Tamiya TRF201 Project

Page 4: Resurrecting the Original

   

The picture on the left shows all the parts I had left over after finishing the TRF201 XM.  Apart from the obvious chassis tub, I had a complete set of shocks, a rear shock tower, a gearbox housing, a motor mount, a battery cover, and lots of hex hardware.  It practically looks like a buggy except that all the suspension arms and steering are missing.  How hard could it be to complete the model?  The answer is on the right which shows the majority of the parts I had to buy to complete the model (a few had not arrived yet when the photo was taken).  Many of the parts were reasonably inexpensive, but there were a handful of major exceptions.  Let's get started.


   

Because I couldn't get everything I needed in exactly the way I needed it, I ended up putting a couple of aluminum upgrades on the XM so I could use the stock plastic parts on the regular 201.  The first of these parts were the rear suspension mounts shown on the left.  The 3 degree toe angle these produce is equivalent to stock, but they have that cool blue aluminum look.  I installed them and then reserved the plastic suspension mounts for the other model.


   

Although all of the plastic parts for the servo saver were available, there was a single bit of hardware, the steering post (BB31), that I couldn't find.  Without this it isn't possible to build the steering and it is a custom piece of hardware with no reasonable substitute.  However, if I bought the very expensive aluminum racing steering set for the XM which eliminates the need for that part entirely, then I could take the stock steering parts and use them for the other model.  The picture on the right shows the racing steering installed.  Note that there is no servo saver with this setup.


   

With the necessary parts stolen from the XM, I can now start rebuilding the standard 201.  On the left you can see the steering system installed which I pilfered from the XM.  The next bit I couldn't find available to buy was the front aluminum suspension mount (BB7).  This is just a flat plate with a couple of holes, but you can't build the front suspension without it.  I found the optional weight block set shown to use instead.  This adds 30g of weight over the front wheels for more steering traction and also adds 5 degrees of kickup angle to the front suspension.  I didn't necessarily want either of these features, but it was the only way to get the parts I needed.  The installed result is shown on the right.


   

Another discontinued set of parts was the blue titanium turnbuckles.  I bought the silver titanium parts from 3Racing shown on the left, but I didn't like how they looked since nothing else on the chassis is that color.  I found some black and blue turnbuckles from the DF-03 MS to use instead.  The length is wrong by 1mm but that was no problem since the ends are adjustable.  The result is shown on the right which I think looks much better.


   

Now I had to decide on electronics.  I used a fancy low profile servo on the XM and decided to use a blue anodized ProTek servo on this model mostly because it looks good.  Because I used a Tamiya brushless system in the XM, I thought I would use an old Tamiya racing brushed motor in this one.  I chose the Dyna Run Racing Stock motor (20T) with the maximum size 27T pinion.  It ended up being a really good match for speed and power.  In fact, this model was now faster than the 10.5T brushless XM.


   

I didn't think it was right for the brushed version to be faster than the brushless so I got the smaller 77T spur gear and went up from a 24 tooth to a 28 tooth pinion on the XM.  You can see the difference in size on the right.  Let's do some math to see the gear ratios and theoretical wheel speeds.
So the XM should be about 12% faster than the 201 as built.  The brushless motor is obviously capable of more, but there are no higher gear options available for this transmission.  A spur gear any smaller wouldn't fit the slipper pads and the Tamiya brushless system is not rated for 3s.


   


Now I've got two TRF201's!  It only cost me an arm and a leg and month's worth of life, a price well worth paying.

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