OFNA Racing Ultra GTP MBX User Manual
1:8 SCALE NITRO POWERED TOURING CAR
RTR INSTRUCTION MANUAL
SAFETY PRECAUTIONS
!
This radio control models is not a toy!
- First time builders should seek the advice from people having building experience
in order to assemble the model correctly and to produce it's performance to full
extent.
- Assemble this kit and places out of children's reach!
- Take safety precautions while operating this model. You are responsible
for this models assembly and safe operation!
- Always keep this instruction manual ready at hand for quick reference, even after
completing the assembly.
*SPECIFICATIONS ARE SUBJECT TO CHANGE WITHOUT NOTICE.
REQUIRED FOR OPERATION
THINGS NEEDED
Glow Fuel
20%
AA Batteries ( 12 pcs )
#10211 NiHm Flat Pack
You will need to buy a few items to start the engine and run the car.
• Use 20% nitro CAR fuel. Do not use airplane or heli fuels, they will
over heat engine.
• Buy long glow plugs, like OFNA/PICCO Plug (#51007). Use plugs
without idle bar. Do NOT buy hot plugs, like the MC-59.
In your box you will find..
• #10163 - Bottle, spout top
• #10218 - Red “C” size glow heater
You need to get batteries for the radio transmitter and the car receiver
packs.
• Radio TX needs (8) eight AA batteries
• Car needs (4) four AA batteries.
Recommendation Option:
You may want to upgrade the car battery pack to a Ni-Cad or NiHm 5
cell type(600AE). This will give more run time. OFNA #10211
1000NiMh Flat Pack and NiHm Battery Charger #10214
TOOLS NOT INCLUDED IN KIT
Phillips Type Screw Drivers ( L )
Phillips Type Screw Drivers ( S )
Needle Nose Pliers
Knife
Instant Cement
Cutter
Curved Scissors
Masking Tape
Brush
Cross Wrench
#17109 $3.95
Paints
Glow Plug & 17MM Cross Wrench
#10801 $6.95
Grease
READ THIS BEFORE RUNNING
Running a nitro kit is fun and easy, but to make this a safe rusting.
and good experience you must observe a few rules. This
kit is extremely fast, easily over 40MPH, and can seriously
injure someone if you are not careful.
Where to run car?
• Any running area you choose must be dry. Do not run
car near any water or wet dirt.
• Do not run on public streets. It is very easy to have the
car run over or damaged by hitting the curb.
• Do not operate car in tight confined places. The car is
very fast and will easily hit something.
• Do not run near people or animals.
and will too easily hit someone.
• Due noise, you will want to consider the surrounding
area when operating the car.
• Do not operate the car at night. You will not be able to
drive it without hitting something.
• Do not operate the car indoors. Engine exhaust is not
healthy.
Glow Fuel
• Glow fuel is poisonous!
• Glow fuel is flammable!
• Do not leave in fuel bottle with lid off at any time. label for additional precautions.
• Don use any fuel other than glow fuel in this engine.
First Time Starting the Engine
Caution! When starting engine make sure the following is
observed. • Always turn off the car BEFORE turning off radio.
• Set engine Master needle to 3 turns (rich setting)
• Do not do this alone, get an experienced friend to help at • DAMAGE DUE CAR RUN AWAY IS NOT A WARRANTY
first. ISSUE.
• Fill fuel tank, try not to spill fuel. Do not spill fuel on
receiver
• Hold car off the ground, so it will not runaway when first
starts
• Turn on Radio and check the linkage before starting
engine.
• Turn on car receiver battery switch.
• Always have an air filter on the carburetor to keep dirt
out.
The car is very fast
• Clear oil and dirt from chassis with a degreaser.
Precautions
• This kit is not a toy. Always run car with a second
person as a spotter and pitman.
• Hot Parts - The pipe, manifold, engine and head are very
hot and will cause burns.
• Rotating Parts - Keep hands away from the drive train,
wheels, and engine when engine is running.
• Radio - Check batteries life before running the car. If
radio does not have full control of the car with steering
and/or throttle/brake do not run until corrected. Failure to
correct this will result in possible injury and damage to the
car or property.
• Glow fuel - Do leave the glow fuel unattended with the lid
off. Fuel contains Methanol and Nitro Methane and is
flammable and poisonous.
Store fuel in cool ventilated location. Refer the glow fuel
• Car Fuel tank - Never store fuel in car tank, it will ruin the
engine if left in tank.
IF YOU DO NOT BREAK-IN ENGINE
CORRECTLY, MAINLY AT LOW RPM,
YOU WILL BREAK THE CONNECTING
ROD!
Engine Break-in
• See Engine Page.
Emergency Stopping Engine When Running
• Remove air filter and cover carb. intake.
• Squeeze fuel line and hold until engine stops.
• With a rag, cover exhaust outlet.
Storing Car After Running
• Remove fuel from tank and fuel lines
• Turn off radio in car
• Put a few drops of after run in engine to keep it from
FAILURE TO NOT READ AND
FOLLOW BREAK-IN ENGINE
INSTRUCTIONS WILL VOID
WARRANTY!
ASSEMBLY OF THE THROTTLE LINKAGE SYSTEM
#30800
Plastic Throttle
kit
Throttle
Spring
Plastic Collar
* Take the plastic collar
from brake system plastic
parts.
3X3mm
Set Screw
#30530
Plastic Throttle
Ball Joint
2mm Rod
3X3mm
Set Screw
#10300
Alum.Stopper
Place battery pack in a plastic bag before
securely tie wrap pack to radio plate. Pack
will fall out if not securely mounted! Check
the battery pack if you have any radio
interference, don’t run car if you see a
problem..
* Snap On.
Brake
Idle Position
Full Throttle
3X3mm
Set Screw
#10300
Fuel
Tube
( 6mm )
Alum.Stopper
* Align throttle servo same
as shown.
CHECKING ENGINE THROTTLE
A
1. Insert AA batteries into
transmitter (8 Pcs).
2.Turn on transmitter.
3.Turn on receiver.
4.Center throttle trims as
shown .
IMPORTANT
CHECK RADIO THROTTLE
AND STEERING SWITCHES
BEFORE RUNNING CAR
* Insert into transmitter.
1. Pull Full Throttle.
B
C
1. Push trigger to full
brake position.
2. Adjust alum. Stopper to
increase or decrease
the brake.
B
A
* Align throttle servo same
as shown.
Brake (C)
A
Idle Position (A)
Full Throttle (B)
• Full throttle arm position.
Spring rod pulls throttle
barrel open and brake
rods release pressure on
brake cams.
C
B
C
• Full brake arm position.
Spring compresses
forward and brake rods
pull brake levers.
SHOCK ASSEMBLY
1mm
Washer
2mm
Washer
32237
Rebuild
7mm
E-Ring
* Note the E-Ring must
fit into groove as shown.
Kit
* Fit into groove.
Oil Seal
32203
Dust Pusher, Short
(Yellow Rubber)
32205
Dust & Shaft
Protector, long
*Push onto shock
cylinder.
32292
Front. 3.5mm
Short Shaft
Shock Shaft
* Short shaft
for front.
2.6 x 5mm
Washer
* Assembly 4 pieces of the
shock shaft .
30671
Front Shaft, 3.5mm
with Piston
Piston
2.6mm Nut
Scre
Ce
men
w
t
32051
E-Ring
6mm Ball End
( Make 2 for front.)
( Make 2 for rear. )
32051
6mm Ball End
FILLING THE SHOCKS WITH OIL
1. Pull down piston and pour oil into
shock cylinder. Remove air bubbles
by slowly moving piston up and down.
Silicone
Oil
2. Pull down piston, attach pressure top
and shock oil overflow with tissue
paper.
*Leave 3mm.
32043
Cap, blue
32236
Rear, 3.5mm
Long Shaft
3. Tighten up shock cap.
* Long shaft
for rear.
30672
Rear Shaft, 3.5mm
with Piston
* Be careful not to damage shock shaft.
* Screw down cap.
UP
down.
*Move Slowly.
ASSEMBLY OF THE SPRING
Spring Holder
30403
6mm
Ball Joint
* Push 6mm ball joint
into ball end.
32300
Front, Spring Pair, GTP
32301
Rear, Spring Pair, GTP
32033
Pressure Top
Fit into groove.
*
32051
Misc. Plastic Shock Parts
*Slide spring collar into Shock.
Spring Collar
32051
Misc. Plastic Shock Parts
(Standard)
1mm
3mm
5mm
*Spring Tension adjust .er
ASSEMBLY OF NEW “K” STYLE DIFFERENTIAL CASE AND GEARS
31324 - FRONT OR REAR DIFF UNIT
31325 - CENTER DIFF UNIT
30779
2 x 12.8mm
Pin
* Position the O-ring
as shown.
30751 Diff. Case ( Front/Rear )
30761 Diff. Case (Center )
30779
2 x 12.8mm
Pin
30771
Diff. Shaft
30779
P5 O-Ring
( Orange )
30779
0.5 x 26mm
O-Ring
30769
Diff. Bevel Gear
( Large )
30779
4 x 10mm
Washer
* Apply diff. Gear grease to the
differential, during assembly.
* Fill the diff. Case to
approx 70% with grease.
Grease
30769
Diff.
Bevel Gear
( Small )
30773
4mm
Cross Pin
30769
Diff.
Bevel Gear
( Small )
30773
4mm
Cross Pin
30779
4 x 10mm
Washer
30769
Diff.
Bevel Gear
( Small )
30779
4 x 10mm
Washer
NB. It is very important to remove
the 30779 shim if the mesh
is too tight.
30771
Diff. Shaft
30769
Diff.
Bevel Gear
( Large )
ASSEMBLY OF THE BEVEL GEAR
( Builds two differentials for front and rear. )
30120
Bevel Gear
(Large/Metal)
31010
Optional - Bevel Gear
(Harden Steel)
30121
3mm
Tube
30779
P5 O-Ring
( Orange )
30121
3 x 5mm
Screw
30751 Diff. Case ( Front/Rear )
30761 Diff. Case (Center )
Sc
rew
Ce
me
nt
36730
Cap Joint
90026
5 x 5mm
Set Screw
30620
7 x 19mm
Bal lbearings
90026
5 x 5mm
Set Screw
3x10mm
Tapping Screw
3x10mm
Tapping Screw
Scre
Cem
w
t
en
* Push 3mm tubes into
holes of the diff. Case.
* Notice the straight holes
are for front and rear.
30121
3mm
Tube
30121
3 x 5mm
Screw
(Small Head)
5 x 5mm
Set Screw
3 x 5mm
Screw
30620
7 x 19mm
Ball bearings
36730
Cap Joint
ASSEMBLY OF THE SPUR GEAR
(Solid Center Drive)
33020
Center Gear
Shaft
30170
Brake Joint, Drive Cup
Screw
Cement
30201
90026
5 X 5mm
Set Screw
Center
Diff. Mount
33020
Center Gear
Mount
7 x 19x 5mm
Ball Bearings
90026
5 X 5mm
Set Screw
30110
Spur Gear
7 x 19x 5mm
Ball Bearings
30201
Center
Diff. Mount
ew
Scr
ement
C
3 x 10mm
Screw
90026
5 X 5mm
Set Screw
30170
Brake Joint, Drive Cup
ASSEMBLY OF THE CENTER PLATE
1
30201
* Apply instant cement to
glue brake pad and packing.
(Rear)
36660
Brake Pad
36661
Brake Pad
Packing
(Front)
Center
Diff. Mount
(Front)
3
3 x 3mm
Set Screw
Scr
Cem
ew
ent
36650
Brake Disc
(Steel)
Leave 0.5mm
3x12mm
Screw
2
3 x 10mm
Tapping Screw
30652
Center Plate
30211
Plastic
Bearing
or
30212
Flange Ball
Bearing, option
30213
Brake Cam
30171
Brake Lever
ASSEMBLY OF THE GEAR BOX
( Assemble two gear boxes for front and rear. )
30010
1
30630
6 x 13 x 5mm
Ball Bearing
* Insert two ball bearings
as shown.
3
Gear Box
30010
Gear Box
Screw
Cement
36730
Cap Joint
30630
6 x 13 x 5mm
Ball Bearing
2
5 x 5mm
Set Screw
* Make two gear boxes for front and
rear.
* Place set screw in D cut.
30130
Bevel Gear
4 x 20mm Flat Head
Tapping Screw
Front Diff. Assembly
ASSEMBLY OF THE FRONT SHOCK TOWER
4 x 10mm
Tapping Screw
4 x 10mm
Tapping Screw
30010
Gear Box
Cover
34008
Front Shock Tower,GTP
4 x 20mm
Flat Head
Tapping Screw
* Insert the stabilizer before
assembly th shock stay.
30340
Stabilizer Bar
ASSEMBLY OF THE FRONT ARM HOLDER
3 x 20mm
Flat Head
Tapping Screw
1
0
4 x 15mm
Tapping Screw
( Small Head )
1
0
4x10mm
Tapping Screw
4 x 15mm
Tapping Screw
( Small Head )
30160
Front Lower
Arm Holder
ASSEMBLY OF THE FRONT
PIVOT BALL KNUCKLE ARM
* Use 5mm
hex wrench.
36904
14mm
Alum. Nut
36903
13.8mm
Steering Ball
36905
Steering Ball
Washer
36901
Ball Type
Knuckle Arm
( Right and Left )
R
* Note the "R" mark
is for righthand side.
36053
8x16mm
Ball Bearing
4 x 10mm
Tapping Screw
( Small Head )
Assembly of the right and left hand side
are the same.
* Adjust alum. Nut to
keep steering ball
smoot.
R
8mm
Axle
36053
8x16mm
Ball Bearing
36052
CVA
Constant Velocity Axle
ASSEMBLY OF THE FRONT KNUCKLE ARM
INTO FRONT ARM
4 x 10 mm
Set Screw
36055
2.5 x 17mm
36054
Wheel Hub
( Alum. )
Pin
* Use 2.5mm
Hex Wrench.
R
36900
Front
Upper Arm
36890
Front
Lower Arm
Assembly of the right and left hand side
are the same.
* A 4 x 10mm set screw is used
to adjust the ride height.
36870
4x4mm
Set Screw
3mm
3.5mm
* Approx 3mm.
ASSEMBLY OF THE FRONT ARM ONTO GEAR BOX
3 x 20mm
Cap Screw
5 x 5mm
Set Screw
3 mm E-Ring
M3 Flange Nut
( Steel )
5x5mm
Set Screw
* Do not over tighten
5x5mm set screw.
RR
* Insert drive shaft
before assembly.
3mm
E-Ring
3x25mm
Cap Screw
Assembly of the right and left hand side
are the same.
S
3mm
C
cre
e
m
Flange Nut
w
ent
1
0
30151
Lower Arm Shaft
3mm
E-Ring
90021
3mm
E-Ring
RR
ASSEMBLY OF THE CASTER ADJUSTER
36905
Caster Angle
Adjuster
3 x 3mm Set Screw
3 mm E-Ring
30152
3mm
E-Ring
Upper arm Shaft
Caster angle will
become bigger.
* o change
use adjuster t
the caster angle .
Caster angle will
become less.
1
0
1
0
ASSEMBLY OF THE REAR SHOCK TOWER
34009
Rear Shock
Tower, GTP & WII
30340
Stabilizer Bar
3 x 20mm
Flat Head
Screw
* Insert stabilizer before
assembly of the shock tower
3mm
E-Ring
* A 4 x 10mm set screw is used
to adjust the ride height.
* Approx 3mm.
30151
Arm Shaft
(Long)
4 X 10mm
Set Screw
M3
Nylon
Lock Nut
M3
Nylon
Lock Nut
* Don't over tighten tapping screw.
30351
Rear Lower Arm
Holder
Assembly of the right and left hand side
are the same.
3 x 15mm
Screw
4x16mm
Flat Head
Tapping Screw
36030
Rear Lower
Arms
1
Degree
Fig.1
1.5
Degree
3mm
E-Ring
30350
Rear Wheel
Toe-in Cams
* Set triangle marks in
the direction shown
in Fig.1.
3mm
E-Ring
ASSEMBLY OF THE REAR HUB
36081
Rear Hub
* Builds two upper Rods for left and right side.
36880
5x60mm
Turnbuckle
36053
8 x 16 x 5
Ball Bearings
36053
8 x 16 x 5
Ball Bearings
36055
2.5 x 17mm
Pin
36054
Wheel Hub
( Alum. )
Assembly of the right and left hand side
are the same.
ASSEMBLY OF THE REAR DRIVE SHAFT
36082
Rear Wheel
Axle Shaft
36690
7mm Plastic
Arm Ball End
36850
7mm Ball
36690
7mm Plastic
Arm Ball End
* Anticlockwise mark.
42mm
0 10 20 30 40 50
Assembly of the right and left hand side
are the same.
mm
90020
2.5mm
E-Ring
5x5mm
Set Screw
* Do not r tighten
5x5mm set screw over tighten.
* Insert rear drive shaft
befor assembly.
36110
Rear Drive
Shaft
36170
3mm
Rear Arm Shaft
90020
2.5mm
E-Ring
ASSEMBLY OF THE REAR UPPER ARM ROD
M3
3 x 20mm
Cap Screw
3 X 25mm Cap Screw
3mm
Nylon Lock Nut
3mm
Nylon Lock
Nut
* Insert into rear hub.
Nylon
Lock Nut
3 x 20mm
Cap Screw
Assembly of the right and left hand side
are the same.
t
t
en
en
ew
ew
cr
cr
S
S
Cem
Cem
3mm
Flange Nut
ASSEMBLY OF THE REAR STABILIZER ROD
30401
6mm
Stabilizer
Ball End
30402
3 X 30mm
30401
6mm
Stabilizer
Ball End
30403
6mm
Ball Joint
Tie Rod
3 x 3mm
Set Screw
3 x 15mm
Screw
3 x 25mm
Cap Screw
15mm
0 10 20 30 40 50
mm
w
re
Sc
Cement
30340
6mm
Stabilizer
Ball End
* Insert the stabilizer rod into arms
before assembly.
3 x 15mm
Screw
3 x 15mm Screw
ASSEMBLY OF THE SERVO SAVER
(36740 Servo Saver Plastic parts)
36743
6mm
E-Ring
36740
Servo Saver
Horn B
36741
Servo Saver
Spring
36740
Servo Saver
Horn A
36743
6mm
E-Ring
36740
Servo Saver
Top Adapter
36740
Servo Saver
Horn B
3 x 15mm
Screw
36742
Servo Saver
Bushing
36742
Servo Saver
Bushing
36740
Servo Saver
Shaft
(Brass)
36743
6mm
E-Ring
Plastic Tube
36743
6mm
E-Ring
36741
8x12mm
Washer
36740
Servo Saver
Shaft
(Brass)
ASSEMBLY OF THE FRONT PLATE AND
STEERING ROD
3 X 10mm
Screw
30540
Front Plate
30410
6mm
Ball & Socket
3mm
Nylon Lock Nut
M3 Nylon Locknut
3 x 15mm Screw
6 mm E-Ring
3mm
Nylon Lock Nut
36750
Servo Saver
Connector
* Made two steering rods for left and right-side.
30410
6mm Steering
30400
3 x 46mm
Turnbuckle
30410
6mm Steering
Ball End
Ball End
30410
6mm
Ball & Socket
30380
Servo Saver
Post
* Anticlockwise mark.
( Left-Side )
35mm
( Right-Side)
35mm
0 10 20 30 40 50
mm
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