Description
Overview
The Tamiya TRF421X Chassis Kit represents the pinnacle of Tamiya Racing Factory engineering—the most advanced racing chassis ever developed by TRF. Unveiled as the sensation of the 2026 Toy Fair competition category, this successor to the acclaimed TRF421 is packed with new and improved features directly derived from TRF racing team experience at international events including the IFMAR ISTC Worlds. Every detail has been scrutinized and improved to deliver world-class touring car performance.
Built on a brand-new 2mm thick aluminum chassis, the TRF421X features a proven 2-belt drive system with numerous refinements. The motor position is now even lower thanks to a new motor mount, front and rear wishbones are made of carbon fiber reinforced plastic for superior stiffness, and the damper positions are flatter to accommodate the latest hypercar bodies. With updated suspension geometry for higher cornering speeds, ball bearing driveshafts, and an expanded range of tuning options, the TRF421X sets a new benchmark for competitive touring car racing.
Key Features
- 1/10 scale competition touring car chassis assembly kit
- Brand-new 2mm thick aluminum chassis with optimized flex characteristics
- Lowered motor position (1.04mm lower than TRF421) for reduced CG
- 2-belt drive 4WD system with proven efficiency
- Carbon fiber reinforced plastic (PA-CF) front and rear wishbones
- Ball bearing type driveshafts for improved efficiency
- Two different upper decks included (one-piece and split)
- New adjustable center mount with sleeves, shims, and titanium screws
- Flatter damper positions for low-profile hypercar bodies
- TRF dampers with hard red springs included
- Updated steering geometry for higher cornering speeds
- Multiple anti-roll bars included (2x 1.2mm, 1x 1.3mm)
- Balance weights for battery and receiver areas
- All aluminum parts in signature TRF blue anodized finish
Performance Benefits
- Lower center of gravity from repositioned motor
- Improved traction from new suspension components
- Higher cornering speeds from optimized steering geometry
- Ball bearing driveshafts reduce friction and increase efficiency
- PA-CF wishbones offer superior rigidity over glass fiber versions
- Extensive flex tuning via multiple top deck and center mount options
- Rear center stiffener/flex brace for fine condition tuning
- Alignment pins on motor mount and bulkheads ensure precision
- Compatible with TRF421 suspension components for expanded tuning
Usage Notes
Designed for competitive on-road touring car racing on high-grip carpet and asphalt surfaces. The TRF421X is optimized for experienced racers competing at club, national, and international levels. The chassis offers exceptional tunability for varying track conditions through extensive setup options. While focused more on performance than the 421, it remains accessible and easy to work on. Recommended for experienced builders and racers. Body, wheels, electronics, and motor sold separately.
Technical Specs
- Scale: 1/10
- Drive: Belt-driven 4WD (2-belt system)
- Chassis: TRF421X
- Chassis Material: 2mm aluminum
- Suspension Arms: Carbon fiber reinforced plastic (PA-CF)
- Dampers: TRF aluminum oil-filled with hard red springs
- Driveshafts: Ball bearing type (1.5x4mm bearings)
- Upper Deck: Two versions included (one-piece and split)
- Anti-Roll Bars: 2x 1.2mm, 1x 1.3mm
- Bearings: Full ball bearings throughout
- Vehicle Type: Competition touring car
- Manufacturer: Tamiya Racing Factory
- Item Number: 42391
What's Included
- Complete unassembled TRF421X chassis kit
- 2mm aluminum chassis plate
- One-piece upper deck
- Split upper deck
- PA-CF front and rear suspension arms
- Ball bearing type driveshafts
- TRF aluminum oil-filled dampers with hard red springs
- Front and rear stabilizers
- Anti-roll bars (2x 1.2mm, 1x 1.3mm)
- Center mount hardware (sleeves, shims, titanium screws)
- Rear center stiffener/flex brace
- Balance weights (battery and receiver area)
- Comprehensive instruction manual
Needed to Complete
- 1/10 touring car body shell
- Touring car wheels and tires
- 2-channel radio system (transmitter and receiver)
- Low-profile steering servo
- Electronic speed controller (ESC)
- Brushless motor
- LiPo battery pack
- Compatible battery charger
- Basic assembly tools
Summary
The Tamiya TRF421X represents the ultimate expression of Tamiya Racing Factory engineering for competitive touring car racing. With its lowered motor position, carbon fiber reinforced suspension arms, ball bearing driveshafts, and extensive tuning options, this chassis delivers world-class performance for serious racers. The signature blue anodized aluminum parts, dual upper deck options, and proven 2-belt 4WD system make this the definitive choice for competitors seeking the best from TRF.