Jconcepts BJ4, Manual

BJ4 WORLDS EDITION SPECIFICATIONS 

Wheel 

Base:

10.94”   

(278mm) 

Vehicle 

Width:

9.65”   

(245mm) 

 Weight (ready to run): 

 3 lbs. 7.6 oz.  (1575g) 

Internal 

gear 

ratio:

2.50:1

 Front bulkhead kick-up: 

 8 degrees 

Front 

castor 

blocks:

10 

degrees

 Standard rear hub carrier toe-in: 

 0 degrees 

 Standard suspension mount toe-in:   

 3 degrees 

 Standard suspension mount anti-squat: 

  2 degrees 

FINAL ADJUSTMENTS 

Radio Adjustments: 

Use the following steps to make the final adjustments to your car: 

1.

Turn the transmitter on.

2.

Make sure the motor is disconnected.

3.

Connect your battery pack and turn the power switch on.

4.

Move the steering control on the transmitter to the right and left.  Do the wheels move in the correct
direction?  If not, you must reverse the steering servo direction on your transmitter (see radio
manual).

5.

Adjust your steering trim (see radio manual) until the steering bell cranks are centered under the
top deck.  Then, using the two steering turnbuckles, fine-tune the adjustment on the front wheels so
they are pointing straight ahead.  Check them once again when the car is race ready and the ride
height has been set.

6.

Adjust the ESC (electronic speed control) according to the speed control manufacturer’s
instructions.  

Some manufacturers have the motor connected during adjustment and some do not.

Now, turn the power switch off.

7.

Connect the motor.  Place your car on a block or car stand so that all four wheels are elevated.
Turn the power switch on again.  Check the ESC and steering settings you have made and then
turn the power switch back off.

8.

Remember this!  The transmitter is always the 

FIRST TO BE TURNED ON

 and 

THE LAST TO BE

TURNED OFF.

Advanced Radio Adjustments: 

Some radio systems offer dual rate and end point adjustments (see radio manual).  If your radio has 
these adjustments, adjust the dual rate to 100%.  Using the end point adjustments, adjust the left and 
right steering throw so the servo stops at the same point as the car’s physical steering stops.  If less 
steering is desired, reduce the dual rate adjustment in small increments. 

Advanced Speed Control Adjustments: 

Some speed controls offer drag brake (see speed control manual).  The drag brake adjustment can be 
use to automatically apply braking power when the driver lets off the throttle completely.   This adjustment 
can be used when the racing surface has enough traction that the driver feels comfortable allowing the 
speed control to automatically slow the car down when entering the turns.  This is a tricky adjustment that 
can work well when the traction is high enough.   However, it tends to unsettle the car and can lead to 
unpredictable responses. 

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