Tamiya TRF 501X World Edition Project

TRF stands for "Tamiya Racing Factory", and any chassis, kit, or part that says TRF on it is automatically cool.  How can I be sure?  Just try building one and you'll agree with me.  The history of the TRF line can be a bit difficult to trace since it filtered into touring cars and buggies at different times.  No matter how you trace it, TRF started in the '90's and continues to this day.  If we focus solely on 4WD buggies though, things become much more compressed.  The 4WD TRF racing buggies were numbered with a 500 series code, and the whole evolution lasted less than a decade before they were consigned to history.  I'm not a racer and can't explain exactly why that happened, but discontinued products always come down to lack of sales and/or profit.  New TRF 500 series chassis could easily run over $1000 before any electronics or tires were installed, and I'm guessing that cost coupled with the associated performance just wasn't competitive in the market.  If you are a Tamiya collector though, you need to know about these glorious buggies.  I spent a considerable amount of time researching the five different chassis types that were available in those eight short years

	TRF501X (49401):  This model was first available in December of 2006.  Features include laterally mid-mounted motor, dual belt 4WD, carbon chassis with dual upper decks, ball differentials, overdriven front axle (36T pulley rear, 35T pulley front), two pad slipper clutch, aluminum aeration dampers, aluminum front, rear, and center bulkheads, full ball bearings, carbon shock towers, dual bellcrank steering, front and rear CVD style universal axles, double wishbone suspension, turnbuckle upper links, high torque servo saver, and 48p gears.  Note that this model was made specifically to work with 6 sub-C sized battery cells in a saddle configuration.  The kit came with an extremely low profile unique body (1824090) and a full under tray.  The kit also included white dish wheels but no tires.
	TRF 501X World Edition (42105):  This upgraded version of the 501X was first available in November of 2007.  Changes include cam instead of straight bearing posts on center bulkhead, 18T center pulleys instead of 16T, 91T spur instead of 96T, improved slipper pads, 37T diff pulleys instead of 36T rear and 35T front (no overdrive), 369mm drive belt instead of 363mm to accommodate different pulleys, 12 balls in ball diffs instead of 8, strengthened upper arm mount,modified rear shock tower, different default front shock mounting holes, 10.5mm pins in universal shafts instead of 9.8mm, aluminum rear uprights with longer ball joints, aluminum caster blocks with longer ball joints, front and rear sway bars, new Delrin pistons and rod guides replace W parts tree, longer piston rods, and softer rear springs.  Overall gear ratio changed from 12.7:1 to 11.0:1.  Although the body at first glance appears to be identical to that used on the standard model, the World Edition has a unique body (1824097) with subtle aerodynamic changes.
	TRF 511 (42139):  This model was first available in March of 2009.  It is extremely similar to the 501X at first glance incorporating most of the updates of the WE.  Additional changes include new chassis plate with slightly shifted components (same profile), center bulkhead altered for easier slipper removal, split (2-piece) upper arm mounts, split rear suspension mounts, modified upper bulkheads, less overlap on upper decks for easier removal, center bulkhead stiffener removed, modified lower arm geometry, rear upper links moved to forward side of uprights, different default front shock mounting holes, reinforced 369mm drive belts from the DB-01, under tray attaches with more screws and no tape, and 511 does not use upgraded WE Delrin shock parts. This kit did not come with a body, under tray, or wing, but was intended to work with the a more conventional new body (54133).  A separate version of the kit was later available with gear differentials (42213).
	TRF 502X (42183):  This model was first available in November of 2010.  The chassis is substantially altered.  Changes include switch to shaft drive and longitudinal motor, completely different center bulkhead, similar ball diff but with a bevel gear instead of a pulley, front and rear bulkheads are now plastic, new steering cranks, and all electronics are repositioned.  The  suspension is the same as the 511 and the model is intended to use the same body.  Although no motor came with any of the TRF chassis, this is the first version to show a brushless motor in the manual as a baseline.  No pinion gear was included in the kit.
	TRF 503 (42275):  This model was first available in March of 2014.  This is an evolution of the older 511, not the shaft driven 502X. Changes include aluminum chassis instead of carbon, longer wheelbase, unequal length drive belts, gear instead of ball differentials, new shock towers, different style universals using retaining rings instead of set screws, new uprights with more adjustment options, big bore dampers, and a new cantilever servo mount. It was intended to work with the same body as the 511 but without the under tray.  This was the first version to do away with the chassis plate slots for sub-C batteries and was intended for rectangular saddle packs instead.

These chassis cost a fortune when they were new and readily available, so you can imagine what they are like to acquire now.  I knew I would never be lucky enough to own all of them, but I figured I had a shot at getting at least one.  After losing all my buggies in the 2022 fire, I figured having a single TRF 4WD buggy would allow me to represent the high end of the Tamiya line in my collection.  I decided I would be OK with any of them, but my preference was for the World Edition if I could find it.  By coincidence, that was exactly the model that popped up in my search first.  All things considered, it was "reasonably" priced.  It wasn't new in the box, but it didn't look like it had ever been run either.  It also came with a pretty good pile of additional upgrades so I couldn't pas it up.  I started by completely disassembling it and then building from scratch, making note of anything that was different from the stock model.  I was forced to learn a lot in the process which made it all the more enjoyable.

I installed a modest brushless power system.  I intend this model to be a runner, but I am not going to brutally bash it into submission like I might with some other buggies.  It is just as lovely to drive as I imagined.  Is it worth the massive premium over a traditional Tamiya buggy?  It is if you are me.  A cheap modern TT-02B or DF-03 is actually perfectly good by comparison, but it is not as fun to build nor does it give you the same rush of adrenaline as you advance the throttle.  I'm sure there are differences on the track, but I have no intention of racing any time soon.

This was the first model I built after the 2022 fire destroyed my entire collection, so for a time it was the only model in my collection.  For that reason and others, it is precious to me.

Page 1: Assembly

Page 2: Final Photos