This R/C model assembly kit creates the 2 belt-driven 4WD TRF421, the latest model in the line of TRF chassis; its newly designed carbon fiber upper and lower decks move the motor 22.7mm further forward than on the TRF420X, while the center shaft is in the chassis center and drive belts are of equal size; pulleys are also a new design. The upshot of this is greater pitching stability on the throttle. Bulkheads have a new design for a lower center of gravity, and new USBB (ultra-short big bore) dampers are mounted via aluminum stays: they can be fine-tuned with spacers. The suspension uses upper and lower A-arms for superior rigidity, with identical lower arms front and rear that have a longer span for more linear roll that translates into more control.
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- The center shaft is moved into the middle of the chassis, and belts are of equal size, while pulleys are new: the result is less pitching on the throttle, and greater stability.
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- Front and rear bulkheads contribute to a lower center of gravity. Ultra-short big bore dampers are mounted via aluminum stays.
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- Front and rear bulkheads contribute to a lower center of gravity. Ultra-short big bore dampers are mounted via aluminum stays.
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- With the motor 22.7mm further forward than on the TRF420X, the center shaft is now in the chassis middle. The spur gear is affixed using a single nut for easier pit-work.
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- Stabilizers have had an overhaul, and now feature a common design front and rear, and are positioned lower than the drive shafts. The kit includes one each of 1.0mm and 1.2mm rods, and two 1.1mm parts.
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- The revamped suspension employs A-arms; lower arms are ball-attached. The lower pivot is positioned on the inside of the bulkhead to keep chassis width the same while allowing the long span lower arms. Lower arms have neutral toe on the inside, and toe angle is applied on the upright side.
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- 1-piece and 2-piece upper decks are included; use them to adjust flex. Using more or less screws to affix it to the motor mount lets you further fine-tune your setup.