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Yalson

Quick Kyosho Raider rebuild

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As in, I hope it won't take long, rather than I hope the car will be fast. I think it is fast, but we'll come to that later.

So, anyone who haunts this non-Tamiya section of TC may have seen my confusion over the steering system on a second-hand Kyosho Raider that I recently bought. The car looked great, had some of the electronics included and on a cursory check seemed to be in pretty good condition throughout. However, the steering was all over the shop, with the front wheels displaying an alarming degree of toe-out.

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Some debate ensued as to why this was, but it was narrowed down to the ball joint on the hubs being inserted into the 'inner' of the two available holes. This not only had a disastrous effect on the car's stance while stationary, but would have also had a similar effect on its steering ability while in motion, as shown by this image of it on full lock.

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So what's the to-do? Well, first of all, have a quick nose around the chassis to see what we can find.

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It's a good-looking little beast, the Raider. Although I was almost exclusively a Kyosho user when I used to race back in the 80s and 90s, I never really warmed to it in period, as by the time it was released I'd moved on to a Mid and Kyosho's entry-level kit was seemingly already too much like a kid's toy to be bothered with. Kids can be such snobs. Here it is, though. I like it already.

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The blue paint looks good (similar to the colour khyzersoze painted his – see link below) and I love the treaded front tyres. I have no idea what posessed Kyosho to make them with such an elaborate tread pattern rather than the conventional longitudinal ribs, but they did and it makes me very happy.

Anyway, this Raider comes with a pretty nice shell, which has been well painted, kept clean and is only showing a little wear around the rear mounting point, as for some reason it has been cut in a square shape rather than a circle. I see no conceivable reason why anyone would do this, as it will inevitably lead to the lexan tearing at the corners of the hole, but someone clearly thought it was a good idea. If you want a graphic demonstration of what happens when you put corners in holes in flat surfaces which are then placed under stress, look no further than the link below. Eventually, the corners rip. In some cases quite spectacularly:
http://www.century-of-flight.net/Aviation history/coming of age/De Havilland Comet.htm

But enough of aeronautical history. What's under the shell? To be honest, I didn't really know until tonight. I knew it had come with an ESC and servo, as these were mentioned in the eBay listing. I knew the servo was an Acoms (which implied I would have to replace it or swap the plug for a Futaba-compliant one) but I knew nothing about the ESC. I knew it had a motor in it, as I had seen it through the side of the shell. 540-sized, exposed brushgear, so probably some sort of mass-produced stocker.

Oh.

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A Tamiya Dyna Run Super Touring. Now I have been away from this hobby for over 20 years, so I am not exactly up on Tamiya's motor output during that time. I know what a Sport-Tuned and a Torque-Tuned are. I know about the Technigold and the Dynatech and the shadowy, mysterious-sounding 'Black Motor', which really isn't as exciting as it sounds. I had no idea what this was. I was still guessing it was a fixed-can stocker of some description, although the timing marks were a little confusing.

Oh. It's a 13x2 modified from 1996. And there's a guy selling a new one in Australia for £100.

https://www.ebay.co.uk/itm/Tamiya-Dyna-Run-Super-Touring-53263-Electric-Motor-NEW/292183947634?hash=item4407853972:g:WvgAAOSwYS9ZarUC

OK. Well that's... unexpected. It's got a piece of Tamiya history in it. But why would you fit a 13x2 in a Raider? I gather they're pretty tough, but you'd be pushing it with something that snarly. I do hope this fearsome museum piece has not reduced the gearbox to mush.

 

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Well, the gearbox feels tight enough diff-wise and it doesn't make any unpleasant whining noises or graunching sounds. It feels... like a Kyosho gearbox. Let's have the cover off to see what it looks like inside.

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Hmm. Seems fine in there. Looks like a 15t pinion meshed nice and firmly to a perfectly good spur gear. It is at this point I realise that in my haste to gather my tools together to start taking the Raider apart I forgot to pick up a Philips screwdriver with a long enough shaft to reach the screws holding the motor in, which is going to rather limit the extent of this evening's preliminary tear-down. Chuffed that the gearbox is looking OK, though. I'd been worried about that since I saw the motor wind.

You can also see the Raider's rather useless plastic driveshafts in this picture. When I was looking at other people's Raider builds on here while I was bidding for this one, I read about these. Obviously I haven't driven this car yet, so I cannot comment from experience on their uselessness, but I took it as read that they were, as having plastic driveshafts is a stupid idea and Kyosho should frankly be ashamed of themselves for issuing them as standard kit in a beginner's model. As a result, the first thing I bought on eBay after winning the Raider was a set of Ultima-type OT-6 steel dogbones to replace the plastic nonsense delivering drive to the rear wheels.

Of course, while I was looking through the old RC spares box just now for something else, I obviously found that I already had a set of OT-6s in one of the drawers, as well as what look like a set of Ultima full driveshafts with UJs, which might do the job even better if they fit.

I'm also now wondering if the plastic driveshafts were that bad if they survived having the power from a 13x2 wrung through them for however long. I may have done Kyosho's designers and accountants a grave disservice.

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What about the electronics, I hear you say? Here they are. Pleasingly, the Acoms servo is not so old that it has the obsolete plug with the retaining hook on it. If it had, it probably would have gone straight into the spares box. Instead, it and the (super-basic) ESC are resplendent with Futaba-compatible plugs, so no worries mating them to a modern receiver. I have already bought radio gear, so it should be a straight install. I am a little concerned about that ESC's capacity to handle a 13x2, though. Although it obviously can do as it shares a car with one. Whatever, I may swap the Tamiya motor out for a much milder 21T brushed one I bought a while back. I am basically building this so I can bash it around the local park with my daughter, so the ability to warp time and alter the Earth's axis will not necessarily be that desirable.

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So it's all looking rather nice. The only issue is that the front of the car still has the stance of a long-lost cousin rushing up to embrace you. This will not stand. Popping the steering rods off the ball joints reveals something rather odd, namely that there doesn't appear to be any way of removing the ball joints. The parts do not have any way of unscrewing them from top or bottom and there is no hex collar to remove them with a spanner. Um, OK. Can I pull them out? No, they are securely fastened, so it seems. It is at this point I discover something slightly alarming, which may be the reason why the ball joints were moved to the inside of the two available holes: they are only screwed in finger tight. I am able to remove them by hand, without any tools, and reinstall them in the outer holes. I am then able to repeat the process in the other direction. Ah. That's not ideal. What I fear has happened is that for whatever reason (possibly repeated removal and reinstallation in an attempt to adjust the stering and make it work properly) the outer holes have become too loose for the threads of the ball ends, meaning that the previous owner has had to move them inboard as a matter of necessity. I doubt it did much driving in this configuration, though, for reasons the earlier picture of it on full lock make obvious. It simply won't turn set up like that. However, I imagine I have access to tools the previous owner may not have done, namely Loctite, some way of sleeving down the holes in the steering arms to retain the ball ends, or simply replacing the hubs altogether. I will not be thwarted by simple mechanics.

Next move is trying to centre the steering, as it seems rather wayward, even when the wheels are facing in approximately the right direction in relation to one another after the ball ends have been moved outboard. The servo saver has clearly been installed off-centre and this is obviously not improving the lock situation. Its better than it was, but still not ideal. So I go about lengthening the rods to equal it up and... the rod end runs out of thread and falls off on the right side. I have already purchased a replacement Tamiya servo saver sprue on the recommendation of TC user Champ85, so this may not be that big a deal once all the new bits are fitted. But is does seem to me that the Raider's stock set-up is inherently compromised. It doesn't have enough lock and the components in the steering sysytem are flimsy and not up to the job. I suspect there will be work at this end before me and the girl can go scaring squirrels. Off to bed now, though.

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Cheers!

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Right, back to this. Daughter had a nap for a couple of hours earlier, so I thought I'd see if I could do some jobs on the Raider. Here it is, looking cheerful.

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Jobs listed for today:

1. Replace the plastic rear driveshafts.

2. Remove the Tamiya motor for possible refurbishment and resale.

3. Look into replacing the useless Kyosho servo saver with the Tamiya one I bought on the suggestion of @Champ85.

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First up, the driveshafts. Easy job, this. Only requires the removal of one screw in the upper suspension link and you can remove all of the required parts. The choice at this point was what to replace the plastic dogbones with, as I had not only bought a NIP pair of steel Ultima shafts, but I'd also found a pair of identical steel shafts and some driveshafts with UJs on them in the old pit box.

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The steel driveshafts in the pit box were probably also Ultima items, as I briefly had one BITD and now desperately wish I hadn't sold it. Although I originally thought that the UJ shafts were also Ultima items, on consideration they are probably Optima Mid front units that happen to be the same length. Let's see if they fit, eh? Total enginering overkill for a backyard basher, but if we've got them then why not?

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The plastic dogbones which came out of the car are in remarkably good condition, considering the motor it has fitted. I am beginning to think that this car was a rarely-used shelf queen, as although some of the parts have clearly seen use (the rear tyres are slightly worn and there is the aforementioned damage around the rear body mounting hole, plus a lot of scuffing on the underside), a lot of the parts barely seem worn at all (the body is otherwise in remarkably good condition, as is the spur gear, while the front tyres look like they're straight out of the packet). Given the state of the steering set-up, it can't have been used in that condition as it won't turn corners like that, so I am guessing it was rebuilt from a used chassis into a rarely used or unused ornament, later sold to make space.

These are going straight in the pit box, though.

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Do the UJ driveshafts fit? Yes they do! Well, sort of.

This is one of the problems with having been away from the hobby for nearly 25 years. Things you would have remembered to check back then you forget to check now. While the UJ driveshafts fit, after putting the wheels back on I realise that the threaded stub axles may not be long enough to hold the wheelnuts on.

I gather that RC wheelnuts have a plastic section at the 'outer' edge of the nut, with the idea being that this section grips the thread and stops the nuts from coming loose and your wheels from falling off. However, this means that the amount of thread available has to be at least the depth of the wheelnut, as otherwise the plastic section will not have anything to hold on to and you will effectively just be trying to hold your wheel on with a conventional steel nut. This will rapidly come unscrewed from your threaded stub axle shortly after you pull away, with obviously disastrous consequences and the loss of your nuts. The threaded section here does not quite protrude from the centre on the nut (as they did with the previous arrangement) so I may have to remove the UJ shafts again and replace them with the conventional shafts.

One of the UJ shafts is also slightly bent, which is probably from a front-on impact when mounted in the front of a Mid, which broke a plastic lower front suspension arm and caused the shaft to take some of the impact. This used to happen with alarming regularity with the tiny, standard Mid front bumper, as the front arms were exposed and very vulnerable. It is also why you see Mids in period pictures wearing such a wide variety of huge and ugly front bumpers. None of them worked, as the front bumper mountings were hopelessly inadequate and the things always used to snap off. This is the reason why the front bumper mount is one of the few things about the Mid I'd change: it's rubbish.

Sorry, that was a bit of a rant. Back to the scheduled programming.

The bend isn't enough to not use the the UJ shafts – they still work well enough for our purposes here – but the wheelnut issue might be. We will see.

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With the driveshafts being so easy to change, we can afford to leave the questionable UJ shafts in situ and come back to them later if required. Next up: removing the motor.

It is at this point I must confess that my normal healthy respect for Kyosho's design team – already slightly dented by the Raider's woeful steering arrangement – takes another battering.

Anyone who read the earlier parts of this thread may remember that my earlier efforts to get the motor out were stymied by not having the right screwdriver handy. A pretty dumb reason to have to stop a strip-down, but hopefully understandable given the amount of time since I last did this and the amount that my toolbox has been plundered in the intervening years.

Now, though, I am faced with a motor which simply cannot be removed. The Raider's motor mounting is a complicated arrangement which involves no fewer than five pieces: pinion, inner brace, gearbox casing, mounting plate, motor. Getting all of these lined up would be hard enough in itself, but that is just the way of things. The tough bit apparently comes when the car, like this one, has been fitted with a 15t pinion. This makes the pinion bigger than the bearing housing on the motor, which in turn is the reason for the size of the hole in the inner brace which the motor fits into. The upshot of this is that even when you have removed the mounting screws the motor will not come out, as the pinion won't fit through the hole in the inner brace and the inner brace won't fit through the hole in the side of the gearbox casing.

Earlier on I spent some time looking at this and cursing Kyosho and its design team and wishing that wherever they were they were unable to get dressed, as the legs of their trousers had magically shrunk so that their feet would no longer fit through them. At this point my daughter woke up and frustratingly put Raider shenanigans on hold again. Later, I rechecked the instruction manual and saw that the obvious answer was to remove the top of the gearbox and then remove the pinion. This is virtually impossible via the access panel on the other, non-motor side of the gearbox, as you obviously can't see the allen screw or sufficiently move the allen key.

This is another thing I would have spotted straight away if I'd been doing this at 17 rather than 42. As a result, this rebuild may end up going down in history as the dumbest series of mistakes and oversights ever posted here.

Oh well. Maybe the servo will be easier.

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I've got three models with this gearbox, RS500 & two Rockys. Seems a real pain at first but then you get used to it it pretty easy. 

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When you put it back together, I've found that it helps to flip the gearbox horizontal so the motor points up.  Doing this helps negate the effects of gravity on the two aluminum plates that go on either side of the gearbox.  Otherwise it's very difficult to keep the holes aligned enough to get a screw down through all of the pieces.

Use a hex driver or similar long thin tool that can poke down through the gearbox side access hole and through the inner motor mount plate, gearbox, outer motor mount plate and into one of the motor screw holes for alignment.  I use a 1.5mm hex driver for this.  I do this for one hole and just leave the hex driver inserted into that hole while I align the second hole with another hex driver.  Once that is done, I put a motor screw on a philips head screwdriver (letting magnetism or whatever putty/glue you want to use keep the screw on the head of the screwdriver) and insert it down into the hole and screw it in most of the way.  Then I pull out the hex driver while keeping all the holes aligned and screw in the second screw.

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When I started this thread, I called "Quick Kyosho Raider Rebuild" because I thought it would only take a few hours. Replace the driveshafts, the motor and the servo saver, change the back wheels, sort the electronics and Robert is your mother's brother.

However, I'd forgotten how frustrating these things can be. Especially cars you don't know your way around. You may recall that in the last instalment I got stuck because I couldn't find a way of accessing the pinion so I could get the motor out. The obvious answer is to take the top cover of the gearbox off, so I have just done this, to reveal a fairly healthy looking geartrain. No excessive wear, a sensible amount of grease and no nicks or missing teeth. Lovely. So all we need to do is get the pinion off.

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Ah. The pinion will not come off. I have the correct allen key (two of them, in fact), but they just click round in the grub screw without loosening it. Either the grub screw's hex-shaped hole is internally worn or my allen keys are. Or both. That is not ideal.

Does anyone have any tips for getting a worn but very tight grub screw out?

Perhaps this is why the Raider came with such a lairy motor? The previous owner installed the Dyna Run and then couldn't get the thing out.

*Sigh.*

 

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Once the Dyna Run is finally out, I have this waiting to go in. A pretty much generic 21T (presumably) machine-wound modified, which should be more than enough for a chap who hasn't driven an RC for over 20 years and his 2-year-old daughter who hasn't ever driven one. Alternatively, we may keep the Tamiya motor in there forever. We may have to.

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You could drill out the grub screw, but that could be very tricky with the motor in that position.

The other option is to carefully lever or pull the pinion off. Once off there will be no tension on the grub screw & it should unscrew alowing you to fit a new one.

I've had to do this before myself. If you are carefull you wont damage anything.

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I have ordered some new titanium-plated hex drivers to see if that helps. If not, the next obvious route is to deploy explosives. I also almost bought an RC10 B4 off eBay today, so frustrated am I with this nonsense.

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What a pain this thing is.  I've done a few Raiders in the past couple of years but did not run into this kind of trouble.

Rounding grub hexes are the worst.  I would take all of the rest of the gears out of the gearbox and use a heat gun on low-medium heat (300C or so) and aim it at the pinion.  The gearbox plastic is pretty tough and can handle a fair amount of heat, but take it easy.  Start far away and gradually move the heat gun tip closer to the pinion, checking for plastic deformation along the way.  Every so often try the hex key on the grub screw.  The heat might be enough to help loosen the thread lock on the grub screw and the differing coefficient of expansion of the grub screw steel vs brass pinion might help as well.

For grub hexes that are almost worn out, I try to hold the hex key at an angle (that is, not perpendicular like normal) while twisting in an attempt to grab the sides of the grub screw hexes in order to prevent further rounding of the grub hex or key.  Sometimes that can work, but if it's really tight or too rounded out it won't.  So, failing that, I'm not sure what I would try next.  Maybe see if I can get a dremel in there with a cutting disc and cut a channel in the grub screw.  Just enough to make a slot that a flat-head screwdriver can grab on to. Of course the cutoff wheel disc is usually almost the same width as the grub screw so that may not work.

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Having taken a Dremel to a grub screw once or twice, and honestly this just came to me... A soldering iron to the pinion may work, I haven't tried it but I think it would work at least as well as a heat gun. Perhaps wrap a small damp towel around the motor shaft for cooling to keep from cooking anything.

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5 hours ago, Pablo68 said:

Wow, it's all happening with this build.

The problem was that for a long time, nothing was happening with this build. I just got back from a fortnight's holiday, though, and waiting for me when I returned were the hex drivers I ordered from ebay and a brand new TBG repro Raider shell. So hopefully things will be moving on apace over the next week.

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On 10/5/2018 at 5:39 AM, geniusanthony said:

Having taken a Dremel to a grub screw once or twice, and honestly this just came to me... A soldering iron to the pinion may work, I haven't tried it but I think it would work at least as well as a heat gun. Perhaps wrap a small damp towel around the motor shaft for cooling to keep from cooking anything.

I had thought of something similar, but due to the design of the Raider, not being able to remove the pinion means that I also can't remove the motor from the gearbox and I am a bit scared of accidentally melting the casing with the soldering iron if I try this. Plus adding a damp towel would be virtually impossible in the space available.

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On 9/16/2018 at 9:28 AM, Ann3x said:

Or dremel through the motor shaft (as a last resort)

Ooh, don't tempt me...

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7 hours ago, Yalson said:

Ooh, don't tempt me...

Better to lose a motor than a car. 

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On 10/14/2018 at 10:50 PM, Ann3x said:

Better to lose a motor than a car. 

Not this one. Given how much I paid for the car, the motor may actually be worth more.

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Right.

Anyone who has been following this thread will know that this car, appealing as it looked on eBay and to the layman (me) when it arrived, has thwarted me ever since I first tried to get it running. Leaving aside the bizarre steering issues it suffers from, which I will tackle at a later date, the fact that I can't get the pinion off of the motor – consequently meaning that I can't get the motor out of the car – is the biggest issue immediately facing the rebuild. The grub screw in the pinion was either too worn to accept the allen keys I had, or the allen keys were. Or possibly both. Anyway, it wasn't coming out on its own, so measures had to be taken.

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A set of titanium hex drivers from eBay. Less than a tenner, but seemingly very nice. Pleasingly heavy to hold and the hexes are sharp as tacks. Lovely.

So I take up the 1.5mm driver, slot it into the grub screw and try and turn.

Nothing. It is as tight as... well, a very tight thing. Won't move. So I turn a little harder and *pop*. "That sounds encouraging," I think. But no. The sound was not the driver forcing the grub screw loose, it was the hard, sharp edges of the driver simply wiping out what remained of the hex shape. It is now almost completely round and the driver can now get no purchase on it at all.

This is less than ideal.

To show exactly how sub-optimal this is, here is a picture of the space there is a available to try other methods of extracting the pinion and motor.

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Levering the pinion off with a pair of pliers is not possible, as there isn't enough room to force the pinion off without potentially damaging the spur gear. The tight confines of the gearbox also make me wary of @geniusanthony's otherwise excellent plan of heating the pinion with a soldering iron.

I fear we may end up either drilling the grub screw out or taking the car apart with the motor still in situ.

Or I may buy another car and bury this one in the garden.

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