TT-01 Type E Chassis The bathtub frame of the evolved shaft-driven 4WD TT-01 Type-E has its motor and battery close to the ground for lower center of gravity and optimum balance. Mounted on the bathtub frame are a fiberglass reinforced nylon upper deck and gear covers which improve rigidity, as well as a 3-piece tie rod to provide smooth steering action. The low center of gravity, great balanced design, 4-wheel double wishbone suspension system, and front and rear differential gears all come together to result in superb driving characteristics.