年初的德國紐倫堡玩具展，Tamiya田宮模型TRF421新一代競賽級電動房車首次亮相，目前相信這款新車已經進入量産階段，可能在5月靜岡模型展前後上市發售。産品編号為42384的TRF421，Tamiya釋出了官方産品照片和特性介紹。
雙皮帶4WD競賽級電動房車，采用全新設計的一片式碳纖底闆和兩片式二樓闆，相對于2022年上市的TRF420X車型，馬達安裝位置前移了22.7mm，實作等長傳動皮帶，傳動中軸以及皮帶輪位于車架中心，加速過程中減少抖動，傳動輸出更穩定。
新設計的波箱也出現在TRF421車架上，進一步降低重心，全新的超短身大容量避震器USBB (ultra-short big bore)固定在鋁制避震架。
懸挂搖臂進行了強化，懸挂的長度被增加，提升車架的滾動線性表現，同時轉化為更佳的操控響應。
前後防傾杆的安裝位置降低到傳動軸下方，标配1.0mm和1.2mm。
關鍵特性:
The Drivetrain uses a front direct coupling and rear oil-filled gear diff. Equal length front and rear drive belts minimize pitch.
Suspension Arms are a rigid “A” design with 7mm longer span compared to the TRF420X for stable roll, while upper arm mounts can be slid to adjust camber. Three damper pivot positions are provided.
Dampers are 5.5mm shorter than on the TRF420X, for a lighter chassis and lower center of gravity. Attach them directly to aluminum mounts and fine-tune with spacers.
1/10 scale R/C chassis assembly kit.
The drivetrain features the motor position moved 22.7mm toward the chassis center compared to the TRF420X Chassis Kit and has identical length front and rear drive belts for stable drivability.
With updated setup of spur gear and drive belts, only one dedicated nut is required to attach spur gear, which enhances efficiency of maintenance.
The new lower deck is smaller compared to the one used on the TRF420X Chassis Kit to limit ground clearance when the chassis experiences roll.
Choose from two types (one-piece and two-piece) of upper deck. Changing screw positions allows five setup patterns in total.
A-shaped suspension arms are employed for higher rigidity. (The 420X chassis kit uses I-shaped suspension arms.) Longer lower arm spans limit swing width and ensure stability when the chassis experiences roll.
Along with longer lower arm spans, front and rear suspension setups are changed from suspension blocks to suspension balls. Roughly 7mm-longer arm spans limit swing width and ensure stability when the chassis experiences roll.
Toe angle can be adjusted by uprights. (The toe angle of lower arm inside is 0 degrees.)
Three attachment damper positions (inner, middle, and outer) on front and rear lower arms are offered by two types of aluminum bushings.
Changing positions of upper arm mounts by screws allows changes to front and rear caster angles, which is suitable for current high-downforce races. Front caster available angles: 3, 4, and 5 degrees. Rear caster available angles: -.5, -1.5, and -2.5 degrees.
Dampers are shorter by 5.5mm compared to the 420X chassis kit, which provides an exceptionally low center of gravity and reduces the weight, for a more dynamic driving experience.
Dedicated damper ends are used front and rear to ensure the same piston level.
New damper oil seals (Item 51738) are used to keep the maximum oil amount and to make use of oil dampers efficiently.
While the 420X chassis kit uses carbon fiber damper stays, this chassis kit employs aluminum mounts for precise angle adjustments based on the number of spacers used.
Front and rear differential pullies are newly molded while direct coupling and oil-filled gear differential are employed at front and rear, respectively. (The currently sold Hop-Up Option and Spare Parts can be used.)
The front features double cardan joint shafts while rear employs lightweight universal drive shafts. New axle shafts (Item 42388) and 45mm drive shafts (Item 42387) are also used for both front and rear to ensure efficient drivetrain and maintenance.
Newly designed lightweight rear wheel axles enhance durability.
Precision stabilizers are attached at a lower position than drive shafts for efficient maintenance of drivetrain. Includes 1.0mm diameter (x1), 1.1mm diameter (x2) and 1.2mm diameter (x1).
The steering system pairs dual steering arms and Ackerman bush with a new steering bridge.
Three types of new spacers featuring different diameters allow steering angle adjustment.
Includes Sealed Ball Bearings from the TRF series for efficient rotation and Item 22078
Aluminum Differential Holders (0.8mm Offset, 2pcs.).
The newly molded quick-plate design battery holder does not require tape for attachment.
Depending on the battery pack equipped, change positions of spacers and posts. Shorty pack compatible.
Comes with a carrying case dedicated to the TRF421 chassis kit.