Monthly Archives: September 2017

TRF419XR & TB Evo 7 @ Tokyo 2017

Some pictures of the TRF419XR & TB Evo 7 @ the 2017 All Japan Model & Hobby Show.

First look at the XR logo here as well.


Most of the new TRF419XR parts, but this is not the full contents of the TRF419XR Conversion Kit. Everything included is listed here.


TB Evo 7 parts. Lots of aluminium here!



Futaba @ All Japan Hobby Show 2017

A very nice option for the new Futaba 7PX, the Inductive Charging System.




TRF419XR – Higher Quality CAD

Finally a higher resolution CAD picture of the upcoming TRF419XR.

You’ll find more info on the XR in previous posts.


TRF419XR Conversion Product Info

Full product info on the TRF419XR Conversion Set.

42317 TRF419XR Conversion Set

This handy set lets you convert the TRF419X racing chassis into the high-speed, supremely drivable TRF419XR! It features a number of refined parts designs and a new pitch stiffener, to boost cornering speed and steering response, also giving pinpoint control over its flex via various setup options

Featured Components

  • 2.25mm thick carbon fiber lower deck
  • 2mm thick carbon fiber upper deck
  • Center pitch stiffener
  • Front & rear aluminum lower bulkheads
  • Aluminum motor mount
  • Aluminum servo mount
  • Front & rear stabilizers

Set Contents/Information

• This is a 1/10 scale R/C chassis conversion kit. It contains all parts from the TRF419XR chassis kit which are needed to upgrade the TRF419X.
• The new 2.25mm thick carbon fiber lower deck has a symmetrical design, and together with the 2mm upper deck has been designed to optimize the chassis roll point.
• New front and rear stabilizers are secured with ball bearings.
• Center pitch stiffeners adjusts pitch rigidity. A choice of carbon fiber part or turnbuckle is contained.
• 45g LF battery ballast weight doubles as a battery holder.
• Motor mount features more attachment points to allow tweaking of lower deck rigidity.
• New 5mm center shaft for easier assembly.
• Compatible with TRF419X (Item 42301) and TRF419X WS (Item 42311) chassis cars.

TRF419XR Conversion Kit Part Number

Official part number for the upcoming TRF419XR Conversion Kit is now available.

42317 TRF419XR Conversion Set

As already posted last week, the product number for the full TRF419XR chassis is:

42316 TRF419XR Chassis Kit


Mugen MTC1 Build

The countdown to the release of Mugen’s first ISTC electric touring car chassis has been quite long, with first official info released back in April. The final release of the car was slightly delayed, but finally during the last days of August the first batch of cars was ready be shipped.

Since the announcement that Mugen would join the ISTC class I have been following progress on the car regularly, and thought it would be fitting that I actually take a closer look, once it was available. There are a few reasons why I was perhaps more interested in this car than your average TC release. First, as I mentioned, it is Mugen’s first electric TC, and Mugen is a brand with a long history of competitive high quality cars in other classes. Secondly, it looked to be properly designed from the start, and with some unique thought through solutions to common problems, instead of your common copy-paste TC.

Let’s take a closer look!

The packaging is your standard RC kit box, no innovations here. A fairly regular sized box (380x200x100mm), containing the MTC1 kit.


The contents are also packaged in a conventional way, with 7 bags and all parts for one step in one bag (with some exceptions like belts, springs etc.).


With the kit you obviously get the building manual, a parts list with spare and option parts, a list with bag contents for each of the 7 bags, two setup sheets – one for asphalt, one for carpet, as well as two correction sheets rectifying two mistakes in the manual.

The manual could as always be better, but as long as you take your time and are thorough following each step, all the info you need is actually in there. To make it simpler to follow, there could be more text, as well as more separate steps.


Stickers are always important for RCers! Here is what you get with the MTC1.


The carbon fibre chassis is again fairly conventional, both in form and measurements. The thickness is 2.15mm, while it’s 84mm wide. Stiffness is close to your common competitive TC chassis in 2017 I would say.

Sorry for the below par picture of the chassis…


The actual assembly of the MTC1 kit starts with the rear diff. Just as good, as it is one standout feature of the car. Featuring aluminium diff halves instead of the common plastic parts, there are also more features that sets it apart.


Aluminium obviously allow for great precision, and these parts don’t dissapoint, based on first impression. Aluminium also allows greater heat dissipation, and with the small volume of oil in our gear diffs, they have proven to be fairly sensitive to temperature changes. The outer half features a heat sink design to improve heat dissipation even more.


Some people have questioned using alu diffs in electric TC’s, expecting them to be unnecessary heavy. The MTC1 diff proves an aluminium diff designed right can be lightweight.


Here compared to the plastic Tamiya TRF419 diff case.


Here all of the parts of the MTC1 diff (except some pins and screws).

The outdrives are aluminium and super light. As you can see they ride on two bearings (5x8mm) per side, inside the alu diff case, making for a super precise and solid construction.

Large shims (5x15mm) go behind the bevel gears, with smaller shims behind the planetary gears. The gears come like this, so no need to trim them off plastic trees.

A large o-rings seals the cases, while the pulley is attached with the same four screws (2x10mm) that you use to close the diff. Clever.


Laser markings on the case allow you to clearly mark what oil is inside the diff. Again a simple but clever feature. A small bottle of 3000 weight silicone diff oil is included for the base setup, hence the 3K mark chosen here.


Fully assembled diff with a good smooth feel straight out of the box. Very, very close to perfect.


Here you can see the weight of the fully built MTC1 diff, with the recommended amount of diff oil (1.3g).


For the front drive, a solid axle or spool is conventionally included.

The solid axle in itself is an absolutely beautiful one-piece aluminium work of art!


Despite looking like quite a substantial piece, it is again really light.


The complete solid axle fully assembled.

The pulley is the same 34T part as is used on the rear diff, screwed in place by four small 2x8mm screws. The outdrives are plastic or composite, and screwed in place with one 3x10mm screw each side. See pictures above to understand how they key into the alu solid axle. Aluminium (with blades) and steel outdrives are available as options.

Both the rear diff and front spool uses normal 10×15 bearings and eccentrics to adjust belt tension.

Due to the offset of the front and rear belts being different, as far as I can see the rear diff won’t fit straight at the front. Perhaps if you turned the pulley around? Would need a flange on the other side of the pulley then as well. No mention of it anywhere, but anyway a spool seem to be used 95% of the time now.


Weight of fully assembled solid axle setup (with bearings and eccentrics).


The spur gear, pulley holder, and 20T centre pulley rides on an aluminium shaft and 3 small 5x8mm bearings, for a play free setup. The pulley is of the same low friction material as the diff pulleys, and slides over the aluminium pulley adapter, secured by two 2x10mm screws.

An aluminium one-piece pulley/spur gear holder is available as an option part.

No spur gear is included with the kit. I used an Axon 64P gear for this build. The spur gear is secured by four 3x4mm screws, and many modern spurs should fit, although there is a limit in available width due to the motor mount. The internal ratio of the car is 1.7 (34/20 pulleys), and gear tables are available on Mugen’s website.


A picture below to show how both the motor mount and bulkheads, all four are the same, are all keyed to the chassis by two pins.

Also notice how the motor mount is machined, carefully limiting what parts are in contact with the chassis. An extra clever detail is the recess at the rear end of the motor mount for the optional mounting screw. Read on and I will explain further later.


Weight of the intricate motor mount, made out of one piece of aluminium.


The bulkheads (all four the same) are light at 5.2g each.


Here you can see the optional furthest rearward mounting hole for the motor mount, and the 1mm spacer needed if this screw is used. Because of the recess shown three pictures up, the spacer will always go in the right position when you slide it under the motor mount. A very minor detail, but clever design to ease working on the car.


Rear bulkheads and motor mount fitted to the chassis.

The bulkhead spacing on the MTC1 is 20mm, so the left and right bulkheads sits fairly close to each other.

In this picture you can see the three small 3x6mm bearings, under where the spur axle will go. These are placed straight under the 20T centre pulley, and front and rear belts, to help eliminate belt skipping.


Front bulkheads and steering posts. The steering posts luckily have flat spots at the bottom to make securing them easier. I placed an 8mm alu part between them when securing the screws, which held the posts straight and meant I had no problem tightening the screws, without having to use pliers and risk scratching the beautiful parts.


Drivetrain fitted, with upper bulkheads securing the diff. Perfect fit here with no clamping on the diff holders, making sure the drivetrain spins freely.

The rear bulkheads have markings, making it easy to see when setting belt tension with the eccentrics. I set mine 1 step looser than the indicated position, both front and rear.

The front belt is 507mm (169T), while the rear belt is 180mm (60T).


Carbon fibre brace holding the spur shaft from the right side, fastened to the bottom of the motor mount by two 3x4mm screws, and by a 3x10mm screw and two 2mm spacers to the spur axle.


The front upper bulkheads are different than at the rear, because of the need to accept the front upper arm holders.


Overview of the MTC1, drivetrain assembled.


Time for another small nice design detail on the MTC1. The damper towers are chamfered at the bottom, to go with the lower rounded edge of the mounting surface of the upper bulkheads. This allows the tower to sit securely against the bulkhead, despite only two mounting screws.


Front tower fitted with two 3x6mm screws. A standard four mounting holes for the dampers.


Again, four damper mounting holes at the rear. Perfect fit when attaching the towers, both front and rear.


On to the suspension next, starting with the suspension arms of the MTC1.

These are fairly standard TC arms in most ways, the noticeable difference being the damper mount inserts. The damper mounting hole in these is slightly offset, meaning you can adjust the damper mounting position (by 1mm) by inserting these with the hole towards the inside, or the outside of the arm. Outside is the standard setting front and rear, and these give an inner hinge pin to damper mount length of 39.5mm (R) and 32.5mm (F), which you will find is very close to many other manufacturers.

The inserts are attached by 2x6mm screws.


Rear arm weight, with the insert screwed in, is 9.8g.

The arms are very stiff and give the impression of having good strength. Track testing will confirm that.

Droop screws are basic 3x8mm set screws, which you obviously use a 1.5mm hex driver to adjust. Here I would personally have prefered M4 set screws for a larger contact point on the chassis and because they allow you to use a 2mm driver.


Front arm weight is 9.5g, again with the insert obviously.


Front arms now on the car, these held in place with one-piece aluminium suspension blocks, both in front (FF), and behind (FR) the front arms. Inside the suspension mounts , exchangeable arm bushings hold the hinge pins. Different bushing are included, allowing you to set toe /arm sweep as well as roll centres, this the current trend on most electric TC’s today.


Here you can see the one-piece FR mount behind the front arms.


At the rear, there is a one-piece RR mount, while in front of the arms there are separate arm mounts. These can obviously also be used as an option parts at the front of the car.


On the hinge pins, both front and rear, the wheelbase is adjustable with the standard setting being 1mm spacers in front of the arm, and another 1mm spacer behind the arms. The included wheelbase spacers are plastic, while I chose to use alu spacers here.

The quality and fit of these parts are really impressive, right from how the pins in the suspension mounts key into the chassis, on to how the bushings  fit the mounts, and finally how it all fits together totally play-free but still 100% free moving.


Close-up on how the one-piece suspension mounts at the front uses two pins to locate the mount on to the chassis.


The separate suspension mounts used in front of the rear arms use only one screw to be secured to the chassis, this made possible by the two pins keying into the chassis on each mount. Track testing will again prove if this is a good and reliable solution, but fit and precisison is very good.


Roll-bars next, with a 1.3mm front, and a 1.2mm rear bar included.

The roll bars ride on four bearings per end in total, with two flanged 3x6mm bearings per side. Overall the setup is again very play-free, but free moving.


Roll-bar setup at the rear.


Don’t forget the small 2x4mm screws holding the outer bearings in place when you assemble the car.


The steering on the MTC1 differs a bit from your normal TC. Although the basic idea of a two bellcrank steering is similar, it is executed in a different way most other cars, which tend to very much follow each other.

The steering levers are aluminium and ride on bearings on the the steering posts mounted on the chassis. They steering posts can also be attached to the servo mount plate, to give the car a “floating” steering, but more about that later.

The steering plate is a two-piece plastic part, with different inserts included (8,9,10), allowing ackerman adjustment. There are no bearings where the plate attach to the levers, instead the plate/lever connection is done with flanged tubes. These are wider/longer than any normal bearing would be, and give more stability to the steering system, while at least when new just as free as any steering system I have come across until now. It will be interesting to see how this works in the long run, but at least it seems this design has removed much of the unwanted movement found on many cars here.


Underside of the steering levers and plate, clearly showing the replaceable and adjustable insert used for fast and easy ackerman adjustment. In addition to the three inserts, for each one there are also three steps (forward, middle, rearward).

The middle (black) screw, holds the ball on the top side that the servo link attach to. Although not seen clearly in this picture, underneath the head of this screw (on this, the bottom side), there is a steering stopper. The one included is 5mm, while 5.5mm and 6mm options are available. These limit the maximum possible steering angle.


Steering system on the car, and you can see how close the steering posts are to each other, creating a very narrow steering system.


The MTC1 kit build continues with the front suspension, one of the major stand-out features of the car.

Unlike any other current competition electric TC car, the MTC1 comes with sliding upper suspension arms, instead of the single (or double) turnbuckles used on most cars. The upper arms ride on hinge pins, with caster adjusted with caster clips infront or behind the arm.

One of the correction sheets in the kit mentions that you should use two (included) 0.2mm shims, in place of one of the thinner 0.5mm caster clips. Following this guide, the upper arms falls under their own weight, while there is no play. Obviously, the need for the shims is a mistake with the tolerances of the parts, so hopefully this will be corrected in later batches of the MTC1 kit.

The hinge pin is held by plastic bushings inside the lightweight alu upper arm mounts. Two types of bushings are included, allowing three different arm length options.

Camber is set by the captured steel M4 turnbuckle.


Next up the front driveshafts, and the included ones are proper double-joint driveshafts. I have to say these are the best ones I have seen so far when it comes to how easy they are to assemble and get a perfect working driveshaft straight away. Great precision in the parts.


For comparison, here is the difference in weight compared to the TRF (46mm) double-joint driveshafts off the TRF419X. The difference comes from the case, which is aluminum on the Mugen, and 0.9g lighter than the same TRF part.


Here is the other major difference in the front suspension. With the sliding upper arms for caster adjustment, a normal C-hub would not work as there has to be a way for the steering block to pivot front/back.

Mugen have created a unique solution here, with an aluminiun caster block with a caster block bushing allowing the assembly to pivot on the outer suspension pin. The steering block is supported by an aluminium bushing and two 5x8mm bearings.

This solution allows Mugen to keep a similar geometry to ‘normal’  successful TC’s (with regards to pivot points), while doing away with the traditional C-blocks, allowing easy caster adjustment, and creating a very solid and stable front suspension.


The front uprights assembled. As the caster block bushing is locked on to the suspension pin, the elognated hole in the caster block is needed to allow different caster angles.


Again a comparison with a standard suspension off the TRF419X. It is worth noting that the 419X M3 turnbuckle is aluminum (standard) while the large diameter M4 turnbuckle standard on the MTC1 is steel, with an aluminium option available to save some weight.


Complete front suspension now on the car. Once all assembled the MTC1 front suspension feels quite impressive. More solid and less play compared to your standard TC.


Side view showing the unique upright assembly.


The upper suspension arm holders are held in place by two 3x6mm countersunk screws.


The steering blocks use eccentric inserts for the steering link ball. Again, two different inserts are included giving three different options.


Rear camber link mounts are aluminium and screwed on to the rear upper bulkheads from the side, for infinite adjustment.


Rear driveshafts use steel axles and aluminium shafts, with standard 3.5mm plastic blades. Like all critical steel parts on the car, the rear axles are polished for a perfect fit in the 5x10mm wheel bearings.


Rear uprights are very much standard electric TC design.

Wheel hexes are 5mm thick, with a 4.5mm option available from Mugen as well.

Camber link turnbuckles are aluminium, just like the steering link turnbuckles.


The kit standard upper deck again uses a different design, with a two piece setup made from 2.0mm carbon fibre, where the front part pivots on large 6mm aluminium pivot balls. The front upper deck is also mounted very low in the car, mounted to an aluminium bracket between the bulkheads in the front of the car.

A more normal looking one-piece upper deck, mounting straight to the front and rear bulkheads, is available as an option part, but the included pivoting design is said to make the car very easy to drive and working better on most (low/medium grip) tracks.


Pictures of the two-piece upper deck on the car.



With the upper deck design, together with the alu pitch stiffener (more later) and how the motor mount is fastened in the standard setup, the flex point of the car appears to be quite far forward.


With the basic chassis all assembled, it’s time to move on to the dampers.

Below all the parts of the MTC1 dampers. I’ll give a brief description, from left to right.

  • The bottom spring collar is a super low and light design, made possible by the fact that they fit tightly over the lower ball joints.
  • The piston and shaft assembly is in reverse to normal, with the top e-clip going onto the shaft first, followed by the piston, and finally the lower clip. The included pistons are 4-hole pistons, and come as separate machined pieces.
  • The damper cylinder has an inner diameter of 11.2mm and an inner depth of 18mm. This means that the diameter is industry standard today, but with around 3mm more depth, giving the MTC1 dampers a larger oil volume.
  • Top view of the assembled shaft/piston. The upper clip goes into a recess in the top of the piston, helping stabilise the piston. This is also the reason why they have to be assembled in the order mentioned above. Fit is tight and precise, making the piston play free for consistent damping.
  • The alu hats have etched markings for different oils, and with the clip-ons you choose the right mark according to what oil you are running. Different clip-ons are included, as there is a small marking on these for the piston you are running as well. 450 weight oil is included with the kit. The alu hats also have a hole in them, for oil overflow.
  • Upper spring collars and bladders are fairly standard, although I wish the collars had marks for easier ride-height adjustment.
  • The top plastic hats have a small breathing hole.
  • The lower damper ball joints come in two versions, with the ones used at the rear 1mm longer than at the front.


Dampers built, sorry for the blue holder!

The dampers are really easy to build, and all came out the same first time and feel really solid.


The included springs, the same front and rear, are made from 1.4mm thick wire and are 5.5 turns. They are marked as 1.56.

Total damper length at the front, built with the indicated 11mm visible shaft length, is 56.5mm.


Rear damper length, again built with the indicated 11mm visible shaft length, is 57.5mm. Spacers are used behind the lower ball joint, with a 1mm spacer up front and 2mm spacers at the rear.


The aluminium/carbon fibre floating servo mount.

The carbon plate mount to the alu part with three countersunk screws and two pins, all not on the same line as well, making the mount super solid.


The mount is attached to the chassis by three screws and two pins as well, for a bomb proof mounting.

The outer servo post is plastic, with one pin and one screw.

The servo mount standard position is that it is mounted on the centre line of the chassis. Because of where the front belt is, located close to the centre line, you are required to cut the lower mounting ear of your servo if you want to use this position for the servo mount. An offset option is available with the servo mount, as you can see from the extra holes in the bottom of the aluminium part.

This is also the reason why there are two sets of holes in the front of the carbon plate for the steering posts. These are used if you want a floating steering setup, with the steering system attached to this plate instead of the chassis..


In the car, in the standard centre line mounting option, this is how the servo mount looks.


Included with the car you get this centre aluminium pitch stiffener. This can be attached with up to three screws to the chassis, and also secured to the motor mount by a fourth screw.

In the below picture you can also see the upper deck pivot mount and how the front belt tunnels under the servo mount.


Overview from the bottom of the chassis where you can see how the servo mount is mounted, the optional offset mounting holes, as well as how the pitch stiffener is mounted with three scews to the chassis and one screw to the motor mount.


A neat feature included with the MTC1 is this small plastic box where you can hide your servo, ESC receiver, and transponder wires. You can open and close the small box with a single 2x6mm screw, and there is is one higer edge on it where you can fasten your transponder and/or ESC switch if you want. The box is meant to go underneath your receiver. Obviously optional if you choose to use it.


The battery fits on the chassis at an angle, due to the spur gear position and motor mount design. Adjustable inner stoppers front and rear uses simple screws and spacers, while fine-adjustment front/rear stoppers are countersunk screws that go into the plastic battery holders.

The battery- and tape holder will do a good job of holding the battery, but it is a shame that a neater solution was not engineered for this, as the car otherwise is beautifully designed and made.


Muchmore battery in place to illustrate the battery positioning.


Yet another unique solution for the MTC1 is the front bumper, with some aero consideration taken into the design, I believe for the first time on an electric TC. Two scoops will act as a front wing or splitter, and it would be interesting to test this back to back with a more normal design to see the effect of it.


Body position (front-rear) is a useable way of tuning in TC racing, and instead of having multiple bodies mounted differently, on the MTC1 you can adjust the body with the body mounts.

The front posts can be turned 180 degrees to move the body more forward. At the rear you can match this by removing the included specific body post spacers seen in the picture.


Front body post in rearward position, visible by the mark on the body post collar pointing towards the rear.


Spacers in use between the tower an drear body post, for the rearward body position.


The included foam bumper is two-piece, with the intention being that you can glue (or double-side tape) the extension if you run a forward mounted body to minimise any air-gap between the bumper and body.


Foam bumper mounted with the included carbon bumper brace holding down the foam.


Another nice inclusion in the kit are these super lightweight and finely adjustable body height adjusters. Made from aluminium and anodised, these allow super fine and repeatable fine tuning of the front and rear body height.

These are also the final parts of the kit build, meaning we now have a completed Mugen MTC1 chassis kit built and ready.


Finally a few shots of the finished MTC1!








Mugen’s MTC1 is a super impressive kit, especially as a first electric TC release from the company, and would be equally impressive from any company really. Finally a solid company that has taken the time and effort to create something new, instead of merely following and copying each of the latest trends in the market. Sure, the MTC1 is a coneventional 2017 TC in many ways, but where there are opportunities to innovate without taking too big risks with the overall performance, Mugen have thought about different solutions, then through proper RnD designed and produced them in a very impressive way. Good job Mugen!

I really look forward to testing this car, but as is always the case for me, local climate and track availablility compromises will mean that track testing is still some way into the future. Don’t worry though, once tested, I will do follow up posts.

FYI, this build has not been supported in any way from any company.

Thanks for following the MTC1 kit build!



MTC1 – Up Next

Up next…

Follow along during the next few days.


TRF419XR First CAD Picture

A first low resolution CAD of the upcoming Tamiya TRF419XR Chassis Kit.

Also a part number:

423116 TRF419XR Chassis Kit

1/10 R/C TRF419XR Chassis Kit

The thoroughbred 2 belt-driven 4WD TRF419 chassis series makes another evolutionary leap with the TRF419XR, designed for enhanced cornering speed and steering response. Refined carbon fiber lower (2.25mm thick) and upper (2mm thick) decks optimize the roll point, while a new center pitch stiffener allows adjustment of pitch rigidity. Front and rear stabilizer bars are secured with ball bearings for precise, repeatable setup changes. Comes with carbon fiber damper stays for TRF dampers and the included TRF super short big bore dampers, plus an LF battery ballast weight.


MTC1 More Detail Photos

More pictures of the details of the production Mugen MTC1, which is now available.
















TRF419X First Details


Tamiya USA have released first official information on the forthcoming TRF419XR that will be available as a full kit for the Japanese market and as a conversion kit for all other countries. The XR variant features a number of refined parts designs and a new pitch stiffener, to boost cornering speed and steering response, as well as giving pinpoint control over its flex characteristics via various setup options. Key updates to the TRF419X is a new, symmetrical 2.25mm carbon fibre lower and 2.0mm upper deck, a centre pitch stiffener, a redesigned aluminium motor mount, new front and rear lower bulkheads as well as an updated servo mount and new front and rear stabilisers.

Key updates:
– New front and rear stabilisers are secured with ball bearings for precise, repeatable setup changes
– Super short big bore dampers and damper stays are included. Also in the box are dedicated damper stays for separately sold TRF dampers
– A new centre pitch stiffener allows adjustment of pitch rigidity. A choice of carbon fibre part or turnbuckle is contained
– The 45g LF battery ballast weight doubles as a battery holder
– More motor mount attachment points allow you to tweak lower deck rigidity to match the surface
– Centre shaft diameter has been changed from 4mm to 5mm, for easier assembly
As for the conversion kit, the set will fit both the TRF419X and TRF419X WS and it will bring both to full XR specification.

Included parts:
– 1/10 scale R/C chassis conversion kit. It contains all parts from the TRF419XR chassis kit which are needed to upgrade the TRF419X
– The new 2.25mm thick carbon fibre upper deck has a symmetrical design, and together with the 2mm upper deck has been designed to optimise the chassis roll point
– New front and rear stabilisers are secured with ball bearings
– Centre pitch stiffeners adjusts pitch rigidity. A choice of a carbon fibre part or turnbuckle is included
– 45g LF battery ballast weight doubles as a battery holder
– Motor mount features more attachment points to allow tweaking of lower deck rigidity
– New 5mm centre shaft for easier assembly
– Compatible with TRF419X (Item 42301) and TRF419X WS (Item 42311) chassis cars