TRF201XMW – The build – Completed! And first race report…

I mentioned earlier that fitting the electrics and painting the body takes me a long time, so there are not so many pictures here because there is not much to say, but it was several hours work for me to get from the rolling chassis to the finished car!

The first couple of steps in Bag E are fitting the motor and servo. The motor mount doesn’t have a very large range of gearing options, with a maximum of a 24T pinion to mesh with the kit 79T spur, and Tamiya’s only option is a 77T spur. I suspect that B4 spurs will fit. The motor cover doesn’t give much space for the pinion either. The gearing options are fine for a modified motor (I run an 8.5) but might need some thought to get a good ratio for stock motors (which are not generally run in the UK with buggies). Tamiya supply two lengths of screw to mount the motor with, I used the 8mm ones, just make sure that they don’t make contact with the internal parts of the motor when tightened.

The gear cover does not have a great deal of room under it for a big pinion
The gear cover does not have a great deal of room under it for a big pinion

Next step is fitting the servo. I treated myself to a new low-profile Futaba BLS551 – and it was a good thing that I did as there is no way I could have got my (large) electrics in with a standard servo! While I was trying to set the servo up, I realised I wasn’t happy with the standard installation. The main issue was not being to get full lock even at 120% EPA (the maximum with a Futaba radio). This is a problem I have run into quite often. So, I made a few modifications. I won’t share them right now, but when I have a solution I’m totally happy with, I’ll post an update.

Initial servo installation - but I have made some changes since then...
Initial servo installation – but I have made some changes since then…

Last jobs are getting the electrics in and fitting the body.

I’ll talk about the body first. It’s low and narrow with a mid-cab design and a “Le Mans”-style fin. Not a bad looker overall. But it doesn’t give you much room for the wiring, perhaps because it is from the older XR (the sticker sheet is also from the older cars). Read the manual carefully when cutting it out, as part of the rear needs to be left to cover the motor.

No XMW stickers here! Have to make do with the stickers from the XR and XM conversions.
No XMW stickers here! Have to make do with the stickers from the XR and XM conversions.

In order to fit the body, I chose to run the wires off the side of the ESC and along the side guard. They then need to  be stacked vertically along the rear battery post and onto the motor (I use a Speed Passion 8.5 which has the plugs on the end). My original wiring took the wires over the top of the battery post but there is not enough room. There isn’t a great deal of room for the front battery connector either – I use low-profile connectors with the wire coming out of the side and it still rubs on the body. It may be possible to run the wires right down the middle of the car instead, but it wouldn’t look quite so neat. Because my ESC and receiver are quite big, the unused hole in the side guard got in the way of taping them to the chassis. My solution was simply to fit a double layer of tape to lift the electrics up, this worked well and may also help with shock absorption!

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The first race

First race was at an indoor multi-surface track. I chose to go with the kit settings (which I didn’t expect would be suitable but you have to start somewhere), Yellow Schumacher LP Cut Staggers on the front and Yellow Schumacher Minipins with the U6734 insert on the back, mounted on Associated wheels (yes, they came straight off my B4!). Ride height was 21mm all round. Gearing was 23/79.

I also checked the weight distribution. Out of the box with no extra ballast, there was a really good balance from left to right (only about ten grams in it), with about 600gms on the front axle and 1000gms on the rear axle, giving a weight distribution of 37.5F/62.5R at 1600gms. This compares to 34/66 at 1600gms on the B4 with the same tyres and around 40 grams ballast on the front axle. A big difference!

On the scales - 37.5F/62.5R - a big difference compared to the rear motor B4.
On the scales – 37.5F/62.5R – a big difference compared to the rear motor B4.

On track, the car was very, very good, which took me by surprise. In the first round the tail was a bit lively on the slippy sections, but as the grip came up and I got my eye in, that stopped being an issue. Jumping was really good, the landings were really plush, and the balance through the corners was good, albeit with a little mid-corner understeer on the tight hairpins. I leaned the front shocks in one hole to try and address this and it seemed to make a small improvement. The motor seemed to lack a little rip at the bottom end, so I increased the punch on the ESC. Overall, a real pleasure to drive.

The car did go a bit funny at the start of the third round and started spinning unexpectedly in some corners. I thought at first that it may have been the diff or my sensor wire. The car improved after a minute or so, which coincided with a lump of stringy fluff coming of the back end of the car… I checked the gear diff after the race and it hadn’t lost any fluid, and the sensor wire was secure, so I think the bad handling was simply down to picking up the debris.

I was rewarded with a grid position at the back of the A-final, and after a really close and fair race I managed to finish in third place. Hard to say how much quicker the car was over a single lap than the old B4, but it was definitely easier to be consistent. Whereas with the B4 I would have to work hard for 5 minutes to keep it going in the direction I wanted it to, invariably resulting in a couple of costly mistakes per run, the 201 was much easier to drive, and I could have my 10-lap consistency within a couple of tenths of my fastest lap. This is much closer to what I can do with a touring car and very satisfying!

I’ve ordered a few tuning parts (don’t you always?) so I can replicate Satoshi Maezumi’s high-grip setup (if I want to), and I can also try a few changes to the kit setup to get a bit more steering. I’ll keep you posted as things develop, but it has been a very good start!

Dave

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What DOESN’T work in the TRF201XMW…

Square LiPo packs.

They won’t drop in to the chassis due to the rear brace.

And the plugs are obscured by the battery strap.

Stick with saddles!

Square pack - it might look neater, but you can't get it in and you can't reach the plugs.
Square pack – it might look neater, but you can’t get it in and you can’t reach the plugs.

Tamiya TRF201XMW – The build – Part 4

Next up is Bag D, which contains the shocks.

Tamiya are known for making the best shocks in the business and these big bore dampers are no exception. The materials and finish are exceptional. Low friction coatings and alloy caps and spring retainers are a standard feature.

The shocks themselves are straightforward to assemble although there are a lot of shims and spacers that need to be put in the right order so follow the instructions carefully. The dampers come with 2 x 1.7mm hole pistons for the rear and 2 x 1.6mm hole pistons for the front.

Several different shims and spacers needed here. Blue o-rings are used.
Several different shims and spacers needed here. Blue o-rings are used.

Setting the shocks to the correct length for your setup will be more time consuming.

As standard, the shocks have no internal or external limiters. On the front, this gives maxiumum travel when fitted in the outside hole on the wishbone – any longer, and the steering uprights would catch on the arm at full lock. On the rear, this gives enormous downtravel when fitted to the kit recommended inside hole on the wishbone (although nothing binds up), but there is too much uptravel and the driveshaft will catch on the outdrive. My solution is to fit a black rubber o-ring on the shock shaft to act as a bump stop (use the kind you buy in a DIY store instead of the soft silicone ones). This is just enough to stop the driveshaft catching and should stop any unwanted damage. I’ve got a feeling that the kit setup is aimed more at dirt tracks and that there is a lot more fiddling with shock travel to come – Satoshi Maezumi’s high-grip setup uses very different shock positions and limiters from the kit.

One black o-ring on the rear shock shaft as a bump stop
One black o-ring on the rear shock shaft as a bump stop

The biggest problem people have with the aeration dampers used on most buggies now is how to fill them. I’ll share my method. The first thing to remember is that these shocks NEED air in them – a squeak is not just normal, it is desirable. The reason why you need the air is because as the shaft is compressed into the shock, it decreases the volume available for the oil inside the shock. Since the oil is effectively incompressible, and air is relatively easily compressible, you need just enough air to compensate for the shock shaft. Simple physics really. What I have seen a lot of people try and do in the past is build them without air, and then complain when they leak or blow the caps off after a jump – again, simple physics, the oil had to go somewhere!

What you are looking for is a shock that has smooth damping throughout its stroke, with as small a “squeak” as possible. If the damper locks up towards the top of the stroke, you have too much oil. If it squeaks a lot and the piston feels like it has lost damping, there is too much air in there. It is a balancing act, based on experience as much as anything else, although Tamiya do include bleed screws in the caps which makes the process a little easier. Having said that, sometimes I end up taking the whole cap off anyway to get the feel I want.

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The final point of confusion is the springs. Tamiya never publish rates, just colour codes, so it can be hard to compare from brand to brand. To add to the uncertainty, Tamiya seem to have included a “yellow” rear spring that is the same as the “blue” in the Big Bore spring set (#54508), and the front spring is not from the #54507 spring set as the manual suggests (it’s either from #54506 or a special part). The only explanation I have for this is that Tamiya seem to be changing the meaning of “yellow” from medium to hard, as with the TRF418. So, using this spring rate calculator I have put together a list of approximate rates –TRF Big Bore Spring rates.

And once the shocks are fitted (the aluminium balls in the shock bottoms seem rather tight, hopefully they will bed in), the chassis is more or less completed. Next job is the electrics…

After Bag D...
After Bag D…

Tamiya TRF201XMW – The build – Part 3

Bag C is the next to be tackled, and it mostly deals with the front end.

This is possibly the first time in the build that you are reminded of just how much the original 201 was inspired by the Associated B4. The steering and front suspension geometry are more or less a metric facsimile of the American original… and who can blame Tamiya for copying it? The front end of the B4 really is one of the finest pieces of RC car design I have ever seen, and you end up with a durable front end that rides the bumps brilliantly, steers like a demon and suffers from no bumpsteer.

Tamiya’s parts are much better quality than the Associated parts I have seen since the Thunder Tiger takeover, and everything on the front end goes together perfectly – with a couple of small exceptions. Firstly, the front arms are a little tight. Tamiya suggest removing some material, but it feels to me that the friction will go away after the shakedown run so I have left them alone. They also ask you to drill out a couple of holes in the arms to 3mm (another Dremel job). Secondly, the small cross head screws that hold the suspension pins in place don’t look like they would stand up to many rebuilds (don’t forget to use a JIS pattern screwdriver, NOT a Phillips!). It would be nice to have some hex screws here. I also chose to fit the optional front axles (#54220) that will let me use Associated front wheels. Pay close attention to their orientation as they are not symmetrical.

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All that is really left to do is the shocks, electrics and body. The last two take me longer than anything else, but the rolling chassis should be completed very soon!

Tamiya TRF201XMW – The build – Part 2

There is a small bit of extra work to do to the gearbox before it gets fitted to the chassis, and that is assembling the slipper clutch. Tamiya include a 79T 48dp spur gear which is placed between two dark grey slipper pads and two aluminium slipper plates, then clamped down with a chunky slipper spring. This spring is much larger than the spring that was fitted to my old Durga, and comes with two aluminium spacers to keep it clear of the slipper shaft. Tamiya’s suggested setting is 1.5mm, we’ll see how close that is after a few runs.

Slipper and spur fitted
Slipper and spur fitted

The rear shock tower is a really chunky piece, 4mm thick, and after a few bits of hardware are fitted, it is ready to go on to the aluminium gearbox, helped by a couple of substantial pegs which should stop it moving around. The camber link holes overlap one another, which hopefully won’t prove to be a weakness. The camber links use steel turnbuckles for durability, and the ball studs are steel as well. The wing mounts are from the TRF201 and are apparently weaker than the ones from the 4wd buggies.  The tower is drilled for either. There a quite a few screws of subtly different lengths needed here and I must confess to getting in a right mess the first time I put it together, so take your time!

Rear tower and hardware fitted
Rear tower and hardware fitted

The chassis is very nicely finished (as you would expect) with a champagne-gold finish, careful machining to reduce weight, and a few intricate bends to make sure everything is in the right place. Not only is there a kick-up at the front, but there is also a step at the rear under the gearbox. At 3mm thick, it is very stiff, and shows no sign of flexing in the hand.

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At this point, you start to get that “prototype” feel that makes TRF’s so special. Although the side guards on the chassis are plastic, they are machined rather than moulded, as are a few of the other parts. It makes the car feel like an authentic limited edition. The detail on the aluminium posts is also fantastic, with small notches to make sure the parts locate positively into the chassis and the uniform glow of the blue anodising.

Posts and side guards fitted
Posts and side guards fitted

The rear of the chassis is one area where it starts to get a bit fiddly though, with a lot of extra spacers needed to make everything line up. It would have been nice to have a couple of custom parts in this area instead. Nonetheless, it works, although I don’t look forward to taking it apart at the track. For the metal-to-metal connections through the chassis I’ve been using a dab of the Tamiya AG threadlock to stop parts shaking loose.

A few too many spacers required here, all too easy to drop on the floor when rebuilding
A few too many spacers required here, all too easy to drop on the floor when rebuilding

The rear suspension arms are from the DB01, with hubs from the XV-01, and a small amount of material needs to be ground away to stop them fouling the diff outdrives at full compression (After the photo was taken, I used my Dremel with a small sanding drum to create a millimetre of so of extra clearance). I used a little of the Mugen Super Grease to lubricate the suspension balls. The suspension mounts give plenty of scope for adjustment (with optional shims and parts), but are a bit fiddly to line up. The buggy also comes fitted with a comical plastic “bumper” which won’t do much in the event of a crash!

Rear suspension in its mounts
Rear suspension in its mounts
Rear bumper. Wrench gives you an idea of the size!
Rear bumper. Wrench gives you an idea of the size!

Final step in Bag B is to build the driveshafts (which use clips instead of grub screws to hold the pin in place – a vast improvement), put them in the hubs and fit the camber links. Interestingly, Tamiya suggest a specific orientation for the clips, which might have something to do with stopping them from loosening up under power. Again, I use the Mugen Super Grease as a lubricant instead of Tamiya’s light ceramic grease.

TRF201XMW driveshafts
TRF201XMW driveshafts
Rear end mostly complete!
Rear end mostly complete!

And that is the end of Bag B – and the end of this instalment of my build blog.

Dave

Tamiya TRF201XMW – The build – Part 1

So my new 2wd is a Tamiya… which makes me the proud owner of a full fleet of Tamiya’s for my racing exploits!

As you may already know the TRF201 originally came out in 2010 and was basically a Tamiya-ised copy of the Associated B4. Over the past few years, 2wd cars have changed dramatically, and this “XMW” version contains all those developments in one kit… mid-motor; long wheebase aluminium chassis; gear differential; big-bore shocks…

XMW stands for eXperimental Midship Worlds or something along those lines, the Japanese having turned abbreviations of the English language into an art form (remember the”Midship Runabout 2 seater” made by Toyota?).

The box is, as you would expect from recent limited-edition Tamiya’s, a generic TRF box with a special paper label…

The first thing you see...
The first thing you see…

Inside the box is a big pile of bags. The days of blister packs are long gone. Doesn’t make the slightest difference to the performance of the car though…

All bagged up (for the time being)
All bagged up (for the time being)

First step is to build the diff. Well, diffs, as you get the option of both ball and gear diffs in the kit. Handy.

The ball diff is built first. Took me a while to remember how to put these together, but it is simply a case of degreasing the balls and plates with lighter fluid and using the right greases – I don’t use the ones supplied by Tamiya, preferring Much-More diff grease for the main balls and Mugen Super Grease for the thrust assembly.

Much-More silicone diff grease on the main balls...
Much-More silicone diff grease on the main balls…
Mugen Super Grease packing out the thrust
Mugen Super Grease packing out the thrust

The parts are the usual Tamiya quality, perfect fit and finish making for a very smooth diff from the outset, with steel outdrives for strength. The blue anodised diff nut is very pretty! There are often complaints about the steel balls that Tamiya (and many other manufacturers) supply for the diffs but personally speaking I get a good life out of them (most of the time) and they are cheap to replace. As ever, starting setting is hand-tight and backed off 1/8th of a turn.

The gear diff is also very straightforward to build – but having built Tamiya gear diffs before, I knew that the standard black o-rings would not be worth using. They leak like crazy. The red TRF o-rings (#42259) should be considered an essential upgrade – coat them in silicone oil before fitting. On the TRF418, the outdrives needed re-shimming after fitting the red o-rings, but on this diff the fit is still good with no binding. Carefully remove any flash from the internal gears (the plastic ones comes as standard) but DON’T sand them down, and work the diff well as you fill it to get the oil into all the nooks and crannies (Tamiya supply their own #5000 oil, I chose to use Fastrax #5000 oil so I can make changes within the same brand). Slimming freaks will be interested to know that the completed ball diff is 35gms whereas the gear diff is just 22gms.

Check the cross pins behind the gears to make sure the diff is well filled.
Check the cross pins behind the gears to make sure the diff is well filled.

With two diffs built, it is time to build up the idlers and the slipper shaft. This job is easy enough, but Tamiya have chosen to supply the car with their fibreglass-shielded bearings. These are very free running but offer virtually no protection from the elements. My car will spend a lot of its life indoors but I suspect that even dry outdoor running will kill the bearings quickly. I’ll be ordering some rubber-sealed ones as backup.

Ready for assembly.
Ready for assembly.

The gearbox housing itself is a real work of art. Delicately machined from aluminium, and exceptionally light, the black anodising conceals how trick this part really is. Everything fits perfectly inside (naturally), with a dab of silicone grease to soak up some of the noise (the diff will leak silicone at some point anyway, so I always use the same inside a gearbox – never the ceramic grease Tamiya suggest). Once it is put together (with a few titanium screws to maintain the sense of luxury), you’re at the end of Bag A – and that’s where the first part of my build ends too.

The completed gearbox. Stunning.
The completed gearbox. Stunning.