1/10 R/C TRF421 Chassis Kit

The TRF series welcomes the brand new TRF421 chassis kit.

This R/C model assembly kit creates a 2 beltdriven 4WD, carbon fiber double-deck chassis. New features - such as updated drivetrain, lower deck featuring new shape, updated (one-piece or two-piece) upper deck, front and rear A-shaped upper suspension arms,  adjustable front and rear caster angles, and shorter dampers - will surely provide superior performance.

About the Model 
• This is a 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 (Item 42382) 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. (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. 

Tamiya TRF421 Tech Spec Images

• Changing positions of upper arm mounts by screws allows changes to front and rear caster angles (ref. table below), which is suitable for current high-downforce races.

Front Rear 
3°      -0.5°
4°      -1.5°
5°      -2.5°

• 
  Dampers are shorter by 5.5mm compared to the 420X chassis kit, which provides a very low center of gravity and reduces the weight, for a more dynamic drive. 
  • Dedicated damper ends are used front and rear to ensure the same piston level. (ref. Image 12)
  • 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 via the number of spacers used. 
  • Front and rear differential pullies are newly molded (planned) while direct coupling and oil-filled gear differential are employed at front and rear respectively. (The currently-sold Hop-Up Option and Spare Partscan be used.)
  • 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.).
  • 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. 
  • Comes with a carrying case dedicated for the TRF421 chassis kit. 
  • Please note that this chassis requires separately sold body, battery pack, motor, tires, wheels, and R/C equipment.

Satoshi Maezumi, also known as "Paisen RC", is one of Tamiya Japan’s most experienced and passionate RC drivers. In this video, he shares expert setup tips, driving techniques, and product insights.

Please note: the video is in Japanese only, but the visuals and demonstrations are easy to follow for all RC enthusiasts.