Description This R/C model assembly kit takes the TRF421 (Tamiya Racing Factory) to the next level by creating the TRF421X. TRF421X incorporates racers feedback from the past year to refine the 2 belt-driven 4WD platform with updated suspension and low center of gravity setup options for superior performance on high-traction track conditions. New Features: • Aluminum Motor Mount: Motor attachment position is 1.04mm lower than that of the TRF421 chassis kit for a lower center of gravity and more stable cornering, and a contemporary design ensures exact assembly. • 2.0mm thick aluminum lower chassis deck: The new lower deck is made of aluminum. It allows lower motor attachment position for optimal balance, chassis flexibility and weight distribution. NOTE: Compatible with standard TRF421 chassis if the new aluminum motor mount is used in conjunction. • Upper Chassis Deck: Both types (one-piece and two-piece) of upper deck shape are updated for improved chassis flexibility. NOTE: Compatible with standard TRF421 chassis. • One-piece upper deck attachment: Tubes, dedicated titanium low button-head screws and shims are used to attach the one-piece upper deck. Adjust flexibility by using 0-0.3mm shims. NOTE: Compatible with standard TRF421 chassis. • Upper and lower suspension arms (new material) & front and rear damper stays: A- Damper attachment positions are moved 1.0mm toward the inside with new front and rear damper stays. B- Both upper and lower suspension arms are molded in carbon reinforced nylon (the TRF421 chassis kit features glass reinforced nylon) to ensure suspension flexibility and to improve stability on hot temperature or high grip or carpet surfaces. NOTE: Compatible with the standard TRF421 chassis kit when changing both damper stays and suspension arms. • Drive shafts & drive train: A- New front double cardan drive/joint shaft and rear lightweight aluminum universal shafts feature bearings (Drive shafts used on the TRF421 chassis kit feature swing shaft caps.) to limit friction. B- The design and materials of front direct spool cups and rear differential are changed. (Materials are changed from aluminum to steel. • Upper arm mounts: New upper arm mounts feature 1mm narrower pivot attachment width for improved cornering response, and upper arm attachment with bushings to adjust pitch. A modern design helps ensure exact assembly and stability under vibration. NOTE: Compatible with standard TRF421 chassis. • Knuckle arm: New knuckle arms feature new hole positions for front and rear, respectively. The hole for front makes Ackerman position outward for more direct steering and the hole for rear makes adjuster rod attachment positions backward for best rear grip on low or middle traction surfaces. NOTE: Compatible with the standard TRF421 chassis kit. When using knuckle arms included in the TRF421 chassis kit, 4 setup options (2 choices for front and rear respectively) are available depending upon road surface and driving style. • Stabilizers (sway bars): Precision stabilizers can be chosen from 1.2 diameter (x2) and 1.3 diameter (x1) depending upon road surface and driving style. NOTE: Compatible with the standard TRF421 chassis kit. • Receiver weight & battery weight: Newly added receiver weight (20g) and 0.6mm thick battery weight (30g) ensure best weight balance. Receiver weight is attached by one screw and works as cooling fan mount. NOTE: Compatible with the standard TRF421 chassis kit.
