jerky start
 

can anyone tell mi y does my car jerks when i accel all out from the start? but it rolls out smoothly under light acceleration.

when i first had the stock 540 motor, the car would juz jerk once and then take off smoothly when i accel all out.

however, after i change the motor to a Tamiya Stock T (23 turns), the car would juz keep on jerking all the way when i accel hard. :(

i also noticed that the drive train isnt very smooth. when i tried to turn the spur gear by hand, the drive train kind of jerks like when i accel all out.

You need to go through the car, disassemble the drivetrain and reassemble it making sure everything goes smoothly. Your drivetrain should not be bound up.

Jerking starts
 

The "Jerking" may be the brushes on your motor arcing and causing a glitch.
When you turn the drivetrain over by hand the magnets in the motor will cause a "Cogging" effect to be felt.
Make sure the Com and brushes in you motor are in good shape.

found out the prob
 

thanks for the suggestion guys. finally found out wats the problem. it seems like the esc(an Xpress England 250HF. got it cheap for less than US$15 2nd hand) i was using was not set up and when i throttle all out, it seems to pass the limitation of the esc causing it to jerk. I using a cheapo tx that offers not much function. finally set the esc up last nite and the car was ready to roll.

cheers

Good Troubleshooting
 

Glad you found the problem.

you should also check your speedo and wiring .. if there is a bad connection then it will cause issues like that. it can also lead to a burned car