RadioShack Hot Machine conversion

[Nikko85]

Another build using a vintage toy grade car and upgrading it to make it much more user friendly and faster.

This build uses a RadioShack Hot Machine as the base. The Hot Machine was made for RS in the 90s and is a great example of just how good quality these toys used to be. The truck is four wheel drive with differential on front and rear wheels, two speed gearbox, decent suspension and soft rubber tyres. This car has clearly taken a lot from the Quick Drive MT series with the chassis being almost identical, and the bodies are swappable with no modification needed. The tires are also a perfect match too, which gives me many more options if I need to upgrade.

The car cost me £11.50 posted, and there are a fair few about, so it should not be hard to find spares if something breaks (....in fact I've got another on the way..)

As always it's not all good news - the electronics are not great, the steering slow and the 360 motor underpowered and there doesn't seem to be any options for bearings. Interestingly when I gave the RadioShack Off Roader a new ESC it went quite quickly (despite the 280 motor) so I'm not sure what's going on here, as a quick trial with a proper Esc was still pretty slow - the 360 motor might just be a really bad one perhaps? Or the drivetrain has a massive amount of friction, but despite the car having no bearings the wheels seem to spin ok when the motor is taken out, so we shall see.

the plan is:

• replace the 360 Motor with a more powerful 380 or 390 motor. I don't want to go brushless, as this doesn't have bearings, and I don't want to destroy the gearbox either
• add a proper steering servo
• add a new Esc, radio gear etc.
• file down the battery bay to take a 7.2v or 9.6v stick
• remove the monstrous body shell and replace with the 1/15 Clodbuster ish style body I've got
• remove the peeling chrome on the wheels and paint white
• do something with that massive front bumper 

Hopefully by the end I'll have a car that looks like a 1/15 Clod, but is 4x4 and fast enough to be a little bit exciting (20-25 km/h would be perfect). 

Anyway, here is the original. You can see the body is oversized and really doesn't look that great, but I'm hoping I'm going to get something that looks much more scale. I like the suitable for "smooth off-road" line on the box, it hardly inspires confidence but I think with a little more power this will be quite capable of getting over some decent lumps, the low gear is very low indeed, the suspension is ok too (for what it is..) and it takes full sized MP tires.

I'll begin by stripping it all down, and seeing how to install a steering servo, as this is pretty critical and might not be easy. The front end of this car is different to the QD as it's 4WD, so hopefully there will be a good solution. The rear is just installing a new motor, a piece of cake I hope.

I know these aren't for everyone, but hopefully this may inspire someone, and there are lots around on Ebay.

 

 

 

[Nikko85]

Well, I managed to get a huge chunk of this done today.

First thing I looked at was the steering. The original used a 5 wire servo with non proportional steering. This was  slow, and really needed sorting out if this car was going to be good for anything but sitting on a shelf. The picture below is the original set up, you can see that quite a bit of hot glue was used on the original to fix wires in place.

The original servo was connected to the an L shaped cover that sits over the gears. I removed this cover to have a look inside. 

See the white box inside the hole? This is what the servo has to connect to. I put together a servo horn with a little screw as a nub that would do the job. I think the photo below is an early prototype.  With some super sticky double sided pads and electrical tape I attached this to the vertical part of the L shaped cover. Thankfully the fit was almost perfect with the modern servo just fitting in where the old one used to sit with an almost identical action.

You can see a sticky pad is sandwiched between the servo and the cover. The whole thing is tightly bound in electrical tape. I flipped it over, slotted it in and screwed it all together, and job done. I've seen a few people say the steering is really tricky on these cars, but I think they removed the entire assembly and tried something more radical.

I'm amazed at how solid it feels. I really didn't want to glue anything, but this way I've managed to get a modern servo to fit with no dremel action, and I can replace the servo easily enough. The range of steering is really good, I used a decent etronix servo to give it some punch. There is a bit of play in the steering, but I can live with that, this car isn't meant to track a perfect racing line or anything.

With that done I had a look at the motor. The only tricky bit was removing the original pinion but in the end it came off, the 360 motor was removed and a Helion 390 motor added. The pinion is just a push fit so I'll need to add some loctite soon. 

The motor just about fits, it's about 2 mm from the shocks. Connected to a HW 1060 the is a huge difference in speed and acceleration compared to the 360. This thing will wheelie on on a wooden floor (whilst in high gear) and was happy ploughing through the grass on my lawn that's not been mowed this last summer. Amazing difference in performance. Not been outside to test speed yet, but the punch is fantastic with a low gearing and 4WD. Too fast to drive indoors for sure.

Rather than use 8 x AA batteries I made space for a 9.6v pack, which fitted with very little drama at all.

For the main mechanism of the car that was about it.

Next was the bodywork. I wanted white wheels, so out came the spray paint. I'm not very good at spray painting, but I'm getting better, and it was simple enough, I just always rush and never wait for coats to dry.

The body of this car was my QD clone which stopped working as the motor kept cooking due to high gearing. I redid the chrome bits, as these were really cheap looking. I went for a gloss black base coat with the "chrome" over the top. It's not really chrome, but it looks like a nice aluminium or stainless steel vibe.

And here it is: 

I also chopped down the massive front bumper and re-attached.

And it's pretty much done. I need to

• finish the black and yellow pinstriping (for this I need some more electrical tape)
• see if I can add bearings (at least the the main axles) to keep the grit out the gearboxes
• add some lights
• add a lower bumper
• add my cat as a driver

Overall very happy so far. It looks like a mini clodbuster, and being 4x4 has a little more in common with a real clod than the QD series version. It's really pretty punchy, much more so than I was expecting; that 390 motor has really given it some zip.

Best thing is the car cost £11 posted, and I've got an all black version in the pipeline. This will use the strange wheels you can see in the first picture.

Any questions, do shout and hopefully this can inspire someone to take the plunge and try some of these toy grade classics.

[Nikko85]

All done alongside the proper QD. Nothing on the 'Clod' is made by Tamiya, but matches very well. Tyres are almost identical as you can see! Other bits are just very similar in design. Maybe slightly thinner plastic,  but seems the same quality.

Will be fun to compare them driving, the pumpkin is 2WD at 1.6 kg with a 2030 brushless, the Clod is 2.1 kg with a low turn 390 and 4WD. Heavier but does seem more powerful, just like a mini Clod should be! Both are powered by a 9.6v pack, very 90s toy grade. In fact these feel like the toys I wish they had made when I was 13.

I'd love to compare to the real Clod too, but I think if they collided mine would turn to dust. 

[Nikko85]

Inaurgural run this morning driving in the mostly empty park.

First impressions are good, although perhaps a little lacking in top end speed. On concrete it did pick up the pace, but I think even the high gear is too low for any super speed, perhaps 20 km/h or so. On grass and bumps it was great however, even in high gear it just simply ploughed through fields even the longest thickest grass. Great for a trail, wooded areas, dirt and foliage.

Unlike the QD Pumpkin the car won't grip roll, perhaps due to the wider stance, but when driving the grip is great and it's surprisingly able to stay in a straight line, even on very bumpy ground, which may be the 4WD in play.

Next stop, brushless perhaps? I know I said I didn't want it too fast, but a little extra boost would be good. Might just need a fresh battery or the most insane 390 I can find. 

[Nikko85]

For the first time in ages I had my car with me at the same time the BMX track was free.

So much fun! I really need to get a video up, but it really does seem to drive much like a mini clod. Motor on axle, 4WD, low gears, bouncy suspension and ploughs through anything at all. Even on high gear it was able to easily climb the biggest hills of the bmx track - only got a few inches of air, but enough to make it fun. The low gearing limits the speed a fair bit, but it's great up hills, in long grass, on gravel, dirt, grass, and on tarmac gets up to enough speed, but won't roll.

 

[nowinaminute]

You always seem to work on the same stuff as me lol. I have a brushless hot machine!

The gearing is indeed very low! They are nicely built though. I think this is also the same company that made the Tamiya QD stuff and also the Radio Shack 4x4 summers etc. The clutch inside is a great touch!

I haven't taken mine out for ages. On the first run, a nut fell off the steering linkage and as usual, I put it aside and moved onto something else lol. I should really get it back out again.

Great build thread!

[Dakratfink]

This thread is inspiring me to get an ESC and receiver for my 1/5 Marui Motorcycle restoration .

( separate thread in the Marui section ) 

[Nikko85]

18 hours ago, nowinaminute said:

You always seem to work on the same stuff as me lol. I have a brushless hot machine!

The gearing is indeed very low! They are nicely built though. I think this is also the same company that made the Tamiya QD stuff and also the Radio Shack 4x4 summers etc. The clutch inside is a great touch!

I haven't taken mine out for ages. On the first run, a nut fell off the steering linkage and as usual, I put it aside and moved onto something else lol. I should really get it back out again.

Great build thread!

haa haa, yes, - and on that note I've just finished an iconic Yellow Tandy Off Roader - which I'll add to the other thread. I've got a real thing for these 1/14 or so scale monster trucks. Despite the user name I find that it's the Radio Shack and Tandy trucks that seems to offer the best value - the Nikko stuff is much more £££ and often harder to convert. The best thing is that the Hot machines, Tamiya QD and Radio Shack/Tandy/Taiyo Off Roaders all have interchangeable bodies, and a few other bits - so you can mix and match spares. The Hot Machines would also be a good way to get cheap spares tires for an LB or MP - an exact fit.

Could I ask if you were able to fit any bearings to the hot machine? I've just picked up another for £5 - I may go brushless on this one, as spares are so cheap even if I kill the gearbox it doesn't really matter too much.

The gearing is very low. My thought is that it's quite a heavy truck and the original motor is really weedy, so they needed low gearing to ensure that they moved at all. Now the power is so much greater even on high gear it'll plough through heavy grass and up hills, but could do with a speed boost. Love the way it moves however, and the fact that you can hit grass higher than the truck and it doesn't really slow down is great - my 1/10 540 buggy can't do half what this can (although much faster....).

 

 

[nowinaminute]

3 hours ago, Nikko85 said:

haa haa, yes, - and on that I've just finished an iconic Yellow Tandy Off Roader

I forgot to ask, did you happen to keep the stock electronics? I'm on the lookout for a stock steering servo!
 

3 hours ago, Nikko85 said:

Could I ask if you were able to fit any bearings to the hot machine?

It looked feasible but I never got round to measuring them to see if they match up to standardised bearings.

 

3 hours ago, Nikko85 said:

The gearing is very low! My thought is that it's quite a heavy truck and the original motor is really weedy, so they needed low gearing to ensure that they moved at all. Now the power is so much greater even on high gear it'll plough through heavy grass and up hills, but could do with a speed boost.

There are some versions with taller gearing but I don't think they sold them in the UK so I've never been able to get my hands on one. I can't remember the names off the top of my head but I think there's two gears that are different and it makes it significantly faster.

This is the only video I ever got of mine. Not very good footage at all and at the end, when I had just put it into the high gear, the nut holding one of the steering links on fell off! Easy fix but it has been sat on a shelf ever since!
 

 

[Nikko85]

Well the inevitable happened, I put the small brushless EZ run combo in it. Amazingly the 2030 EZ run gives it a real speed boost compared to the 390 motor, despite being 1/4 the size. There is however more cogging and less torque, and with a higher top speed comes less ability to just plow through grass etc. It's also much nosier, which is probably the higher rpms. I hope the gear box survives.

With a little play I've lowered the punch and degree of the motor, which has helped. Still not got that smooth low end of the 390, but it's faster in a straight line for sure. I love how the 390 version doesn't get slowed down by really thick grass etc, where as the Ez run is much more surface dependent but top speed is much nicer.

These 2030 motors are incredible for the size, it's a 1/4 the volume of the 390, yet, so speedy.

 

 

 

[Nikko85]

A few more edits and photos.

Really enjoying this truck. I spent a little bit more time on appearance and electronics last night

I was able to give the grill a better look by painting the base black and then the grill itself in in chrome. I did this by masking off the grill and painting it all black, and then using the chrome paint looking almost straight down from the top. The recessed parts of the grill stayed black, whilst the chrome paint hit the raised bits, perfect! 

I also used a sharpie to give the lights some colour. I coloured both sides of the clear plastic, and it looks much better now.

I was also a little fed up of having to take out the 8 AA batteries each time to charge the car, so I've placed the Tamiya plug running out of the car and back in, although it doesn't quite look at good it means it's much easier to charge, and I can leave the batteries in place. The picture below shows the cable a little tucked out, it does sit pretty much flush. I may paint black.

I then took it out for a run the 2030 motor is doing really well. It's the same combo I have in the 1/14 Midnight Pumpkin and works well here. It doesn't have as much initial push off the line as the 390 motor, but top speed is much better. Although it doesn't have the same torque it seems to run about as quick as the Tamiya Heavy Dump - nothing amazing, but for a 2030 motor on a toy grade chassis running on 8 x AA batteries - that's great. The batteries are placed right between both wheels so it's surprisingly well balanced. 

The suspension is bumpy with friction shocks, but it adds to the look I think. It does well in grass and over rough terrain, as the wheels are 115 mm.

Interestingly I saw the real QD Clod go for about £90 on Ebay last week - so I'd say this is a good value option, and with the little brushless motor much faster and it's 4WD, just like the real thing.

 

[ivxcvi]

So glad I found this. I'm in the middle of updating my own RS Hot Machine from my childhood (different version though, but not that much different).

Any updates on this? I'm planning to spend my afternoon taking measurements & putting together a shopping list for a servo & motor. My plan is to put an F405-WSE in it as a controller unit.

[Nikko85]

Not really.

 If you want brushless go for a Hobby wing EZrun 18T 2030 motor and ESC combo. Alternatively a 390 motor will also fit nicely, I found some FTX ones on ebay. Despite being half the size the EZrun will give more speed, but at the expense of smoothness. 

Servo was a standard size - although a servo saver will be useful.

I've no idea what a F405-WSE would do, I just used a cheap £20 controller and receiver. I stuck with 8 x AA batteries, although I soldered the two battery terminus to a Tamiya plug, which went outside the chassis, and then back into the chassis into the ESC. That way I could charge using an NiMH charger without having to take out the batteries or undo the body.

Another option for power is a 7.4V Li-Ion battery. They seem to give about as much kick as the 8 x AA batteries, and are much lighter. 

 

 

[ivxcvi]

Thanks so much for reply & suggestions.

The F405-WSE would be an attempt at future-proofing it somewhat. I'd have more software control over more servos & lights than an AIO receiver module. It'll be a true project RC car. I plan on adding more to it as time goes on, but I want to start by just getting it running with modern motors & a LiPo (or Li-Ion pack) first.

Will post to share results in a new thread once I see working results. I expect it to be some time yet, but I want to at least get it reassembled as its laying in pieces at the moment.

Thanks again. Will return with more as time allows.

[Nikko85]

A little update. I really enjoyed this truck, so I've decided to build another.

This one is going to use the classic Tandy/Radioshack 4x4 body, and given some bigfoot decals. It's not quite the same body as the bigfoot, but close enough. The proportions look pretty good. I may look out for a cheap Hot Machine II for spares. These also have different wheels, allowing the use of the Tamiya LB/Pumpkin wheel.

It's a little wide and tall - but then it's all full 80s monster truck ridiculousness so that's fine.

 

[JimBear]

Just loved the short video you did earlier, with the couple being "beamed in" on the walking path to the right.

Keep'em coming!

[Nikko85]

1 hour ago, JimBear said:

Just loved the short video you did earlier, with the couple being "beamed in" on the walking path to the right.

Keep'em coming!

I'd love to say that was me, but I have no idea what you are talking about! Wrong post perhaps...

[JimBear]

1 hour ago, Nikko85 said:

I'd love to say that was me, but I have no idea what you are talking about! Wrong post perhaps...

In the video you made (shown above), about 15 seconds in - probably because the video is edited -  a walking couple (in blue and red clothes) just "magically" appears in the extreme right of the frame, as if they were "beamed in" (a la Star Trek).

Never mind - I am just enjoying your work, that's all.

[Nikko85]

I added body posts to the front

In stock form the rear is attached with a M4 bolt. The QD trucks use a similar arrangement at the rear, with a slot in the front of the chassis to take a tab on the body. For the Quick Drives this is fine, and it's nice to have no visible posts, but I often find myself looking for an allen key just to take the body off.

As this truck now has posts at the front, I thought I'd make a post at the rear. I 3D printed a body post that can screw into the M4 nut in the chassis.

Hopefully this should hold up ok. It will be printed at 90 degrees to keep the strength in the print. I can't image the thread holding up to repeated use, but it should be enough to hold fast once in. Otherwise I could drill out the M4 bolt imbedded in the chassis and then glue in a body post in the 5.5 mm hole, but that's a less elegant solution.

[Nikko85]

Got a good chunk of this done last night. I 3D printed the rear mount and screwed into the rear. I took off the spokes and painted the wheels white.

I then stripped the body and repainted blue. I wasnt going to repaint but it was really sun faded, so parts under the stickers were a totally different colour. It's really getting there. I now need to source 1/16 bigfoot decals somehow; there seem to be ones for the playskool bigfoot which could work?

Looking proper 80s ridiculous now. Its wider than it should be but that's not a big issue, means much fewer roll overs.

[Mouc-RC]

Excellent! Those grill & air filters really look the part

If you have access to a lathe, you can easily remove the spikes from those chevron tires, with just... a file. Did this on some Stadium Blitzer fronts, only to have the ribs on them.

I guess you can also cut them with some sharp knife, and then sandpaper (more work, though)

[Nikko85]

Another repaint job after the first paint job failed (wrong paint, bad adhesion)

I also stuck the side chrome one. I still need to trim body posts and do a little work, but it's getting there.

I've also been working up some stickers, these will be printed on water proof sticky vinyl. Rather than print on clear I'm going to colour match the body as best as I can, and then cut out a square and stick on. This is a Radioshack truck, so I don't mind the idea of a certain degree of "toy-ness" about it - it's not a replica of Bigfoot, it's a replica of an 80s toy of Bigfoot. As I'm colour matching I'm trying a few different print outs of colours so I can match the best. The real pictures are quite high resolution.

[Nikko85]

Today I printed stickers. First two laser jet printers totally failed to print but third office printer lucky gave me the results I need.

The resolution is fine for me. Colour match is pretty darn good. Not perfect but close enough. For some reason the printer added slightly different colour boxes around each icon that didn't exist in the file (either straight from ppt or exported to PDF) so not quite sure what is happening there. Very strange.

This is almost done now, just really need to sort wiring and add body mounts.

It's not a super close replica, but for a Radio Shack it's very good. I am imagining this as the best version of the toy grade 80s and 90s monster trucks possible.

It may mainly go on a shelf, but with the little brushless motor it will rip along, so it would shame not to drive a little..😉

 

[Nikko85]

So this is all wrapped up! I still need to drive it, but I've had one of these before so zero issues. I may look out for a second RS to keep as spares. These trucks seem to be really plentiful on ebay, often hardly used. The original motor is quite underpowered, so most have very little damage, and available for £20 or so.

At the moment it's got a little brushless motor in it, I've had good luck with 390s too, less speed but a little more grunt.

Photographed with my other 1/16 truck - my little QD SCT (1/16 slash body!)

 

[Nikko85]

I've just spent £23 on another one of these for spares. I picked up the Hot Machine II. These have the benefit of taking 115 x 71 mm tamiya tires. The wheels are also wider and have less offset, so they tuck under the body more, meaning it's got a more of a classic monster truck look and less a truggy look. It'll also mean a spare pair of axles and chassis, which can only help.