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Re: 2x Thunder Dragons - the good & the ugly 11 years 5 months ago #14171

Considerable progress tonight!

Stripped & rebuilt the dampers. Note the tub-full of yak that was in them. Also note the bent damper rod (Middle one). This was straightened using my normal method - put it in the lathe chuck & tighten it just enough that I can only just slide the rod through the chuck jaws. Then, slide the rod in until it "sticks", ie the bend reaches the jaws. Tighten the chuck, then rotate the chuck so the bent bit of the rod is facing towards you. Wind in the cross slide to bend it until it lokks straight, then rotate the chuck a few times to make sure it is straight, & if not, repeat the process until it is! Also handy for straightening bent bike spindles...

Also lopped a bit off that odd overlong screw-pin. I say odd, the length didn't match either of the 2x sizes that come with the kit, so no idea what that used to belong to!



Rubber sealed 1150 ballraces turned up this morning too, so I got the front & rear gearboxes assembled this evening too. Rubber sealed bearings were fitted where they need to keep the locals out, normal ballraces fitted internally. As my previous post, I then had them to bits again to replace the bevel "thrust bearings" with 1150 ballraces too.

Repaired the busted front chassis lug with polyester resin, just to give a "flat landing" for the gearbox pillar that butts up to it. I'll daub it with black printer ink once it's properly set, to blend it in with the rest of the chassis colour.



Hopefully the Tx & Rx (Futaba Attack) will turn up later, & I can move onto modifying servos to be waterproof & make up a MSC deck
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Re: 2x Thunder Dragons - the good & the ugly 11 years 5 months ago #14182

I used rubber shielded bearings, but only in the normal places the manual suggest. I'm sorry, I should have been more specific. The gears in the Fire Dragon re-re were bad from new. The replacement Thundershot gears (Same as Fire Dragon) were new on the spur and also deformed. Removing the prop shaft stopped the noise which led me to examine the bevel gears more closely. I too, always found it somewhat annoying Tamiya molded suspension mounts right into the gearcases/chassis etc. instead of a separate block. I've read adding adjustable upper links using "rod ends" takes stress off the upper mounts at least in a crash.

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Re: 2x Thunder Dragons - the good & the ugly 11 years 5 months ago #14211

Ahh, in that case I'd suggest it's the material they used for the re-re gears (Mine have all been original release ones).
Are the gears deformed when new? If not, try replacing the "Thrust bearing" components with a proper ballrace, to see if that stops/delays the problem - it's likely to be heat related.

As a likely cause as to why the re-re is a problem, I would guess it's down to the material density of the gears - as a cost-saving exercise, it is possible to fill the injection-mould cavities with a reduced "charge" of molten plastic, which leads to the finished moulding being everso slightly contaminated with minute air bubbles. A "normal" charge would keep the plastic pressurised until cooled/set, which squeezes this air out. - the way to prove this would be to compare an original gear with a re-re one, by weighing it. If this is the case, the re-re one will be slightly lighter.

Incidentally, this "cost-saving" technique is usually the main cause for the brittleness of Chinese/Taiwanese I/M plastic parts. The other cause is overheating the melt to get a faster cycle time from the I/M machines, again for cost-savings.

I know I've been moaning about the rubbish design of the screw-pins, suspension links, integral mounting lugs on the gearboxes etc, but the fundamental problem is material choice. It's just too hard to be using self-tapping screws with such coarse threads in it. There wouldn't be a problem is the parts were all made from the softer plastic that the blue parts are made from. Kinda makes you wonder if that was done on purpose to increase aftermarket/spares sales.
As I said earlier, as much as I don't like these cars, there are some really good ideas in them, & it's really only the multiple cracking points that lets it down.

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Re: 2x Thunder Dragons - the good & the ugly 11 years 5 months ago #14212

Anyway.... I ate too much for tea & I'm too uncomfortable to sleep now, so I thought I'd just do a quick update as to what I've been up to today....

Radio turned up. After a quick check to make sure it was working properly, I set about cleaning it & modifying for use by a small child. Below is a pic of "How it arrived"



The "grubby" was well set & wasn't going to come off easily, so I decided to strip it so I could give the case a proper bath. I also needed to investigate a clattery aerial, which I was sure would cause interference problems (27MHzAM is prone to any metal-on-metal generated interference).

Note the 2-pole style wiring on the power switch (ie red to 1 set of switch contacts, black to the other set, so that you control +ve & -ve at the same time). Although this is good electrical practice, it's not necessary & can pose a problem if damp or corrosion gets in the switch - normally, the -ve would be direct-wired, only he +ve goes through the switch, added to which, BOTH poles of the switch are joined to do the switching, ie if one fails, the other takes over & stops you losing radio contact.

Also note the chip at the top-left of the board - this is the MSL9362 chip I keep banging on about. It has 4 digital proportional channels on-board, but only 2 are ever used with these cheapy 2-channel transmitter boards. It's usually very easy to convert transmitters using this chip, to 3 or 4 channel. They're also used in Acoms Techniplus Alpha, & Traxxas TQ3 transmitters, among others.



Whilst I was waiting for the case to dry, post-bath, I thought it would be a good idea to make the throttle trim tab less easy to knock/move - how many times have you handed your tranny to a friend saying "here, have a go if you want to", only to watch them crash flat-out into the nearest obstacle... then when you get the tranny back, find they've inadvertently moved the trim to full-forward? The new owner of this car is a small child, so I suspect the whole "trim-shifting" thing might be a problem, hence the mod



All clean & posh!

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Re: 2x Thunder Dragons - the good & the ugly 11 years 5 months ago #14229

Good as new! :cheer:
What did you do to the trim exactly? Trim the switch a bit?

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Re: 2x Thunder Dragons - the good & the ugly 11 years 5 months ago #14272

Yeah, took the trim lever out (So I didn't damage anything else during the operation) & cut just enough off the top of it so it doesn't sit proud of the case any more. It's still accessible if you need to use it, but a lot less likely to get inadvertently adjusted during excitable throttle usage.

Been making the MSC deck tonight, will post some pics when there's something worth showing.

Still no wheels/tyres, still having mental issues over that subject! - can't decide whether to go for proper-size wheels to save gearbox modding effort, & use the pickup body that I really wanted to keep (Plus it needs painting & I haven't got any suitable paint), OR use a spare pre-painted HSP Bug Crusher body (Which I forgot I had) & put big wheels on it to make it look right, & then start down the route of sorting the gearing out beyond the adjustment on the motor plate. I had thought using the Bug shell would be ideal to illustrate it's possibility (Who was it that was talking about putting a VW beetle body on a Thundershot? Can't remember...). Putting big wheels on a 'shot chassis is making me wince just thinking about it!

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Re: 2x Thunder Dragons - the good & the ugly 11 years 5 months ago #14276

Closest thing to it that I could find...

www.hobzob.com/rc/1831

Not too shabby! Doesn't say much about how long it'll stay in one piece of course.

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Last edit: by Edou.

Re: 2x Thunder Dragons - the good & the ugly 11 years 5 months ago #14279

Yep, I like the look & I've got a spare set of modified Dagger wheels/tyres in the loft, BUT, it will seriously cow the gearing up, so I'll either have to hope I can suitably mod the motor plate to fit a much smaller pinion, or stuff a crawler motor in it (To get torque over speed).

Just took a plunge & bought a set of Mardave spikes on dish wheels, which I'm told will fit the Hotshot rims, so I'm gonna try that first, see how it runs, to get a better idea of how much smaller a pinion I'd need for 2.2s & if it would be possible. I'm pretty sure I won't get away with it though - the whole reason I've got those 2.2 wheels & tyres is cos I had to take them off another car that had wonky gearing due to them.

I'm probably also going to have to sleeve the shocks, to reduce suspension travel so the wheels don't foul the body - they're clear of it, but only just.

& as you say, there's the fragility issue to also consider!

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Re: 2x Thunder Dragons - the good & the ugly 11 years 5 months ago #14304

A small amount of progress & hardly worth mentioning, but I'm kinda stuck until some of them raand fings turn up (Apparently they've been dispatched, so hopefully I'll see then by the weekend). Once I've got wheels on, I can run it & make wheel/body/gearing type decisions properly.

Anyway, made up an MSC deck out of plasticard (Was going to do it out of 3mm polypropylene, but decided the shed's too unfriendly at the mo). The M2 screws are just holding the bosses on until the gool sets



I painted it black, & once that was dry, fitted the rest of the RC gear.
The bag on the RX is "waterproofing". I had a look at waterproofing the servos too, but the way these particular ones are constructed doesn't allow for my normal trick of machining an O-ring groove on the output shaft. So, I just took the cases apart, degreased then reassembled with a tiny amount of silicone sealant on the joints & called that good enough. After all, servos are much cheaper nowadays, & in the unlikely event that enough crap gets into it to mash the gears, it'll just be easier to replace the whole servo.



Once I've got some wheels (& decided whether or not it wants bigger ones) I'll be able to pick a body, & move on to making body mounts
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Re: 2x Thunder Dragons - the good & the ugly 11 years 5 months ago #14306

Good evening Eddrick,

i might have some wheels for you from my thundershot and thunderdragon resto's. Wil have to look in my attic if i still have them. I can't acces it right n ow while my wife and son are fast asleep but will do it first thing in the morning.
Will post a pic when i find them, not sure in what state they could be lol :)

Cheers, Bram
Restoring Countach 58005
Restoring 58015 RR
Restoring 58098 F40
Restoring King Cab and Monsterracer
Restoring Audi Quattro rally
Restoring Mk.1 Sand Scorcher
Restoring Porsche 936

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