is accelerating and the fuel mixture becomessufficiently lean to allow the engine to continue into its upperRPM power band. Usually characterized by a noticeabledecrease in blue exhaust smoke and a dramatic increase inengine speed.

    Combustion chamber - The combustion chamber is machinedinto the bottom of the cylinder head. This is where the glow

    plug ignites the fuel. The shape of the combustion chamber isdesigned to promote more efficient burning of the fuel.

    Connecting rod - The connecting rod transfers the pistonmotion to the crankshaft. The TRX 2.5 racing engine uses aknife-edged connecting rod. The aerodynamic, sharpenededges allow it to slice through the pressurized air/fuelmixture inside the crankcase.

    Cooling fins - The cooling fins are molded into the cylinderhead and crankcase and cause heat to be drawn away fromthe engine. Heat is removed when it dissipates into the airpassing across the cooling fins. It is important to keep the finsclean of dirt and debris for maximum cooling efficiency.

    Crankcase - The engine body that contains all of the runningmechanical components.

    Crankshaft - The main shaft of the engine that contains therotating assembly.

    Cylinder head (head) - The finned aluminum part on top of theengine that is responsible for dissipating most of the enginesheat. The combustion chamber is machined into the bottom ofthe head.

    Dyno - Abbreviation for dynamometer. A precise piece oftesting equipment that accurately measures engine powerand torque output over the engines entire RPM range.

    EZ-Start - Second generation Traxxas on-board electric startingsystem. The system consists of a hand held starter control unitand an on-board gearbox with an electric motor to spin theengine. The new EZ-Start contains many performance andreliability improvements over the first generation EZ-Start.

    Filter foam - The oiled foam element inside the air filterhousing. The filter foam in the TRX 2.5 must be thoroughlycleaned and re-oiled after every hour of run time.

    Fit - Usually refers to the fit of the piston and sleeve. If the fit istight, then the piston will feel very tight at top of the sleeveand the engine will have good sealing and compression. If thefit is loose, then compression will be low and the piston andsleeve should be replaced.

    Learn terms relatedto the TQ-3 RadioSystem on page 12.

    23

  • The TRX 2.5 Racing Engine

    Flame-out - Occurs when the engine stops running at highRPM. Usually the fault of an excessively lean fuel mixture orglow plug failure.

    Fuel - (10% 20%) The TRX 2.5 must have model engine fuel torun. Traxxas Top Fuel is recommended. Fuel is sold in quartsand gallons from hobby dealers. The 10 and 20% labelingrefers to the percentage amount of nitromethane contained inthe fuel (see nitro percentage definition).

    Fuel mixture - The ratio of fuel to air as determined by theneedle settings of the carburetor.

    Fuel tubing (fuel line) - The thick silicone tubing that carriesfuel from the fuel tank to the carburetor.

    Glow plug - The glow plug is located in the cylinder head at thetop of the combustion chamber. It contains a platinumelement that glows red hot when voltage is applied. When theengine is being started, the heat from the glow plug ignitesthe fuel mixture and starts the combustion process.

    Glow plug driver - This tool clips onto the glow plug andsupplies the required voltage to light the glow plug element. Itis also called an igniter. EZ-Start equipped engines do notrequire this separate tool.

    Header - The aluminum tube that connects the exhaust systemto the engine exhaust port. The length and diameter of theheader must be carefully selected to extract the most powerfrom the engine.

    High-speed needle - Adjusts the carburetors fuel/air mixture athigh RPM.

    Idle speed - The speed (RPMs) the engine runs at when thetransmitters throttle trigger is at neutral.

    Idle speed screw - Located on the carburetor body. This screwadjusts the idle RPM of the engine.

    Lean - A running condition where the engine is not gettingenough fuel (for the available air). Symptoms include engineoverheating, or the engine runs for a short time and then

    stalls, particularly at high speed. This is a dangerous condition that should be corrected immediately or it canruin your engine.

    Leaning the mixture - Turning either the high speed and/orlow-speed needle(s) clockwise to decrease the amount of fuelthe engine receives.

    Low-speed needle - Needle valve that controls the low-speedfuel mixture.

    Needle valve - Valve consisting of a tapered needle that closesagainst a corresponding seat to regulate fuel flow.

    Nitro - Abbreviation for nitro methane, a component of modelengine fuel that improves fuel combustion and power output.Nitro also refers to a class of RC powered by model enginesinstead of electric.

    Nitro content - The amount of nitro methane used in the fuel.Usually measured as a percentage of the total fuel volume.Traxxas engines are optimized to use 10-20% nitro. 30% nitromay be used for racing.

    Nitromethane - Nitro methane is a component in the fuel thatincreases power from the combustion process up to a point.Engines are generally optimized to use a range of nitrocontent for the best power.

    O-ring - Rubber O-shaped ring used as a sealing gasket.Pipe - Abbreviation for the tuned exhaust pipe on a nitro

    engine. See Tuned Pipe definition.Piston - The piston is the internal engine part that is attached to

    the upper end of the connecting rod and moves up and downin the cylinder sleeve. The precise fit between the piston andthe sleeve creates a seal that allows engine to have therequired compression for combustion.

    Port - Ports are openings in the sleeve that allow atomized fuelto enter the combustion chamber and burned exhaust gassesto exit. The shape and location of the ports are a large factor incontrolling the engine timing and power output.

    24

  • Priming - Manually causing fuel to move from the fuel tank upto the carburetor. This is sometimes necessary after the enginehas been sitting for a long period of time and all the fuel hasdrained back to the tank. On a Traxxas model this is done byholding your finger over the exhaust tip for one or twoseconds while the engine is starting.

    Punch - A term that refers to how quickly the model respondsto throttle input or how quickly it accelerates.

    Rich - A running condition where the engine is getting toomuch fuel for the available air. It is better to run an engineslightly rich to increase engine life. Excessively rich mixturescause the engine to have sluggish performance withexaggerated blue smoke and unburned fuel coming from theexhaust.

    RPM - Abbreviation for revolutions per minute (how many timesthe engine crankshaft spins in a minute).

    Sleeve - Internal engine part that contains the piston. Theprecise fit between the sleeve and the piston creates a sealthat allows engine to have the required compression forcombustion. The sleeve in a TRX engine is made of brass and isthen hard-chrome plated.

    Slide carburetor - The throttle on a slide carburetor closes andopens by sliding a barrel in and out of the carburetor body.This type of carburetor is preferred for performance usebecause it provides a less restrictive straight-through air paththan the barrel carburetor design.

    Stall - When the engine stops running, usually due to anincorrect fuel mixture setting or running out of fuel.

    Tuned pipe - The tuned exhaust pipe usually consists of aspecially-shaped metal or composite chamber with bafflesthat is designed to enhance the power output of the engine.

    Wear-in - Fitment process that occurs during engine break-inwhere internal engine parts develop an even more precisematched fit through actual use under controlledcircumstances.

    WOT - Abbreviation for wide-open throttle.

    The TRX 2.5 Racing Engine

    25

  • The TRX 2.5 Racing Engine

    The FuelUse the Right FuelIts imperative that you use the correct fuel inyour TRX 2.5 for maximum performance andengine life. Traxxas Top Fuel should be used to ensure correct engine lubrication,performance, and ease of tuning. Traxxas TopFuel has been proven in thousands of engines,so you can count on it every day for greatperformance.

    Top Fuel is the only fuel which is 100% certified for use inTraxxas engines.Traxxas Top Fuel is made with just the right balance of thehighest grade natural and synthetic lubricants to allowexcellent throttle response and the best top-endperformance, without sacrificing long-term durability.All of the components in the fuel are carefully selected fromthe best materials available and then custom blended tomatch the metallurgy and temperature characteristics ofTraxxas engines.

    You may use 10% or 20% nitro-content fuel. Use the samepercentage all the time; dont switch back and forth between10% and 20% fuel. If you break-in your engine on 20% fuel, thenalways use 20% fuel.

    What about Other Fuels?Can other brands of fuel be used besides Top Fuel? There areother fuels that can provide satisfactory performance; howeverthere could be long-term costs in the form of decreased engineperformance, loss of tuning ease, and shorter engine life.

    Everyone has an opinion or a claim to make about fuel. Theengineering team at Traxxas spent over 2-years developing theTRX 2.5 engine. No one knows more about the specific fuelrequirements of Traxxas engines, than Traxxas engineers. Westrongly urge you not to take chances with your engineinvestment and use the Traxxas fuel made for the TRX 2.5.

    Handling the FuelFollow all directions and warnings on the fuel can.Keep the fuel tightly capped at all times. Some componentsin the fuel can evaporate very quickly and upset the balanceof the fuel.Do not store unused fuel in the fuel dispenser. Immediatelyreturn fresh unused fuel back into the fuel can.Do not mix old and new fuel. Never mix different brands offuel together.Store the fuel in a cool dry location, away from any source ofheat, ignition, or combustion.Read and follow the safety precautions on page 5in this manual.

    Filling the Fuel TankUse a fuel dispensing bottle (Traxxas TopFueler, part# 5001) to put fuel into theT-Maxxs fuel tank. To fill the fuel bottle,squeeze the air out, insert the dispensertip into the fuel can, and release your gripon the bottle. As the bottleexpands, fuel will bedrawn into it.

    To fill your model flip upthe spring-loaded cap onthe fuel tank, insert the tipof the fuel bottle, andsqueeze to dispense thefuel. Fill the tank until thefuel level reaches the base of the filler neck. Close the fuel tanklid, making sure it closes tightly.

    Fuel Tank Seal AdjustmentThe rubber seal on the fuel tank is important to the function ofthe engine. The fuel tank is pressurized by the exhaust system toprovide reliable fuel flow. If the tank lid does not seal properly,an air leak will be created that can cause your engine to runerratically and be difficult to start. If necessary, the rubber O-ringtank seal can be adjusted for improved sealing by tighteningthe screw on the underside of the tank lid.

    You may use highernitro percentagesthan 20% in certain

    circumstances. Call 1-888-TRAXXAS for moreinformation.

    26

  • The Air FilterThe TRX 2.5 air filter is carefully designed to deliver maximumperformance while protecting your engine from dust and dirt.Use only the supplied filter. You will not improve engineperformance by switching to an aftermarket filter, and youmay risk engine damage due to poor filtration.

    The TRX 2.5 air filter assembly consists of 3 pieces:

    1. A rubber filter base

    2. A plastic housing consisting of a permanently assembledmesh cap and body

    3. An oiled foam element

    You must clean the filter after every hour of runtime, even if thefilter looks clean. Dust (which is often too fine to see) and dirtconstantly move through the filter anytime the engine isrunning. Even if you cant see dirt on the filter, it is present insidethe foam after any amount of runtime. If you exceed therecommended cleaning intervals, your engine will be damaged.Engine damage or wear due to dirt ingestion is easy to detect,and one of the top causes of premature engine failure.

    Air Filter Cleaning Instructions1. Remove the air filter from the

    carburetor bore by pulling the entire filter firmly to theside to release it.Do not pull straight up

    2. Disassemble the filter. Pull therubber base out of the filterbody.With the base removed, the foam element is visible inthe bottom of the filter body. Pull out the foam element.

    3. Clean the filter parts by thoroughly washing all three pieces ofthe filter assembly in hot soapy water (dishwashing detergentworks well). Repeat twice.

    4. Thoroughly dry the parts with a clean towel or compressed air.Remember to wear your safety glasses when working withcompressed air.

    5. Oil the foam element by saturating it with foam filter oil. Usethe supplied Traxxas filter oil (part# 5263) or a high-quality,special-purpose foam filter oil like what is used for high-performance motorcycle and ATV engines.This type of filter oilis available at motorcycle pro-shops. If foam filter oil is notavailable, clean 30-40 weight motor oil can be substituted, butis not preferred. Never run the engine without a properlyoiled filter! Apply 30 drops of the Traxxas filter oil evenly tothe top, bottom and sides of the filter element (30 total dropsdivided among the 3 surfaces). Squeeze the filter elementrepeatedly to help spread the oil throughout. Squeeze theexcess oil from the foam.The filter element should be evenlycolored by the oil. Even color indicates that the oil is evenlydistributed. Note: Do not use the air filter oil for anythingother than the air filter. It is not meant to be a lubricant.

    6. Reassemble the filter and install it on the engine, making surethe rubber base fits securely on the carburetor with no gaps orair leaks.

    The TRX 2.5 Racing Engine

    Clean your air filterafter every hour ofruntime to avoid

    engine damage, even if thefilter looks clean.

    If you usecompressed air todry your air filter

    assembly, wear safetyglasses and avoid directingcompressed air towardyour skin.

    27

  • The TRX 2.5 Racing Engine

    The CarburetorUnderstanding the Carburetor adjustmentsThe carburetor performs several functions. It controls theengines speed by restricting the intake of air and fuel into theengine. It atomizes the fuel (suspends the fuel droplets in theair) and also controls the air/fuel ratio of the mixture enteringthe engine (how much air for a given amount of fuel).

    To help provide a better understanding of engine tuning andwhy its necessary, the following is a brief explanation of theair/fuel combustion process that takes place inside the engine.

    In order to create the cylinder pressure that results in power, theengine burns the air/fuel mixture. Both air and fuel, in correctamounts, are needed for proper combustion. It is thecarburetors job to mix the air and fuel together (atomize thefuel), in the correct proportion for the best possible combustion.This is the ideal air/fuel ratio. The ideal air/fuel ratio required forthe engine remains roughly constant. Due to variations inatmospheric conditions (temperature, humidity, altitude etc.)fuel flow adjustment valves (called fuel mixture needles) arerequired to meter the fuel and maintain the ideal air/fuel ratio inthese ever-changing conditions. For example, colder air is moredense (more air molecules) for a given volume of air andtherefore requires more fuel (more fuel molecules) to maintain

    the correct air/fuel ratio. Warmer air is less dense (fewer airmolecules) and therefore needs less fuel to maintain the correctair/fuel ratio. The tuning needles are there to adjust how muchfuel is made available for the carburetor to mix with theavailable air (atomization).

    The Fuel Mixture NeedlesThe amount of fuel metered and atomized by the carburetor iscontrolled by the two mixture needles, the high-speed needleand the low-speed needle. The low-speed needle is used tometer the fuel used by the engine at idle and low RPM (part-throttle) engine speed. The high-speed needle is used to meterthe fuel when the throttle is open from part throttle to wide-open throttle (WOT). Two needles on the TRX 2.5 provide precisecontrol of the air/fuel ratio across the engines entire RPM range.

    The maximum possible fuel flow is always controlled by thehigh-speed needle. It works like the main water valve on agarden hose. Turn it clockwise to close the valve, counter-clockwise to open it. When the throttle is at idle or partiallyopen, the low-speed needle again meters the fuel flow at theoutlet (needle seat) where the fuel enters the carburetor venturi.This second valve acts like the spray nozzle at the end of thegarden hose in our example. When you accelerate from idle, thethrottle opens and the low-speed needle is pulled away fromthe needle seat. This allows more fuel to flow with the increasedair flow. As the throttle is increased, the low-speed needle is

    28

    See page 35 formore informationon how air density

    affects engine tuning.

    Air

    Fuel

    Dense Air Less Dense Air

  • pulled completely away from the needle seat leaving it fullyopen. At that point, fuel metering is entirely controlled by thehigh-speed needle. Again, using our water hose example, whenthe spray nozzle at the end of our garden hose is fully open,then the main water valve can be used to adjust how fast thewater flows.

    The engines performance is directly linked to the fuelmixture. Richening the fuel mixture increases the amount offuel in the air/fuel mixture ratio and leaning the fuel mixturedecreases the amount of fuel in the air/fuel mixture ratio.

    Slightly lean fuel mixtures deliver stronger, more efficientcombustion and more power, but with less lubrication.

    Slightly rich fuel mixtures deliver cooler running and morelubrication but with slightly less power.

    Tuning the engine means finding the perfect balance betweenthe two; excellent power to meet your needs while maintaininggood lubrication for long engine life. The optimal fuel mixturesetting is rich to provide a safety margin against having a leancondition if some variable changes (such as the temperaturefrom one day to the next).

    General fuel mixture settings are measured by the number ofturns the needles are turned out from fully closed. The fuelmixture settings have been pre-set from the factory to typicalbreak-in settings. Do not readjust your carburetor from thefactory settings until after the engine is started and running,and you have been able to observe the engine running toassess what minor adjustments may be required to compensatefor fuel, temperature, and altitude. Adjustments are usuallymade in 1/8 or 1/16-turn increments.

    The Idle Speed AdjustmentThe idle speed screw controls the closed position of the throttleslide. When the throttle servo is in its neutral position, thethrottle slide should be stopped against the idle adjustmentscrew. Always use the idle speed adjusting screw to controlengine idle. Do not use the throttle trim on the transmitter toadjust idle speed. The idle speed should be set as low aspossible and still maintain reliable running.

    The TRX 2.5 Racing Engine

    Water Valve(Controls Overall Flow)

    High Speed Needle

    Water Nozzle(Controls Fine Flow)

    Low Speed Needle

    See Tuning YourTRX 2.5 engine forBest Performance

    on page 34 for completeinformation on adjustingthe air/fuel mixture andidle speed.

    If your factorypreset carburetoradjustments have

    been tampered with, usethe following settings: setthe low-speed needle sothat the screw head is flushwith the end of the slide.Set the high-speed needleto 4 turns out from closed.Always use the factorysettings for initial starting.Only use these settingswhen the factory settingshave been lost.

    29

    Lean Rich

  • The TRX 2.5 Racing Engine

    30

    The Traxxas EZ-Start Electric Starting SystemThe Traxxas EZ-Start brings the convenience of push-buttonelectric engine starting to your T-Maxx. The EZ-Start consists of ahandheld control unit and an on-board motorized starter.

    Power for the EZ-Start system comes from a 7.2-voltrechargeable NiCad battery pack installed in the handheldcontrol unit (battery not included).The engine glow plug is heated automatically by theEZ-Start system, eliminating the need to keep up with aseparate glow plug igniter.The voltage to the glow plug is kept constant, regardless ofthe load placed on the starter by the starter motor.The Glow Plug LED (light emitting diode) on the controlunit indicates the condition of the glow plug.The Motor LED indicates the status of the EZ-Start electricstarter motor.The cush drive mechanism in the drive unit preventsdamage to the gears caused by engine kickback.Smart Start protection circuitry prevents damage to themotor by cutting power if the load on the motor or otherelectronics exceeds safe limits.

    Installing the EZ-Start BatteryThe EZ-Start system requires a fully charged 7.2-volt NiCadbattery pack (not included). Use a charger (not included)designed for 7.2-volt battery packs. Charge the batteryaccording to the charger manufacturers directions.

    1. Press the tab in the end of the battery compartment door to open

    2. Plug a fully charged 7.2-volt NiCad battery pack into theconnector inside.

    3. Twist the battery 2 or 3 times to twirl the battery plug wires.This helps hold the wire and battery in place when thebattery is placed in the compartment

    4. Place the battery into the compartment and press the wiressecurely into place.

    5. Slide the battery compartment door back on and lock theend tab.

    Use the Right ChargerThe most convenient

    type of charger is an AC peak-detecting charger that plugsdirectly into an AC walloutlet. It contains specialpeak-detection circuitry thatautomatically shuts thecharger off when the batteryis fully charged.

    If youre using a 15-minutetimed charger, always fullydischarge the battery packbefore each charge. Somehigh mAh battery packs(1500 mAh or higher) requiremore than the standard 15minutes of charge time. If thebattery pack is cold after 15minutes of charging, addanother 5 minutes of chargetime. Closely monitor thebattery pack and stopcharging it when it begins tofeel warm to the touch. Neverleave a battery chargingunattended. Always followcharger manufacturersinstructions.

  • The TRX 2.5 Racing Engine

    Using the EZ-StartYour EZ-Start controller plugs into a 4-prong receptacle in thecenter of the pickup bed on your T-Maxx. When the red buttonon the controller is depressed, the EZ-Start motor begins to spinthe engine, and power from the control unit heats the glowplug. Assuming all settings and preparations are correct, theengine should start almost immediately.

    Each of the two status indicatorLEDs on the handheld control unit,the Motor LED and the Glow PlugLED, should light green whilestarting. If either LED fails to lightwhile starting, there is a faultindicated with that function:

    If the Glow Plug LED fails tolight, the glow plug may be bad,or the glow plug wire may bedamaged or disconnected.

    If the Motor LED fails to lightand the starter fails to operate,then the EZ-Start is inprotection mode.

    Protection ModeThe EZ-Start uses Smart Start technology to monitor thecondition of the system and detect failures. The controllermonitors the load being placed on the EZ-Start motor. If theload becomes excessive, the system shuts off power to themotor to prevent costly damage to the motor and thecontroller. This may occur, for example, if the engine floods withfuel during starting. The starter spins at first but when excessivefuel in the combustion chamber begins to lock up the engine,the starter motor slows under the heavier load. This causes theprotection circuit to shut off the power to the motor. Allow atleast 3 minutes for the starter motor to cool and the circuit toautomatically reset before continuing. Use the time to find andeliminate the condition that caused the excessive load on thestarter motor.

    When the EZ-Startcontroller is inprotection mode, wait

    at least three minutes beforeattempting to start theengine, to give the startermotor time to cool.

    Its normal for yourEZ-Start controller to become warm

    after repeated use.

    See page 43 for information on clearing a

    flooded engine.

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    31

  • The TRX 2.5 Racing Engine

    32

    See ImportantPoints to Rememberon page 5 for other

    precautions.

    Never run yourT-Maxx indoors.Since the TRX 2.5

    engine exhaust fumes areharmful, always run yourT-Maxx outdoors, in a well-ventilated area.

    Your TRX 2.5engine doesntusually require

    priming. If you do need toprime your engine, watchthe fuel line carefully toavoid flooding your engine.See page 43 forinformation on clearing aflooded engine.

    Your carburetor ispre-set at thefactory to give the

    correct air-to-fuel ratio andidle speed for enginebreak-in. Do not adjust thecarburetor unless youobserve a poor runningcondition that requirescorrection.

    Breaking in Your TRX 2.5 Racing EngineThe TRX 2.5 uses a ringless, aluminum-brass-chrome (ABC)piston/sleeve construction.This type of engine design relies on avery precise running fit between the piston and sleeve for cylindersealing. Engine break-in is necessary to allow the piston andsleeve to develop an extremely precise fit and optimum cylindersealing. Therefore, proper engine break-in is critical to achievingthe fastest, most reliable engine performance.

    Allow yourself about 1 to 11/2 hours to complete the break-inprocedure.The engine break-in period will take 5 tanks of fuel in aT-Maxx.The break-in time is not the time to impress your friendswith your new T-Maxx. You must wait until the engine is fullybroken in before attempting sustained high speed running.Patience and careful attention during break-in will reward you withthe best-performing TRX 2.5 possible.

    During break-in, your engine may appear to malfunction withsymptoms like stalling, inconsistent performance, and fouled glowplugs.These are simply the normal break-in pains enginessometimes go through.They will disappear once your engine isfully broken in. Many owners report not experiencing any of thesesymptoms with the TRX 2.5. We recommend to go ahead andreplace the glow plug with a new one after the engine break inprocedure.

    Engine Break-in ProcedureThe focus during break-in is to vary and limit the engine speed.This will be accomplished by accelerating and stopping at differentrates for the first 5 tanks of fuel. As the engine begins to break-in,the duration and intensity of the acceleration will graduallyincrease. Sustained high-speed running is not permitted until the6th tank of fuel. Perform the initial break-in on a large, flat, pavedsurface. Apply all throttle and braking actions gently. Abruptacceleration or braking could cause the engine to stallunnecessarily.

    Special break-in fuels are not recommended. Use the same fuelyou plan to use everyday.If possible, avoid breaking-in the engine on extremely hot orcold days.

    Pay careful attention to the fuel level. Do not allow the fuel tankto run completely empty. An extremely low fuel level causesthe mixture to run too lean.This could result in a burned glowplug or extremely high engine temperatures.Keep extra glow plugs handy (Traxxas part #3231).The break-inprocess can cause deposits to form on the plug leading to plugfailure.

    Follow the instructions exactly for each of the first 6 tanks of fuel.

    Starting Your TRX 2.5 Racing Engine for the First TimeBefore you start your TRX 2.5 engine for the first time, make sureyou have read all instructions and precautions in this manual. Payclose attention to the tank-by-tank break-in instructions in thenext section, and make sure you have read and understoodthem before you run your engine.

    Your engine must be at room temperature (70F or 21 C) orabove the first time you start it. If its cooler than roomtemperature outside, keep your T-Maxx indoors until youre readyto start it, then take it outside.

    1. Turn on the radio system according to the instructions on page18.

    2. Make sure the throttle is in the idle position.3. Connect the EZ-Start controller according to the instructions on

    page 31.4. Press the starter button and watch for fuel moving through the

    fuel line up to the carburetor.Watch closely! The fuel moves veryfast. If the fuel doesnt move through the line within 5 seconds,prime the engine by briefly (one or two seconds) covering theexhaust outlet until the fuel is just visible in the carburetor fuelline. Watch carefully! If the engine is primed too long, it willflood with fuel and stop turning.

    5. Once fuel reaches the carburetor, the engine should quickly startand idle.

    6. Disconnect the EZ-Start controller from the model.7. Proceed with the engine break-in.

    If your engine doesnt start, see Troubleshooting Your T-Maxxon page 42.

  • The TRX 2.5 Racing Engine

    33

    As you gainexperience in thehobby, you may

    discover that many peoplehave differing opinions onwhat is the properprocedure to break-in amodel engine. Only use theTraxxas break-in procedure.Other break-in procedurescould result in a weak,damaged, or otherwise poorperforming engine. Theprocedure outlined herewas extensively tested andproven to yield betterperforming engines thanother common break-inmethods. Even if you haveyears of experience usingmodel engines, please donot ignore this caution!

    Tank 11. Drive the model with the body off.2. Driving procedure: Gently pull the throttle trigger to 1/4

    throttle over a 2-second count. Then gently apply the brake tostop. Count the two seconds out while accelerating: onethousand one, one thousand two, and then stop. Operate thethrottle trigger as smoothly as you can. Repeat this starting andstopping procedure until the first tank of fuel is nearly empty.

    3. Look for thick blue smoke exiting the exhaust outlet. If there isno smoke, richen the high-speed needle 1/4 turn, by turning theneedle counterclockwise.

    4. When the fuel tank is nearly empty, shut off the engine bypinching the fuel line connected to the carburetor.

    5. Let the engine cool for 15 minutes.Note: If at any point the engine cuts out or stalls during gentleacceleration, richen the high-speed needle 1/4 turn by turning theneedle counterclockwise.

    Tank 21. From tank 2 forward, the T-Maxx should be driven with the

    body on.2. Driving procedure: Gently pull the throttle trigger to 1/2

    throttle over a 2-second count. Then gently apply the brake tostop. Count the two seconds out while accelerating: onethousand one, one thousand two, and then stop. Repeat thisstarting and stopping procedure until the second tank of fuelis nearly empty.

    3. When the fuel tank is nearly empty, shut off the engine and let itcool for 15 minutes.

    Tank 31. Driving procedure: Gently pull the throttle trigger to 1/2

    throttle over a 3-second count. Then gently apply the brake to stop. Count the three seconds out while accelerating: onethousand one, one thousand two, one thousand three,and then stop. Repeat this starting and stoppingprocedure until the third tank of fuel is nearly empty.

    2. As the engine loosens, the idle speed may increase and cause the model to try to creep forward whenstopped. Reduce the idle speed by turning the idleadjustment (see page 22) on the carburetorcounterclockwise.

    3. When the fuel tank is nearly empty, shut off the engine andrefuel. From here on out, you do not need to let the engine coolbetween tanks.

    Tank 41. Driving procedure: Gently pull the throttle trigger to full

    throttle over a 3-second count. Then gently apply the brake tostop. Count the three seconds out while accelerating: onethousand one, one thousand two, one thousand three, and thenstop. Repeat this starting and stopping procedure until thefourth tank of fuel is nearly empty.

    2. Apply the throttle gradually! Your finger should not reach fullthrottle until the end of the three-second count.The T-Maxx maytry to shift into second gear. If it does, reduce the throttle input.Do not let the T-Maxx shift out of first gear.

    3. Keep your driving smooth and consistent.4. When the fuel tank is nearly empty, shut off the engine and

    refuel.

    Tank 51. Driving procedure: Gently pull the throttle trigger to full

    throttle over a 3-second count, hold for 2 more seconds, andthen gently apply the brake to stop. Count the five seconds outwhile accelerating. Repeat this starting and stoppingprocedure until the fifth tank of fuel is nearly empty.

    2. The model should be shifting into second gear. If it is not, tryturning the high-speed needle clockwise 1/8 turn to lean thefuel mixture slightly and test for shifting.

    3. When the fuel tank is nearly empty, shut off the engine andrefuel.

    Tank 6During the sixth tank of fuel, the engine can be tuned for generalperformance use. Proceed to the next section in this manual.

    Tank12345

    Throttle1/41/21/2FullFull

    Time2 Seconds2 Seconds3 Seconds3 Seconds5 Seconds

    Cool15 Minutes15 Minutes

    ---

    BodyOffOnOnOnOn

    NotesApply throttle gradually.Apply throttle gradually.Reduce idle speed if necessary.Do not allow shifting to high gear.Accelerate over 3 second count,hold for 2 seconds.

  • 34

    The TRX 2.5 Racing Engine

    When adjusting thelow speed fuelmixture, it is very

    important to make severalhigh-speed runs with theT-Maxx betweenadjustments to clear out anyexcess fuel. Perform thepinch test immediately after.If the engine is allowed toidle for a long period of time,it could load up with fueland give you an inaccuratemeasurement from yourpinch test.

    For yourconvenience, thelow-speed needle

    has a positive stop thatprevents it from being overtightened and damaging theneedle and seat. This alsoprovides an easy way togauge how many turns outfrom closed the low-speedneedle adjustment is set to.

    When tuning forperformance, watchclosely to notice

    when there is no longer anyincrease in speed or powerwhen the high-speedmixture is lean. If you leanthe high-speed mixture tothe point that the enginecuts-out, hesitates, or stalls,you are well into the dangerzone and engine damage islikely. Richen the high-speedneedle 1/4 turn and retune.

    Tuning Your TRX 2.5 Engine for Best PerformanceThe engines performance depends on the fuel mixture. Turn themixture needles clockwise to lean the fuel mixture andcounterclockwise to richen it. Leaning the fuel mixture willincrease engine power up to the engines mechanical limits.Never run the engine too lean (not enough fuel flow). Neverlean the engine until it begins to cut-out or stall. Leaning theengine beyond the safe allowable limits will result in poorperformance and almost certain engine damage. Indicationsof an overly lean mixture include:

    Cutting out or sudden loss of power during acceleration. Overheating (temperature beyond 270 F at the glow plug)Little or no blue smoke coming from the exhaust.

    If any of these conditions are present, stop immediately andrichen the high speed mixture 1/4 turn. The engine willprobably be slightly rich at that setting and you can then retunefor performance. Always tune for performance by starting richand moving leaner toward the ideal setting. Never try to tunefrom the lean side. There should always be a light stream of bluesmoke coming from the exhaust.

    Before you begin tuning, the engine should be warmed up to itsnormal operating temperature and running slightly rich. All finaltuning adjustments must be made to the engine at its normaloperating temperature. You can tell the engine is running richby noting any of the following:

    Sluggish acceleration with blue smoke coming from the exhaust.The T-Maxx may not shift into second gearThere is unburned fuel spraying from the exhaust tipLeaning the high-speed fuel mixture increases performance

    High-Speed Fuel Mixture AdjustmentWith the engine warm and running at a rich setting, graduallylean the high-speed fuel mixture in 1/16 turn increments. Makeseveral high-speed passes with the T-Maxx after eachadjustment to clear out the engine and note any change inperformance. The TRX-2.5 is extremely powerful. Remember toapply the throttle gradually to prevent wheelies or loss of

    control. Continue this procedure until one of the followingconditions exist:

    1. There is no longer any performance improvement2. The engine begins to cut out at high speed (Danger!)3. There is a sudden loss of power during acceleration (Danger!)4. The engine begins to overheat. Symptoms of

    overheating include:

    Steam or smoke coming from the engine (not exhaust)Hesitation or stalling during accelerationPopping or clattering sound when decelerating(detonation)Fluctuating idle speedTemperature measurement above 270 F at the glow plug

    If any one of the above conditions occurs, the fuel mixture isalready past the maximum safe lean setting. Richen the fuelmixture to the optimum setting by richening the high-speedneedle at least 1/8 turn counterclockwise and retest. This settingwill extend engine component life.

  • The TRX 2.5 Racing Engine

    35

    Low-Speed Fuel Mixture AdjustmentThe low-speed mixture is always set after the high-speed needleis correctly adjusted. The low-speed mixture will be set using thepinch test.

    1. Once the engine is warm, do several high-speed runs toconfirm that the high-speed needle is set correctly.

    2. Bring the vehicle in and pinch closed the fuel line going intothe carburetor. The engine should run for 2-3 seconds, speedup, and then die.

    3. If the engine runs longer than 3 seconds, then lean thelow-speed needle 1/16 turn, make several more high-speed runs, and retest.

    4. If the engine dies immediately without speeding up, thenrichen the low-speed needle 1/8 turn, make several morehigh-speed runs, and retest.

    When the low-speed needle is set correctly, the engines throttleresponse should be very quick, possibly even to the point ofmaking it difficult to keep the T-Maxx from doing a wheeliewhen you accelerate!

    Idle Speed AdjustmentOnce the high and low-speed mixtures have been set, reducethe idle speed to the minimum reliable idle speed. Remember,this adjustment should be made while the engine is running atnormal operating temperature.

    1. Turn the throttle trim on the transmitter so that the brakesare applied. This ensures that the throttle slide is restingagainst the idle adjustment screw.

    2. If necessary, remove the air filter to gain access to the idleadjustment screw.

    3. Turn the screw counterclockwise to reduce the idlespeed, or clockwise to increase it. The idle speed shouldbe set as low as possible while still maintaining reliablerunning characteristics.

    4. Reset the throttle trim on the transmitter

    Note: If the idle speed is set too high it could prevent the T-Maxxfrom shifting between forward and reverse. If you experience this,simply reduce the idle speed.

    Fine-Tuning the CarburetorAfter fine-tuning your TRX 2.5 engine at the end of the break-inprocedure, no major adjustments to the fuel mixture are usuallynecessary. Make note of the temperature, humidity, andbarometric pressure at the time you finished fine tuning yourcarburetor. Current weather conditions can be found onlinefrom national websites, local TV news websites, and Television.This information will be considered your baseline setting.You may need to adjust your carburetor needles to compensatefor changes in temperature and barometric pressure (airdensity) from day to day. Generally, youll need to richen the fuelmixture when the weather is colder than your baselinetemperature and the air density is higher. Lean the fuel mixturewhen weather is warmer than your baseline temperature andthe air density is lower. The chart below provides generalguidelines on how weather conditions affect air density whenthey move higher or lower than your baseline setting (see page28 for detailed info on how air density affects mixture settings).

    If the...Humidity

    Pressure (barometer)

    Temperature

    Altitude

    Nitro %

    is..LowerHigherLowerHigherLowerHigherLowerHigherLowerHigher

    then the air density is...Slightly more denseSlightly less denseLess denseMore denseMore denseLess denseMore denseLess dense

    adjust (correct) the fuel mixture to be...Slightly richerSlightly leanerLeanerRicherRicherLeanerRicherLeanerLeanerRicher

  • 36

    Tuning The Engine By TemperatureThe following procedures require anoptional infrared temperature probeor on-board temperature gauge(Traxxas on-board digitaltemperature gauge, part#4090).Engine temperature can be used asan effective tuning aid when you understand the relationshipbetween engine temperature and ambient temperature.

    The engine operating temperature, when tuned for maximumperformance, will vary according to atmospheric conditions. Theatmospheric condition that has the most influence on enginetemperature is air temperature. Expect the engine temperatureto vary almost in direct proportion to atmospheric temperature.Assuming you tuned the engine for the same maximumperformance each day, the engine will run about twentydegrees hotter when its ninety degrees outside than it would inseventy-degree weather. For this reason, we cannot give you adefinitive temperature range that indicates the best possibleengine tuning.

    The temperature gauge can aid you in tuning by giving you arelative indication of how your adjustments are affecting theengine and by preventing you from exceeding maximumengine temperature. For example, as you lean the fuel mixture,the engine performance will increase along with thetemperature. If you continue to lean the fuel mixture and thetemperature increases but the engine performance does notchange, then you have exceeded the maximum safe leansetting.

    Even if its 100F outside, you should be able to tune formaximum performance. Try to keep your engine from exceeding270F when measured at the glow plug. If tuning for maximumperformance results in engine temperature exceeding 270F, tryto increase airflow tothe engine by cuttingout the rear of thebody, windshield, andfront valance. If theengine temperaturestill cannot be keptbelow 270F, richenthe high-speedneedle slightly.

    The TRX 2.5 Racing Engine

  • 37

    Driving the T-Maxx

    IntroductionYour TRX 2.5 engine is broken in,the fuel mixture is balanced, andthe idle is setnow its time tohave some fun! Thissection containsinstructions onforward/reverse shifting,and making adjustments toyour T-Maxx. Before you go on, here aresome important precautions to keep in mind.

    Dont run your T-Maxx in water, mud, snow, or wet grass.Its tempting, but water and mud are easily drawn throughthe air filter and will severely damage the engine. Smallamounts of moisture can cause electronics to fail and loss ofcontrol over your T-Maxx.The TRX 2.5 is extremely powerful. Remember to apply thethrottle gradually to prevent wheelies or loss of control.Dont hold the T-Maxx off the ground and rev the engineexcessively with no load on the engine. This practice couldresult in internal engine damage. Avoid over revving theengine when the T-Maxx is airborne after a jump.Avoid excessive high-speed running for extended periods oftime or over long distances. This could cause the engine tobuild up enough speed to exceed maximum safe RPM limits.Dont drive your T-Maxx with drive train damage of any kind.The engine could be damaged due to overloads on theengine caused by drivetrain friction, or over-revving causedby loose or missing parts.Dont tow anything with your T-Maxx. The engine is cooledby airflow created by speed. Towing creates a high load onthe engine, and at the same time limits cooling of the enginedue to low vehicle speed.If your T-Maxx gets stuck, stop driving immediately. Move thevehicle and then continue driving.

    Forward and Reverse OperationForward and reverse gearsare selected with the shiftbutton located in thetransmitter handle grip. Theswitch is normally in thedown, or forward, position.

    To shift into reverse,bring your T-Maxx to acomplete stop and pushthe shift button up.Accelerate to engage the gear.To return to forward gear, repeat the same procedure andmove the shift button down.The T-Maxx will not shift between forward and reverseunless the engine is at idle. If it will not shift, then refer to thetroubleshooting section on page 42.

    Driving TipsMonster trucks by design have a high center of gravity thatrequires a different driving technique. To prevent rollovers,slow down as you approach turns and then apply strongthrottle through the turns. This technique will help theT-Maxx grab the surface and turn sharper.Do not apply brakes and turn the wheel at the same time.You could tip the truck over.When jumping, apply some throttle while the T-Maxx is inthe air to keep the trucks nose up and land level on all 4wheels. Be careful not to over-rev the engine or land at fullthrottle. Either could seriously damage your T-Maxx. If thenose of the truck is too high, then quickly tap the brake tolevel the truck in the air..Drive over large obstacles (such as curbs and rocks) at anangle, instead of head on. This will allow the suspension toarticulate and absorb the impact much easier.Even though the T-Maxx is capable of full top speed inreverse, it is very difficult to control while driving in reverse.Limit your reverse speed to prevent crashing or flippingyour T-Maxx.

    SHIFTREVERSE

    SHIFTFORWARD

  • Once you become familiar with driving your T-Maxx, you mightneed to make adjustments for better driving performance.

    Adjusting the Slipper ClutchThe T-Maxx features an adjustable slipper clutch on the spurgear to help protect the drive train 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. Donot adjust the slipper clutch while the engine is running.

    Use the supplied glow plug (universal) wrench to tighten theslipper nut (clockwise) until it stops, and then back the nut out1/4 of a turn. If you notice any decrease in performance aftermaking changes to the slipper clutch adjustment, then it maybe too loose. The slipper must not be allowed to slip duringnormal acceleration or the slipper could be damaged.

    Adjusting the Two-Speed TransmissionThe T-Maxx comes equipped with a two-speed transmission.When the shift point on the transmission is adjusted correctly, itwill maximize acceleration and improve drivability. If necessary,use the supplied 2.0mm hex wrench to adjust the shift point.

    1. Stop the engine.2. Remove the large rubber plug from the transmission housing.3. Look into the hole in the

    transmission housingand rotate the spur gearuntil the access hole inthe aluminum drum is visible.

    4. Once the access hole isvisible, hold the spurgear and use your fingerto turn the primary gearshaft which extends from the transmission housing counter-clockwise. Note that you will see two set screws pass under

    the access hole. As you turn theprimary gear shaft counter-clockwise, the first set screwholds the two-speed mechanismto the shaft. Do not loosen thisscrew. The second set screw isthe adjustment screw.

    5. Insert the 2.0 hex wrenchthrough the clutch drum andinto the adjustment set screw.

    6. Turn the adjustment screw 1/8 turn clockwise to raise theshift point (later shifts). Be careful not to over tighten theadjustment screw or you may damage the tension spring.Do not make constantadjustments or you will loosenthe screws locking device.

    7. Turn the adjustment screw 1/8turn counter-clockwise to lowerthe shift point (earlier shifts).Be careful not to loosen theadjustment screw too much oryou may cause the screw andspring to fall out (requiring majordisassembly and repair).

    8. Use 1/8 turn increments to find the approximate, desired shift point.

    9. Check performance by running a test lap after each adjustment.

    10. Use 1/16 turn increments to fine-tune the shift point.11. Be sure to reinstall the access plug to prevent dirt from

    entering the transmission.HOLD

    38

    Adjusting Your T-Maxx

    Primary Gear Shaft

    (Viewed from front of truck.)

  • 39

    Adjusting the Toe-inYour T-Maxx comes from the factory with zero degrees of toe-inin the front, and one degree of toe-in in the rear.You can adjustthe toe-in on the front and rear of the truck. Set the steering trimon your transmitter to neutral. Now, adjust your steeringturnbuckles so that both front wheels are pointing straight aheadand are parallel to each other (0 degrees toe-in).This will ensurethe same amount of steering in both directions. Adjust the reartoe control links so that the rear wheels have 1 of toe-in.

    Adjusting the CamberTwo pivot balls are accessiblethrough the spokes of each of thewheels on your T-Maxx. From thefactory, the pivot balls arecompletely tightened into thesuspension arms, which give eachof the wheels 1 of camber.

    Unscrewing the bottom camber pivot ball with a 2.5mm hexwrench will increase the wheels negative camber. You shouldnot adjust the top pivot ball; unscrewing it will increase positivecamber and will also change the wheels toe-in.

    Fine Tuning the Oil DampersThe eight oil dampers (shocks) on yourT-Maxx have tremendous influence onits handling. Whenever you rebuild yourshocks, or make any changes to thepistons, springs or oil, always do itcarefully and in sets (front or rear).Piston head selection depends on therange of oil viscosities that you haveavailable. For example, using a two-holepiston with lightweight oil will give youthe same damping as a three-holepiston with heavier oil. We recommendusing two-hole pistons with a range ofoil viscosities from 10W to 40W(available from your hobby shop). Thethinner viscosity oils (30W or less) flowwith less resistance and provide lessdamping, while thicker oils providemore dampening. Use only 100% pure silicone shock oil toprolong seal life. From the factory, the T-Maxx uses 30W oil.

    The ride height for the T-Maxx can be adjusted by adding orremoving the clip-on spring pre-load spacers. Note that changesin ride height will occur when changes in shock angle or springrates are made. You can compensate for ride height changes bychanging the pre-load spacers on the shocks

    00

    11

    -1 -1

    Factory toe-insettings can beachieved by

    installing the rod ends onthe turnbuckles until theybottom out against theshoulder. If you desiremore toe-out, the tips ofthe rod ends must betrimmed to allow them toscrew down further ontothe turnbuckle threads.

    Adjusting Your T-Maxx

  • Adjusting Your T-Maxx

    Adjusting the suspensionThe T-Maxx has adjustable suspension so that it may beoptimized for different kinds of terrain and driving styles.

    Caster AdjustmentThe T-Maxx offers the ability to adjust the caster angle of thefront suspension. Caster adjustment may be used to influencethe understeer/oversteer handling characteristics of the T-Maxx.Increasing the caster angle will increase the tendency of thetruck to oversteer (less traction on the rear tires, more tractionon the front tires), while decreasing the caster angle will causethe truck to have a tendency to understeer (push in the turns).This effect becomes more pronounced at higher steering anglesand higher spring rates. Caster is adjusted by repositioning theshims on the pivot point of the upper suspension arms.The stock caster setting is 7-degrees with one shim at each endof the arm. Reduce the caster angle to 4-degrees by removingthe rear shim and inserting it next to the front shim. The casterangle can be increased to 10-degrees by removing the frontshim and inserting it next to the rear shim.

    Shock Mounting PositionsBig bumps and rough terrain require a softer suspension withthe maximum possible suspension travel and ride height.Racing on a prepared track or on-road use requires a lower rideheight and firmer, more progressive suspension settings. Themore progressive suspension settings help reduce body roll(increased roll stiffness), dive during braking, and squat duringacceleration.

    The innermost upper shock mounting position (0) on the shocktower is intended for use with the first generation T-Maxx

    suspension arms. With thesecond generation arms(2.5-powered T-Maxx),position (0) can be used fortuning with the inner pair oflower shock mountingpositions on the arm (1,2).It is not compatible withlower shock mountingpositions 3 and 4 on thesecond generation (2.5-powered T-Maxx) arms.Upper shock mountingposition (A) shouldgenerally be used withlower shock mountingpositions 1 and 2. Upper shock mounting position (B) should begenerally be used with lower shock mounting positions 3 and4.Other combinations may be used to achieve individualizedsuspension settings.

    Lower Shock Mounting Positions In the out-of-the-box configuration, the shocks are installed inposition (A) on the shock tower and position (2) on the lowersuspension arm. This setting allows for moderate suspensiontravel and ride height. The more vertical position of the shocksallows for lower shock progression and the soft, plush feel thatscharacteristic of the T-Maxx.The outer pair of holes on the lower suspension arm should beused to lower the ride height of the T-Maxx, and increase thespring force (at the wheel). This setting will improve high-speedcornering on smoother terrain by lowering the center of gravityand providing a firmer suspension feel. Body roll, brake dive, andsquat will be reduced.

    Spring rate (at the wheel) increases as the lower shockmounting position is moved from position (1) to position (4).This is equivalent to using stiffer springs. Use higher spring ratesettings for flatter terrain with smaller and fewer bumps, andlower spring rate settings for bigger bumps.

    40

    For easier access tothe rear-most shockmounting screw,

    remove the one end of therear turnbuckle. In the front,remove the suspension pinfrom the lower frontsuspension arm to gaineasier access to the lowershock mounting screws.

    7

    Caster adjustment shims (1 Front, 1 Rear)

    Vertical

    Ground plane

    Vertical4

    Caster adjustment shims (2 Front)

    Ground plane

    Vertical

    Caster adjustment shims (2 Rear)

    Ground plane10

  • Adjusting Your T-Maxx

    41

    Ride height decreases as the lower shock mounting position ismoved from position (1) to position (4). Each pair of lower shockmounting holes (1,2 and 3,4) has equal ride height. Use lowerride height for high-speed cornering and flat terrain, a


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