42389 Tamiya TRF104 Review, set-up and race report

As anyone that has followed this site knows.. I'm a big fan of racing, F1 and Tamiya, so it would be no surprise that I always am interested in the TRF F1 kits. The main issue is that as a class in the UK it is just not very popular nowadays. No local clubs race them, which does make owning the latest 1/10 onroad race kit a bit hard to justify. Despite that I bought the Tamiya TRF104 as soon as it was available. It has sat in it's box for some while, ready for a race, and low and behold the M.I.C.C decided to have a one off exhibition race in the final round.. This was the opportunity, so I decided to enter.

If you’ve followed this site for any length of time, you’ll know two things about me: I love F1, and I love Tamiya. So the TRF Formula 1 kits have always had a certain pull.

The reality, though, is that F1 as a class in the UK has faded. Hardly any local clubs run it anymore, and that makes buying a dedicated 1/10 F1 race chassis feel… indulgent. More heart than head.

And yet, when the Tamiya TRF104 was released, I didn’t hesitate. I ordered one immediately.

It arrived. I admired it. And then… it went back in the box and hidden away from my wife..

For months it sat there, pristine, untouched, almost taunting me. A car built to race, waiting for a grid that didn’t really exist.

Then came the message.

M.I.C.C announced a one-off F1 exhibition race as part of their final round. Just like that, the excuse I’d been waiting for appeared.

The TRF104 was finally getting its moment, I entered as soon as booking was available and delved into the storeroom to grab the box.

The TRF104 has a lot of new features that elevate it over the previous generation of Tamiya F1 cars and it puts it on a good footing with rival manufacturers. Let's crack on with the build..

The kit comes with a 2.5mm carbon fibre chassis, however I was going to race the car on high grip carpet so I took a different route.

I Instead decided to build the car with the MTTR 2.0mm aluminium deck. This gives me more weight lower down. The chassis weights in at 71g, 20g heavier than the kit supplied carbon chassis. 

As you would expect with a TRF kit, there is a lot of blue bling, and we start off with the Front and centre bulkheads, the steering post and the servo post. 

The centre bulkhead also acts as the second servo post. Here you can see the exquisite machining of this part.

The front lower carbon arms are mounted on these posts. 

The carbon arms are 2.5mm thick, and they have settings for a narrow or wider front end width. Note: This is not a 200mm wide front end like the older F103, just a tuning setting. 

Trapped suspension balls are next up, I brushed these with some Tamiya 42280 VG fluorine liquid to ensure they are silky smooth.

Suspension balls are held in place with a 6.5mm 0-ring, steering stoppers are attached and the arms are now mounted onto the posts in the narrow track width position. 

Now things get really interesting. All previous Tamiya F1's have had steering linked directly to the servo saver, now we get a steering linkage that can allow easy Ackerman adjustments and you can also change the rod heights. Many rival manufacturers have similar systems, so it is great to see Tamiya stepping up.  The grooves in the steering arm allow you to set the Ackerman in four positions. 

Once you select the position you just lock it down with a screw. Simple and clean. 

The steering linkage slides onto the post and is held in place with the front chassis stiffener. The entire movement is silky smooth, and with the right shims included I had no slop.

The upper caster plate has three different settings 6, 9 or 12 degrees. It locks down nicely with two screws. The caster plate also has the ball connectors that hols the upper arms, you can add shims here to change the front roll centre for more tuning. 
The front upper arms resemble those of the TRF421 / TA08 and they are very easy to build. These provide the TRF104 with easy to adjust camber setting with a 2mm hex wrench.

For the steering uprights I delved into my spares and mounted Tamiya 54357 Adjustable Metal Upright Set. They allow you to have a trailing steering axle, and also provide more height adjustment as they are not as tall as the kit uprights. Even though the chassis is advanced, the classic kingpin / coil spring set-up is used. It's light, durable and easy to adjust. 

The lower brace will hold the motor mount, the ball connectors allow it to rotate independently to the main chassis. 

The motor mount allows you to change the wheelbase from long to short, and to adjust the height of the rear axle. 

The kit comes with 0, 1 and 2mm offset axles. Tamiya also makes an option part that provides 1.5 and 2.5mm offsets. 

The rear suspension plate is FRP, I opted to mount a MTTR carbon rear plate, it should be a little more durable, and saves 3g of weight. 

The blue aluminium suspension mounts are attached, ready to hold the balls from the rear motor mount. You don't want to attach both at this stage as you will not be able to attach the motor mount.

The motor mount is now attached and the motor mount moves very freely with no longitudinal movement. 

The roll springs are held in place with a nice carbon fibre plate. You can adjust spring pressure with the grub screws. 

The rear wing mount is attached. The TRF104 gives you options here. The kit set-up has the wing mount attached to the motor pod like most F1 cars. The other option is to mount the wing onto the rear brace. This detaches the wing from the motor pod, so when you turn a corner the wing stays flat.

The TRF104 also has rear stiffeners, these hold the rear bodyposts and will also grab onto the rear brace assembly.

The stiffeners old the rear brace firmly on the rear of the main chassis. 

The kit comes supplied with a carbon rear axle, but I opted to fit the Tamiya 84381 steel rear shaft. I’d used this to great effect on both my Tamiya TRF101 and Tamiya TRF102, where the added weight helped generate a noticeable boost in rear traction.

However, as I discovered later, it’s probably not necessary here. The Tamiya TRF104 already has plenty of rear grip, so in hindsight it would make more sense to stick with the lighter carbon shaft supplied in the kit.

The TRF104 supports modern racing lipo packs (as well as LIFE round packs).  I opted for the shorty lipo settings. The carbon brace can slide to ensure the lipo fits perfectly.

Roll dampers attach to a carbon plate. I used eXcelerate 150k damper grease as I was going to run the car on carpet. 

The pitch damper is a classic TRF unit, and the fluorine-coated piston rod is a clear sign that this is a full-spec kit. I’ve built countless of these dampers over the years and they’re always a pleasure to assemble.

One small tweak I make is adding a 0.3 mm shim to slightly preload the O-ring, helping to ensure a tighter seal and prevent any oil from weeping out.

The chassis is now complete. It was a quick and straightforward build, and the end result feels like something very special.

With the alloy chassis, steel rear axle, and titanium/aluminium hardware, the final weight comes in at 313g. Switching to the carbon chassis and carbon rear axle would drop around 35g, giving a significantly lighter overall package.

Next up I mounted the wings. I used the Mon-tech formula 22 wings front and rear. 

The Raceway RC sticker set is really good quality. I used a heat gun to ensure the decals perfectly. This looks incredible.  Can you guess what team it is?

I got the electrics mounted in the chassis. It’s been a while since I last raced F1, so my 21.5 motor is definitely showing its age 🙂

The main challenge was routing the servo wire neatly under the battery to the receiver. There’s no dedicated cut-out, so I ended up running it underneath the battery, which worked well enough with a bit of careful positioning.

Now for the bit that makes F1 so special.. the body. Raceways RC came up trumps with this excellent Aston Martin F1 sticker set for the Exotek F1 body. It is a good fit for the TRF104 with no excessive trimming. 

Raceway RC make superb driver helmets, the detail on this Alonso lid is superb. 

Time was running out and I put in a late night on the Saturday ready for Sundays race.. 

I never normally run two classes, as I always find it leaves me with too little time to properly dial in a setup for either car. But I really wanted to run F1, so I went into the day knowing it could be a bit of a challenge... and I was going to be proven right. 

The M.I.C.C round 3 layout looked excellent, and I was keen to finally get the TRF104 out for it's first run in practice. We were running ECTS foam tyres, so I expected grip, I just didn’t expect quite that much.

TThe car tracked straight and felt stable, but the moment I tried to turn it, it took an age to rotate. On top of that I was massively underpowered on the straights. I had no real idea what gearing I should be aiming for, and my ancient Muchmore 21.5 motor simply wasn’t producing anything like the revs the other drivers had. Still, that’s what practice is for, so I got to work making changes.

After a quick chat with a fellow F1 racer, I was given a rough FDR to aim for. From there my focus shifted entirely to finding more rotation, because the rear of the car was so stable that it just wasn’t quick enough through the corners.

The first qualifying round was a complete write-off. I started having steering issues and quickly realised the servo was working loose. This was entirely my own doing after moving the electrics around late into the night and not checking the screws properly. Things were not exactly going to plan.

For the second qualifier I made a few changes: more front toe-out and a fresh application of thick grease in the rear side dampers. I’d been too conservative with it first time out and the pod had far too much movement. This time I used AW grease, which seemed to cling to the rods much better.

The improvement was immediate. The car was much better and I managed to go sixth fastest in the round. Even so, it was still too slow to rotate in the corners, and combined with the lack of motor speed I was losing valuable time in the more technical sections, which really hurt the lap times.

The third qualifier was another washout. I got swiped hard and the car was no longer tracking straight. I limped around for a few laps before it stopped steering altogether. Back in the pits I couldn’t immediately spot anything obvious, but after a closer inspection it turned out the servo plug had worked loose.

That left it all on the final qualifier. I needed a clean run.

The car was definitely better, but I still couldn’t get enough rotation into it. Running two classes meant there simply wasn’t enough time between heats to properly chase the setup, so I was limited to quick tweaks only. A touch more front camber helped and I found a little more pace, but I then lost several laps stuck behind a backmarker. I still improved, but there was definitely more speed in it.

After an eventful qualifying, I ended up P8 on the grid—not bad for the first proper outing, but still frustrating. I knew the car was nowhere near its optimal setup, and I certainly wasn’t getting close to the speed I know both the chassis and my thumbs are capable of.

Lining up for the final, all I really wanted was a clean race and the chance to make up a few places.

The race itself was full of battles all through the field. I did my best to stay clear of the chaos and just focused on circulating the Tamiya TRF104 cleanly. I was enjoying it, picked off a nice overtake early on, and the car remained incredibly easy to drive. The problem was it still felt locked down and sluggish out of the corners.

I was already regretting not getting the car ready earlier and doing some proper setup work at a local club. At the same time I was wondering whether it might finally be worth investing in a new 21.5 motor. The fact I had enough spare mental capacity to think about all of this mid-race just proved how little I was actually able to push the car.

In the end I crossed the line in sixth place, which is perfectly respectable for the first run of a new car in a class I haven’t raced in years.

And that really highlights the biggest issue with racing F1 in the UK, there just isn’t enough club support for it. It’s such a fantastic class, and one I’d genuinely love to race more often, but outside of the nationals I just can’t see many opportunities to run this chassis regularly.

This is such a shame as the TRF104 is the best F1 chassis Tamiya has ever made. Luckily there are a few people at my local club that are interested in running a F1 class so maybe we can get a few races in.. 

My friend and fellow TRF racer Dominik Ruf has been racing his TRF104 to great effect. Here is a set-up that I will be using for the next run of the chassis. 

So, in summary, the Tamiya TRF104 is a fantastic chassis and, for me, comfortably Tamiya’s best F1 racer to date. Even on its very first proper outing in a class I haven’t raced for years, the car immediately showed just how much potential it has.

The biggest takeaway was just how easy it is to drive. The rear end has huge stability and traction, which made it incredibly forgiving and confidence-inspiring straight away. In many ways that’s a huge strength, because the car feels planted and consistent, but on the flip side it also highlighted how critical setup is. On high-grip foam tyres it was simply too locked down in the corners, and I was leaving a lot of time on the table waiting for the car to rotate.

That’s actually the exciting part, because despite being underpowered with my old 21.5 motor and never really getting enough time between rounds to chase the setup properly, the chassis still delivered a solid result and felt like it had much more pace in hand. It never once felt nervous or difficult, quite the opposite. It felt like a proper top-level race chassis that simply needs more track time to unlock.

And that competitiveness is already proven. Dominik recently raced his at the ETS and secured a place in the A-Final, which says everything you need to know about the platform’s outright speed when it’s dialled in.

Looking at what some other manufacturers offer, a gear differential or spool could be an interesting future option part. That said, with the Exotek axle bearing kit already allowing compatibility with other manufacturers’ parts, there’s already plenty of scope to experiment if needed.

Honestly though, I still think the biggest gains are in the setup rather than the hardware. More front bite, a freer rear, and better motor performance would likely transform the car, because the base platform itself feels excellent.

The real frustration is less about the chassis and more about the class in the UK. F1 remains such a brilliant category to race, but with so little regular club support it’s hard to justify the time needed to really optimise a car like this. That’s a shame, because the TRF104 feels like a chassis that deserves proper development time.

Until I can find more opportunities to run it, at least it looks absolutely superb sitting on the shelf, and it definitely leaves me wanting another go.

Editable set-up sheet via Petit Rc here (click link)

Manual download here (Click Link)