[JERRY2KONE]

Engineering wise that is somewhat natural due to the torsional twisting effect of the motor because it is mounted from front to rear in the vehicle. It should not be too noticable though being that the vehicle is pretty small. In 1:1 dragsters it can actually throw the car into the wall due to this physical act of mechanical nature if it is not compensated for. It sounds to me like since you shimmed the diff properly you have a very tight setup that is near perfect, casuing the vehicel to pull to one side.