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TOPIC: 2x Thunder Dragons - the good & the ugly

2x Thunder Dragons - the good & the ugly 7 years 1 month ago #14033

For anyone that knows my likes & dislikes, this one is going to be somewhat confusing!

I REALLY don't like Thundershots, Thunder Dragons, Fire Dragons etc etc, anything on that chassis, or anything similarly "Whizzy" looking. They're fraught with design flaws & are hugely fragile.
HOWEVER, after rebuilding the first of these 2x cars, I have to admit I did enjoy myself...
For anyone out there who hasn't had the (mis)fortune to own one, I'd suggest it might be worth getting one purely for the sake of rebuilding it.

There are quite a few good yet simple design features in it, which are overclouded by the fairly major problems with it, but when you find these "nice" bits, it can be quite pleasing.
Another thing it has going for it is the part-count & less than mind-numbingly simple way the build manual presents itself. There are enough bits & just enough complexity to keep you awake & interested, which is good, if like me, you enjoy the "putting together" bit of owning a Tamiya.
If you buy one purely to play with, forget it, you'll be on the tamazepam within 24hrs.

So then, what on earth was I thinking to actually pay someone to acquire said beasties?
I've been looking for a sensibly priced RC buggy for my nephew, & these came up cheap.
Plan is, build a bitza-runner for my nephew, & a tidy complete one to sell, to recoupe the cost of the project.

Below should be a pic of what arrived for sub-20quid


As you can see, one is in much better shape than the other, so the rebuild(s) will start with that. At this point the plan was to rob any missing bits on the posh one, from the tatty one, then make/steal/beg/borrow to turn the remains of the tatty one into a fairly presentable runner, perhaps addressing the design flaws at the same time.

Ok, lets get started then! Strip & assess condition of parts




I was gobsmacked to find the troublesome A5 part, & the suspension mounting lugs on the gearcases in good condition! Didn't expect that at all!

After stripping the gearboxes, there was a story emerging...
The gears were clean & unworn. The aluminium motor pinion was also unworn. It still had all of its original plastic bearings, again, unworn.
I poked about further, & on the face of it, it appeared the only damage to the underside was a small scratch to the underside of the bumper!
Perhaps I could show up the rest of the expected damage with a good wash in the trusty sub-sonic cleaner (The sink)


There we go, all clean & shiny!
Do some more inpection.... nothing, no cracks, no scuffs, no bent bits, nothing, other than the aforementioned scratch in the bumper!
What gives?! There's no way I'm this lucky, maybe there'll be something horrendous in the gearbox to make up for it? I'll clean those bits next (In central heating fuel, to get rind of any old grease)


Nope, nothing wrong in there either!
In fact, looking at the ends of the driveshafts & the slots in the drive cups, there's absolutely no wear... a few of the driveshaft ends even still have their original black coating still intact!




Ok then, I noticed there were some splodges of gold paint on the otherwise unpainted bodyshell. I'll move on to cleaning that up then.
I probably spent an hour trying to figure out the best way to give the shell some brake fluid treatment without upsetting the (Original) decals, which appeared to also be in good condition.
I needn't have bothered - I picked the shell up & flexed it a bit, & was showered in shards of gold! Paint's not stuck then... The rest of it came off easily with some thumbnail rubbing! A quick splosh in the sink to get rid of any leftover gold flakes, & TADA, one clean, undamaged, unpainted Thunder Dragon body!

As much as I wanted to find things to whine about &/or repair, there was just nothing to do on this car. Everything was as it should be. The fasteners were all undamaged, the right ones in the right places, even the remains of any sprue had already been carefully trimmed!
Was it a resto/rebuilt one I had? Could it really be that it had only been run once, maybe twice? The condition of all the "wearing" parts certainly suggested so!

Sorry this one has been so dull so far... Here it is then, finished, ready for Ebay!



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Re: 2x Thunder Dragons - the good & the ugly 7 years 1 month ago #14038

Glad you enjoyed the rebuild. Just out of curiosity, other than the A5 part, what have you found frail about the Thundershot chassis? I always kinda liked the old school high ground clearance style of the chassis. The design is somewhat interesting. Tamiya had to replace the aging Hot Shot chassis cars with a simplier, less-expensive design that had to be competitive until the arrival of the Avante. I think they suceeded. Since I haven't run one hard, what kind of things should I look out for weakness-wise? Thanks.

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Re: 2x Thunder Dragons - the good & the ugly 7 years 1 month ago #14039

The resto of the first car took from Friday evening, to Sunday night... SMOOTH!

I picked up the second car tonight, for a quick look over & say "Hmmm"





This was more like what I was expecting from the first one, but with some extra unexpected "horrors"
Strip & inspect to see what's what, what shouldn't be, & what isn't


First thing that shouldn't be, was the bent front bumper - I'm hoping the heat gun might sort that out, perhaps even a hot bath might cure it...


Shocks were... EEEuuuwww!


No idea what this is about... perhaps the proper one is lurking somewhere else? (Wrong pivot pin)


Upon stripping the gearboxes I located some more eeeuuuwwww, a combination of Tsmiya moly & Castrol LM grease, I think.
I was fairly pleased to have found ballraces in the hubs, & half expected the gearboxes to be ballraced too, but no. Never mind.


Wheels are going to cause me a headache.
Yep, they're Hotshot, not so bad (Tyres are still easily sourced for those).
Ah... all 4x are fronts....
Ah (some more) tyres are all split, perished, flatted & fubar.
What do I do here? Look for second hand Hotshot rear wheels, to make a set, then a set of new tyres to suit? Try to source the proper wheels/tyres? Look at some sensibly priced replacements of a different variety? Say "Hmm" some more....


The rest of it is still soaking in hot soapy water. I'd better finish cleaning that lot, have a shower & get to bed I think. Perhaps do some more tomorrow...

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Re: 2x Thunder Dragons - the good & the ugly 7 years 1 month ago #14041

Nice thread, eddrick. Always a pleasant read - and this one even has lots of pictures! ;) :y:
Lucky first Dragon, trouble on the second I see...

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Re: 2x Thunder Dragons - the good & the ugly 7 years 1 month ago #14042

Well, there's the obvious A5 part, but also its equivalent at the rear.
The other bits that split are the lugs on the gearboxes that hold the suspension arms.
Problem is, the plastic of these (A) parts seems to be relatively hard & brittle, much more so than the more commonly used ABS parts of other models. One could be forgiven for suspecting it may be some kind of acrylic, going by feel & nature of the material.

The problem isn't so much fragility during running, it's more to do with the nature of the material, the amount of "meat" around the pivot holes, & the coarse/sharp threads of the pivot pins themselves.
I think what happens is: due to the non-ductile nature of the plastic, the screws don't cut into it properly, & try to enlarge the holes, causing lots of stress around the holes. Then, with even a minor hit, the plastic splits at the weakest point. Almost like setting a "hair-trigger".

Thinking about it, the way to avoid or rather lessen the problem, would probably be to heat the screw before carefully screwing it home, the very first time.
The screw would need to be hot enough to properly "cut" a thread into the hard/brittle plastic. Also, you should stop trying to turn the screw, before it's totally seated, so as not to impart further stress.

If you're running one of these, you really need to avoid even the lightest impact to any of the 4x wheels, as hitting at these points has the maximum leverage on the weak pivot point.

The gearbox-to-chassis mounts are also prone to the same thing, particularly the front upper & rear lowest mounts - again, a relatively minor crash can rip these portions out of the main chassis (The front of my tatty rebuild is like it, so there will be a pic shortly to show what I mean).

If Mr Tamiya had made the entire car, or at least A-parts out of the same material as the suspension arms/links, I suspect these cars would be nearly indestructable, which kinda begs the question "Why didn't you?".
Even making the just the pivot points separately bolt-on,out of a more resilient material would've been a vast improvement.

Another relatively weak point is the rear of the chassis, where it forms a "bridge" over the top of the gearbox, & holds the rear body mounts - same problem as the CC01 chassis, where if it gets hit hard or falls upside-down, it can result in cracks/breakage of this portion. Come to think of it, the Wild Willy & Quattro etc, also suffered from this

Another thing to watch is the position of the motor pinion on the motor shaft - you either need the special tool or careful measurement to get this right, as there's no way to see whether or not the pinion is engaging properly with the spur gear. Incorrect position will result in stripping the spur. Again, this has happened with my tatty car, so I'll post a pic.

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Re: 2x Thunder Dragons - the good & the ugly 7 years 1 month ago #14043

Cheers Edou, I made a special effort to take more pics!
It's not all bad having the second car in such a state, it's more photo opportunities!
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Re: 2x Thunder Dragons - the good & the ugly 7 years 1 month ago #14049

A set of Hotshot tyres & new rear wheels aren't going to be a cheap option ... I reckon over 40 GBP :cry:

What about converting to 12mm hex hubs? I found these wheels on eBay for 10 GBP :)
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Re: 2x Thunder Dragons - the good & the ugly 7 years 1 month ago #14068

Yep, I kinda expected something like that!

More "Hmmm" to confuse matters further - whilst having a measure of the wheels to get some idea of "sensible size" for aftermarket replacements, I noticed that the 6x(?) driving pips on the backs of the wheels have been removed. The fact that the black paint fell off in the bath with no effort was a mark "to keep", discovery of chewed rims was a counter-mark.

I've spent all evening on Ebay trying to find either a set of 4x wheels & tyres of similar size to the originals, OR just 4x tyres that would fit the rims I already have. Task was seriously hampered by lack of info on the sellers' part - I don't get it, how do people buy (Or expect to sell) wheels/tyres without either specifying what they're for, or worse still, what size they are?!
I think I'm gonna give up with the "convenience" of the 'net, grab a wheel & go tyre-hunting in proper shops instead.

Not too worried about drive-method at this point. Yep, 12mm hex converters is a simple & sensible way to go, but I'll wait until I know what cheap wheels I'll end up with before committing myself - eg if I end up with dish-wheels, they'll probably end up on the mill to be made more "posh-looking", so I could just make the wheels fit the original adaptors whilst I was at it.

So far, all I've achieved today is to find out that High-lift tyres fit Hotshot rims, but they look too big for the body I intend to use (& they'd cow the gearing up)

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Re: 2x Thunder Dragons - the good & the ugly 7 years 1 month ago #14069

Yep, finding tyre specs (and matching them) is usually quite dramatic. Got enough tyres and rims to prove it. :S
I think Towerhobbies and Seidel are the only sellers giving any decent info...

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Re: 2x Thunder Dragons - the good & the ugly 7 years 1 month ago #14073

Yes Edou, nightmare.... BlacksmithProducts list sizes, but you can never be sure what the measurements are referring to - there's an awful lot of different numbers seeing as in theory there's only 1.9, 2.2, 3.3 etc standard wheel sizes.

Anyway.... just had the cam out for Saito, to capture some splittage-de-thundertatos.
Typical 'shot spitting points (& other hilarity)-

Front top chassis/gearbox mounts (Note also the white stress mark where this one's obviously had a bit of a hard front-end hit)



Rear chassis/gearbox mounting points (Split mid-mount is usually upside-down-driving related)



Splits occur in ALL suspension mounts, wherever screw-pins screw into the harder-grade plastic



& I'll add this pic just cos this sort of thing always makes me giggle - overcurrent/short or soldering iron? Perhaps it wasn't a Thunder Dragon, maybe it was a FIRE Dragon!

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