Tamiya TRF 420X Project

The seventh generation of the TRF touring car line began in December of 2019 with the 42345 TRF 420 chassis exactly two years after the previous generation.  Whereas there had been virtually no obvious difference between the TRF 418 and the 419, the TRF 420 changed almost everything.  Although the general layout remained the same, this was a virtually brand new chassis with new suspension, bulkheads, differentials, sway bar mounts, and almost everything else.  Tamiya must have been pretty happy with this chassis because they left it exactly the same until two and a half years later (May 2022) when they released the updated 42382 TRF 420X.  It included a number of parts which had previously been options including both a carbon and aluminum lower deck.  I present a detailed list of the changes to the new generation of the model in the table below.

TRF 420X

Includes optional aluminum lower chassis deck New bulkheads with revised sway bar attachment and optional rear toe control kit attachment New adjustable rear stiffener New center bulkhead and motor mount with revised center pulley position New floating electronics deck Rear axles now 43mm instead of 44mm Revised more flexible shock towers New slotted upper deck with optional stiffeners Updated battery holders no longer require tape Updated cooling fan mount

There were also various modifications available.  The 42350 Aluminum Lower Deck was 2.0mm thick and replaced the 2.25mm thick carbon chassis of the regular TRF 420.  It was intended to be used with the thinner 1.75mm 42349 Carbon Upper Deck.  Incidentally, the TRF 420X included both a carbon and an aluminum lower deck, but neither were the same as the parts from the TRF 420.  The 47440 Long Damper Stays were available for drivers who wanted to use regular length shocks instead of the super short versions included with the TRF 420.  Finally, the 54887 Toe Control Rear Suspension could be used with either the 420 or the 420X and added turnbuckles to the rear uprights for continuous toe adjustment.

While using mostly new parts, the TRF 420 is still architected like previous models. Like all the TRF touring car chassis, this a twin belt driven 4WD model with carbon fiber chassis plates (aluminum optional), loads of machined aluminum parts, and generally the best parts Tamiya could come up with including hardware and axles.  The general layout with the electronics on one side and the battery on the other is the same.  The real changes are all in the details and are explained much further in my build journal below.