Tamiya TRF420 Tips and tricks - Reliablity

The Tamiya TRF420 Tamiya race chassis has impressed me with how it has constantly delivered. I've beaten some personal bests thanks to its speed and consistency. Over the last few months many TRF racers have been putting it through its paces at the track and we have encountered a wide range of different scenarios so I thought it would be good to cover a few tips and tricks that will help out if you have any issues at the track.

Front Direct Cups.

On a very hard impact you can sometime lose a swing shaft cap. So you need to check these after every run. This will help look after the swing shaft and the spool Cups.

Also over the course of running indoors some of us have had a larger crash (Ahem), which results in the aluminium spool cup ends opening up a little. This is a problem as these will ultimately fail. There are two simple fixes to this.

Method one - Replace the cups, this of course means it could happen again, so Tamiya do make a Steel version (54934), which is much stronger. I've been running 13.5 blinky, so lower winds may still have an impact).

The steel version weighs in at 3.9g this weighs in at 2.1g heavier than the kit part, but it will not bend.

NOTE: Yokomo BD8 spool outdrives also fit if you find yourself stuck. It is important to remember that these are shorter and are more prone to break than the Tamiya part. So only use these if you are unable to get hold of the official Tamiya parts. 

However I would suggest you do the following..

Drive shafts

The kit front double cardan shafts are 44m long. If you swap the Tamiya Drive Shaft for 46mm Double Cardan Joint Set (42230) you will drastically reduce the amount of issues with the drive shaft caps coming off on hard collisions.

Importantly they will massively reduce the chance of the spool cups opening out. All of the TRFUK guys now run the 46mm shafts and we do not encounter any of the reliability problems. The longer shafts do reduce the steering a small amount, but as the TRF420 is almost too agile this is not an issue, especially when running the Bittydesign Hyper or the Zooracing Baybee

Front Hubs

The new TRF420 suspension is a step change from the previous car, and it is safe to say that the C-Hub issue is now resolved. In the seldom event that you do get a breakage at the front it is more likely to be the front upright than the C-hub. So I would suggest you have a set of spares in the pit bag.

The new uprights are not interchangeable as you need to mount the carbon swing arms, so if you find yourself in a situation where you only have one in your spares and it is for the opposite side to the one you have broken then all is not lost.

You just need to mount the carbon part but flip the upright over, and fit an additional 1.5mm of spacers to compensate for the difference in the arm height.

E.G. If I run 2mm of bump steer on the uprights I will need to install 3.5mm on the emergency arm. It is not a perfect solution, but it will work to keep you on track and this tip helped me take the A-Final at a recent event as opposed to an early bath 😊

Tamiya ball joints 

The new Tamiya arms are great, but one annoying thing is that balls that attach the roll bars need a bit of filing down to ensure that they move freely. This is not a big issue when you are at home, but if you are trackside and you have broken an arm it can be a pain to do whilst in the pits. The tightness is down to the new low tolerance Ball connectors, so you can instead use Tamiya 54257 5mm Reinforced Adjuster (Grey/8 Pcs).

You just need to trim them to the same size

Once mounted you will find they work well and the suspension arms will require little or no filing to avoid any binding.

Essential spares

If you want to be prepared, I would consider the following as worthwhile to give you piece of mind.

• Tamiya Tamiya 51639 TRF420 D Parts (Suspension Arms)
• Tamiya 54934 TRF420 Steel Front Direct Cups (2 Pcs.) or Tamiya 51647 TRF420 Aluminium Front Direct Cups (2 Pcs.)
• Tamiya 51641 TRF420 F Parts (4° Hub Carriers)
• Tamiya 51638 TRF420 C-Parts (Front Uprights)
• Tamiya 54921 Reinforced Swing Shaft Caps (Front/Rear, 2 Pcs. Each

I cannot stress enough that running the 46mm shafts is a good thing if you have collisions, outdoors this may not be such an issue, but for the few months of indoor running the switch to 46mm shafts has eliminated the spool cup issue.

I am still discovering more speed with the TRF420, and myself and some of the other TRFUK guys are looking forward to the outdoor season. Before then I will post a set-up soon that has been working well for the  alloy chassis soon.

Thanks to Dan, Steve and Tony and the other TRFUK racers.