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Blakbird's 57409 Mini Lunchbox Build 3 years 11 months ago #59063

There have been a glut of "comical" versions of old buggies lately, but they are not particularly interesting to me. This Mini Lunchbox, on the other hand, is adorable. The original 58063 Lunchbox was listed as 1/12 scale and this is 1/24. It may be even smaller than that; the ratio of the body size to chassis is different than the original. Like the original, this is a wheelie chassis. Unlike the original, this has a polycarbonate body, is four wheel drive, and has optional four wheel steering. Four wheel drive might seem somewhat pointless on a vehicle which is likely to have the front wheels off the ground, but it possible to steer using the rear wheels.

This little guy is a lot more complex than you might think and was a blast to build on the brand new SW-01 chassis. It comes with a 370 motor, but unlike most Tamiya kits does not include an ESC and does not use a standard battery. I used the same mini Hobbywing system that I put in my Dancing Rider which worked perfectly. It is fun to drive on pavement, hard wood, or carpet and does all the stunts you could want including forward rolls. The suspension and steering are highly unusual and are explained in much more detail below.

Considering the tiny size of the Lunchbox Mini, the box is pretty big. You can see what a small portion of the space is consumed by the body. There is ample empty space within the volume of the box.
The parts cover only a small portion of my build table, and there isn't much hardware either. Still, the build ended up being more complex than I expected.
The chassis parts are molded in very light gray while the gears are black. The kit did not come with ball bearings, so the rubber sealed bearings you see were supplied separately by me. In the first step, a pair of spur gears are installed within the chassis housing and enclosed.
The next set of gears installs from the outside of the chassis side and is then hidden by a cover as shown. The larger end of the gears are quite close together. The motor spur gear will span them and drive both at the same time.
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Blakbird's 57409 Mini Lunchbox Build 3 years 11 months ago #59064

Here is the 370 sized brushed motor installed in its mount. The 16 tooth pinion gear is plastic and just presses onto the motor output shaft. An 18 tooth gear can also be used for more top speed and less torque, but this would come at the expense of wheelie performance. On the right you can see the planetary style gear differentials which come from the T3-01 and are identical front and rear.
The outdrive axles have a dogbone at one end and a universal joint in the middle which must be assembled manually. Unlike the T3-01, the spline alone is not expected to carry the torque to the dogbone, there is also a set screw inserted. On the right you can see the first set of axles installed in the front uprights. The cotter pins are only there temporarily to keep things together until the wheels are installed.
The steering system on this vehicle is not like anything I've seen before. The springs on the upper kingpins serve as the only suspension. The bar which spans them pivots on the chassis tipping the entire front axle back and forth. The steering therefore results in body lean more like a motorcycle than a car. The differential installs from the end of the chassis and is enclosed by a cover as shown.
The front bumper and lower arms complete the front suspension, then the rear is built in a very similar way. The only difference is that the upper lever arm does not have a vertical slotted drive crank like the front. Instead of a bumper, the rear of the chassis gets a wheelie bar.
The following user(s) Liked this: stingray-63

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Blakbird's 57409 Mini Lunchbox Build 3 years 11 months ago #59065

The steering just keeps getting stranger. The crank mechanism shown serves both to turn the steering knuckles and to lean the suspension at the same time. From bottom to top, the lower bronze ball joints drive the steering arms, the screws above them support the lower lateral link, the screws above those are the fixed structural pivots, and the screws at the top support the upper lateral link. One of the structural pivots is driven by a crank which will later attach to the steering servo.
This view from above is intended to help with understanding of the steering system, but probably doesn't. You really need to see it in motion for it to make sense, and even then it is strange. Note that the rear axle uses links which fix to the chassis so that the rear doesn't steer. This can be changed with upgrade parts.
The electronics are all installed on their own upper bracket assembly. Shown on the left is the installation of the steering servo. The slot behind it is intended for a 4-AA battery box which only comes with the Japanese version of the kit or a Lithium-Iron battery which is likewise Japanese only. I'll be using a small 2s LiPo. I stuck a small ESC to the top of the servo and the receiver atop the battery box.
Now the electronics assembly can be bolted to the top of the chassis. To mechanically connect it to the chassis only a small steering tie rod is needed. To electrically connect it, you just need to plug in the motor wires. Now the body can be started. The yellow body comes painted but mostly uncut. Only the wheel arches have been pre-trimmed. The picture on the right shows the result after I've completely cut out the body. Note that there are no clear windows.
The stickers must be painstakingly cut out and applied. In addition to being small, they are also quite intricate. For example, the stickers which must bend around the front bumper and headlights have several triangular notches which allow them to cover properly as shown. The completed body is shown on the right. The windows are just stickers. The plastic parts on the lower sides serve to simulate the side pipes of the bigger Lunchbox as well as support the body on the chassis.

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Blakbird's 57409 Mini Lunchbox Build 3 years 11 months ago #59066

Out of the box only the front wheels of the model steer. These "arm connectors" effectively make the model have four wheel steering, but interestingly don't actually say that on the packaging. Only the lean of the front arms is transferred to the back, not the steering angle. The steering angle is a secondary effect of the lean.
It's not exactly an upgrade, but the kit comes with a thick paper board which can be cut and folded into a wedge. Installed in the roof, this wedge allows complete forward rollovers.
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Blakbird's 57409 Mini Lunchbox Build 3 years 11 months ago #59067

There's nothing super exciting about the appearance of the Mini Lunchbox, but it does a reasonable job of approximating the real thing in a cartoonish sort of way.






Here's a comparison to his big brother.
The following user(s) Liked this: Jonny Retro, stingray-63

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Blakbird's 57409 Mini Lunchbox Build 3 years 11 months ago #59069

I've been curious about these little things - thanks to your excellent write up I can see that they're really not for me ... unless they make a Wild Willy and/or Wheeler with a proper body, then I might have to have them for completeness.

:)

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Blakbird's 57409 Mini Lunchbox Build 3 years 11 months ago #59075

I was curious to. And now, I want one

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Blakbird's 57409 Mini Lunchbox Build 3 years 11 months ago #59079

It doesn't scratch the same itch as a classic Tamiya set, but it puts a smile on your face like all Tamiya's. Fun to drive around inside when trapped by bad weather or global pandemics.

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Blakbird's 57409 Mini Lunchbox Build 3 years 11 months ago #59080

Yep and very compact to have fun at work to. :P

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Blakbird's 57409 Mini Lunchbox Build 3 years 11 months ago #59081

I can't really say I want one, even as a hardcore Lunchbox fan.

This is the same class as Dancing Rider for me, and are too toy for my liking.
If this thing had a bit smaller and wider tires to mimic the orginal Lunchbox, maybe I would be more intrested.
Seen videos of it in action and there seems not a great deal of space to fit anything but the orginal wheel combo.
I take these are M size wheels, or are they smaller?

Anyway, really good writeup as usual :y:

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