OFNA Racing Ultra MBX Comp User Manual

INSTRUCTION MANUAL

Ultra MBX Comp Rev:01

REQUIRED FOR OPERATION

THINGS NEEDED

Glow Fuel

20%

AA Batteries ( 12 pcs )

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 51009 for auto start. Use plugs without
idle bar. Do NOT use plugs, like the MC-59 or OS-8 or any short plug

In your box you will find..

• #10162 - Bottle, 250cc

You need to get batteries for the radio transmitter and the car receiver packs.

7.2 volt pack for power start

• Radio TX needs (8) eight AA batteries.

• Car needs (4) four AA Ni-cad batteries, Alkaline type batteries will work, but
braking will be reduced. The best is to use a 5 cell hump pack for increased
voltage..

Recommended 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 #10212 1000NiMh Hump

10214
recv
pack

#10212 NiHm Hump Pack,
see charger 10214.

TOOLS NOT INCLUDED IN KIT,
BUT NEEDED TO MAINTAIN YOUR CAR.

Phillips Type Screw Drivers ( L )

Phillips Type Screw Drivers ( S )

10195
Battey
pack

7.2

Cutter

91009
Curved Scissors
$5.95

Cross Wrench
#17109 $3.95
#10796 $3.95

10239
Instant Cement

10620
Diff Gear
Grease
$9.95

Needle Nose Pliers

Knife

Glow Plug & 17MM Cross Wrench
#10801 $6.95

MUST 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.

• Do not 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.

Engine Break-in

• See Engine Page.

The car is very fast

• Clean 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!

FAILURE TO NOT READ AND
FOLLOW BREAK-IN ENGINE

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

INSTRUCTIONS WILL VOID
WARRANTY!

CHECK RADIO SETTING AND
LINKAGE BEFORE STARTING

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

2mm Rod

3X3mm
Set Screw

Plastic Throttle
Ball Joint

* Snap On.

#10300
Alum.Stopper

Note:

Battery life is short when using Alkaline batteries. For safety, we recommend using
Alkaline batteries for only 30 minutes before testing; mostly changing. Battery strength
affects braking power and radio range. If voltage drops while running the car, you will
loose control and destroy your car! This is NOT covered under warranty.

To increase run time, upgrade receiver battery to a 5-cell hump pack. Also, install a
battery fail safe (OFNA # 91002) to further protect your car. But, the most important step
you can make, “is to always use fully charged or fresh batteries when running your car”.

Brake

Idle Position

Full Throttle

3X3mm
Set Screw

#10300
Alum.Stopper

Fuel
Tube
( 6mm )

* 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

C

Radio shown, may be
different from what is in
your kit. OFNA
reserves the right to
change upon stock
availability.

B

• Full brake arm position.
Spring compresses
forward and brake rods
pull brake levers.

ASSEMBLY OF THE FRONT AND REAR DIFFERENTIAL

Step 1

*Builds two differentials for
font and rear.

*Notice the straight
holes are for the
front and rear only.

30620
7x19x6mm
Ball bearings

30779
2x12.8

30779
P5
O-Ring

30769
Diff. Gear
(Large)

30773
4x27mm
Cross Pin

30779
2x12.8mm

30779
4x10mm Washer

30779
P5 O-Ring

94034
Set Screw

X2

X2

X4

X2

X2

Step 2

30779

0.5x26mm
O-Ring

30901
Cap Joint

30779
P5
O-Ring

30751(Front/Rear)
30761(Center)
Diff. Case

30769
Diff. Gear
(Large)

30620
x19x6mm
Ball bearings

30779
2x12.8

94034
Set Screw

30751(Fro nt/Rear)
30761(Center)
Diff. Case

30901
Cap Joint

ASSEMBLY OF THE DIFFERENTIAL GEAR

94004
3X12mm
Hex Screw

X4

30779
4x10mm
Washer

30769
Diff. Gear
(Small)

30773
4mm
Cross Pin

30769
Diff. Gear
(Small)

30779
4x10mm
Washer

30779
4x10mm
Washer

30769
Diff. Gear
(Small)

30773
4mm
Cross Pin

* Put the differential gears
same as picture shown.

30769
Diff. Gear
(Small)

30779
4x10mm
Washer

94004
3X12mm
Hex Screw

*Apply diff. Gear grease
to the differential, during
assembly.
*Fill the dif. Case to
approx 80% with grease

ASSEMBLY OF THE CENTER DIFFERENTIAL

30773
4x27mm
Cross Pin

X2

Step 1

30911
Break Cap Joint

*Notice the tapered
holes are for the
center differential only.

30620
7x19x6mm
Ball bearings

30779
P5
O-Ring

30769
Diff. Gear
(Large)

30779
2x12.8

30761(center)
30751(F/R)
Diff. Case

30779
2x12.8mm

30779
4x10mm Washer

30779
P5 O-Ring

94034
Set Screw

X2

X4

X2

X1

Step 2

30779

0.5x26mm
O-Ring
O«¬Àô

ASSEMBLY OF THE DIFFERENTIAL GEAR

94004
3X12mm
Hex Screw

X4

30779
4x10mm
Washer

30779
P5
O-Ring

30779
4x10mm
Washer

30769
Diff. Gear
(Small)

30761(Center)
30751(F/R)
Diff. Case

30769
Diff. Gear
(Large)

* Put the differential gears
same as picture shown.

30620
7x19x6mm
Ball bearings

30779
2x12.8

94034
Set Screw

30911
Break Cap Joint

94004
3X12mm
Hex Screw

30769
Diff. Gear
(Small)

30773
4mm
Cross Pin

30769
Diff. Gear
(Small)

30779
4x10mm
Washer

30773
4mm
Cross Pin

30769
Diff. Gear
(Small)

30779
4x10mm
Washer

*Apply diff. Gear grease
to the differential, during
assembly.
*Fill the dif. Case to
approx 80% with grease

ASSEMBLY OF THE SPUR GEAR

30111
3x10mm
Flat Head Hex Screw

35313
M3 Nylon Nut

94033
M3x3 Set Screw

X4

X4

X4

30111
3x10mm
Flat Head
Hex Screw

*Notice the tapered
holes are for the
center diff. Only.

31040
51T Spur Gear

Center differential
assembly

35313
Nylon Nut

* The picture show are
center differential after
assembly.

30201
Center Diff. Mount
(Front)

Note
the holes for the rear
diff. Mount are wider

30201
Center Diff. Mount
(Rear)

* Note:
the holes for the rear
diff. Mount are closer .together

ASSEMBLY OF THE BRAKE CAM

94033
M3x3
Set Screw

30171
Brake Lever

30213
Brake Cam

ASSEMBLY OF THE BRAKE CAM AND BRAKE PADS

ASSEMBLY OF THE BRAKE CAM AND CENTER PLATE

30213
Brake Cam

94004
3X12mm
Hex Screw

30652
Center Diff.
Plate

30211
Plastic Bushing
30212
Ball Bearing

94004
3X12mm Hex Screw

30211
5x8x2.5mm
Plastic Bushing

94033
M3x3 Set Screw

X2

X2

X4

30171
Brake Lever

ASSEMBLY OF THE BRAKE PADS

94033
M3x3
Set Screw

30211
Plastic Bushing
30212
Ball Bearing

Note:

94005
3X15mm
Hex Screw

3mm

*Leave 3mm gap
between the brake cam
and nut.

94005
3X15mm Hex Screw

94005
3X15mm
Screw

X4

0.5mm

*Leave a 0.5mm space
between brake disk and
brake pad.

94005
3X15mm
Screw

36650
Brake Disk
Steel

36650
Brake Disk
Steel

* Remove the double-side tape
before assembly.

36661
Brake Pad
Linings

36660
Brake Pad

ASSEMBLY OF THE FRONT BEVEL GEARS

*Push 3mm tubes into the
holes of the diff. Case.

30120
Bevel Gear
(Large / Metal)

30121
4x3x3mm
Chromed Tube

3x5mm Hex Screw

X4

X430121

30121
3x4x4mm
Chromed Tube

ASSEMBLY OF THE FRONT GEAR BOX

94036
M5x5 Set Screw

94010
4x12mmHex Screw

Step 1

X1

X2

30010
Gear Box

94036
5x5mm
Set screw

30121
3x5mm
Hex Screw

30630
6x13x5mm
Ball Bearing

30130
Bevel Gear
(Small)

* Builds two differential for
front and rear.

Step 2

94010
4x12mm
Hex Screw

94009
4x10mm
Hex Screw

94022
3x18mm
Flat Head Hex Screw

94029
4x25mm
TP Flat Head
Hex Screw

90018
3X25mm
Cap Screw

94011
4X15mm
Hex Screw

94003
3X10mm
Hex Screw

30010
Gear Box
Front Cover

94022
3x18mm
Flat Head
Hex Screw

X2

X2

X2

X2

X2

X1

94009
4x10mm
Hex Screw

* Place 5x5mm
set screw in d cut.

Step 3

34018
Shock Tower

36730
Cap Joint

30630
6x13x5mm
Ball Bearing

Step 4

36610
Shock Support
Steel

36507
Shock Support
Alum

94003
3X10mm
Hex Screw

90018
3X25mm
Cap Screw

34021
Front Upper Arm
Holder

30102
Front body
Post

94029
4x25mm
Flat Head Hex Screw

* Notice the direction.

94011
4X15mm
Hex Screw

30160
Front Lower
Arm Holder

ASSEMBLY OF THE CVD DUST COVER

*Made two CVD joint.

10189
CVD Dust Cover

ASSEMBLY OF THE KNUCKLE ARMS

Assembly of the right and left hand side
are the same.

40105
CVD Joint

40105
CVD Joint

36901
Ball type
Knuckle Arm(Left)

* "L" mark for left side.

36055

2.5x16.8mm Pin

90026

5x4mm Set Screw

X2

X2

ASSEMBLY OF THE KNUCKLE ARMS

Assembly of the right and left hand side
are the same.

36903
14mm
Steering Ball

36053
8x16x5mm
Ball Bearing

Make steering
ball move
smooth.

Make steering
ball move
smooth.

36905
Plastic Washer

36053
8x16x5mm
Ball Bearing

36904
14mm
Alu m. Nut

36054
Wheel Hub

36055

2.5x16.8mm Pin

90026

5x4mm
Set Screw

36903
14mm
Steering Ball

36905
Plastic Washer

36904
14mm
Alu m. Nut

ASSEMBLY OF THE FRONT ARMS

30151
4mm Arm Shaft

36170
3mm Arm Shaft

Assembly of the right and left hand side
are the same.

X2

X2

3mm E-Ring

2.5mm E-Ring

36881
Front Upper Arm

X4

X4

*Approx. 2.6mm

*Approx. 3mm

90020

2.5mm
E-Ring

36170
3mm Upper
Arm Shaft

36881

Front Lower Arm

90021

3mm
E-Ring

90020

2.5mm
E-Ring

30151

90021

3mm
E-Ring

CLIP IN THE CASTER ADJUSTER

36905
Caster Adjuster

* o change

use adjuster t

the caster angle .

Caster Adjuster

Caster Adjuster

ASSEMBLY OF THE FRONT STABILIZER

94002

3x8mm Screw

3x8x0.8mm
Washer

94006

3x18mm Screw

94035

M3x8mm Set Screw

X2

X2

X2

X2

34027
Stabilizer

94002

3x8mm
Screw

3x8x0.8mm
Washer

Caster Adjuster

*Caster angle will
become bigger.

Assembly of the right and left hand side
are the same.

* Cut the plastic as shown.

*Caster angle will
become less.

A

B

94033

M3x3 Set Screw

Assembly of the right and left hand side
are the same.

X2

94033

M3x3
Set Screw

94006

3x18mm
Screw

40199
Stabilizer
Ball End

94035

M3x8mm
Set Screw

40199
Stabilizer
Ball End

30341
Stabilizer Ball

30403
6mm Ball