The eAssault – Electric Monoshock Assault

The eAssault project started when I bought an old Kyosho Advance chassis to get the shocks to use for my Kyosho Turbo Scorpion build. At first I didn’t have any plans for the rest of the car, as it was missing a lot of parts, including the engine, and I never cared for nitro/gas powered buggies. Too much noise, and too much mess with the fuel. But when I got it, I found everything to be in much better condition than I expected, and instead of breaking the car for parts, I decided to try converting the buggy to electric. After all, it’s in the Scorpion series family that I love so much, and it share about 90% of the parts with it’s electric cousins. As I also had one of the monoshock units left from my “Mohawk” build, I figured it would be fun and unique to make this one a “mono” as well.

Chassis with the electric motor fitted.

For my “special” builds I have always taken very much care of colours. Limiting the colour scheme to a few base colours, makes the buggies look clean and special. Being very satisfied with the clean red/white/black scheme for both the “Mohawk” and the “Akira tribute”, I decided to stay on the same path, adapting the original Assault colours black/yellow to black/yellow/gold as base colours for the eAsault. The body will be painted box art(ish), and the red shocks (that were already sitting on my Turbo Scorpion) had to make way for the beautiful Kyosho gold shocks (from the Turbo Optima etc). Some might think that those gold shocks are incorrect for the Scorpion series/Assault era, and so did I. But in the Japanese Kyosho catalog from 1987, both the Turbo Optima (with the gold shocks) and the Assault are listed as present products, so the gold shocks would be OK for this build, although within a very small margin 😉

The original Assault with the “characteristic” rear hanging engine.

I’m not actually a big fan of the Assault looks. One of the things that, in my opinion, makes it look odd, is the engine sticking so far out at the back. But that’s also the main feature that makes it different from the electric Scorpion series buggies like the Scorpion, the Beetle, the Tomahawk, and the Turbo Scorpion. It’s definitely the one thing that makes it unique. The most sensible (and absolutely the easiest) thing to do when converting it to electric, would be to just get rid of the “bolt on” extra part of the gear box, that converts the input from the side to the back, and go for the standard Scorpion type setup instead, with the side mounted motor plate and the sideways mounted electric motor. But what’s the fun in that? That would just be a Scorpion with an Assault body, and that was not what I wanted. For it to still be an Assault, the motor has to be mounted lenghtwise, sticking out of the back. To be able to do this, without doing any damage to the original parts, took some thinking and quite a bit of trial and error. My first thought was to make a motor plate with a 90 degree angle, and bolt it on to the same place as the standard Scorpion motor plate. That could still be a nice solution. But not having the machining tools to make such a plate, I would have to rely on others making the part. But then I was browsing eBay (I do that waaay to much….) and found this:

The motor mount that I used parts from.

It’s a motor mount for electric boats, made by Ansmann Racing. By looking at the pictures, I could tell that it was a little too wide, even if removing the mounts on the sides. The integrated “wing mounts” could however be used with a little engineering. What I had to do was take a bent Scorpion chassis rail (that I was about to throw away, anyway), and cut two pieces of the same lenght as the mount, drill a few holes, and mount them at the sides of the rear rails on the Assault (using the existing holes in the rear Assault rails), making the rails wide enough to bolt the mount on them. Then I used some nylon spacers to mount the side plates. The side plates are now a little bit more outwards, but that is not a problem.

This is how the motor mount is bolted to the doubled chassis rails.

As I couldn’t find an Assault rollbar, and because the Advance rollbar (that I have) is too wide for the Assault body (The Advance is a frame rail buggy), I had to do some custom work. I used a standard Scorpion rollbar, mounted about 0.5cm further forward than the original Scorpion position, by drilling some new holes in the suspension support plate. The original Advance and Assault roll bars are both wider at the base that the Scorpion roll bar, and mounted further forward, to get the body in the right position. This mod made it possible to mount the roll bar in it’s normal position, and the Scorpion roll bar is narrow enough to fit inside the Assault body, thus overcoming the problem of not having an original Assault roll bar.

And here is a pic with the body on. I still have to cut the wing, though.

The next challenge was the rods that make up the rest of the cage. On the Assault the bars that goes from underneath the top of the roll bar and extends back to the side plates, are straight. But as I have mounted a mono shock unit, straight bars will interfere with the mono shock units action. So the solution was to make some bent rods for the cage. I bought some 6mm alu rods, bent and cut them, and drilled some holes to mount them. I think the result is pretty nice.

The custom made cage.

The next thing I did was drawing up the chassis plate that holds the battery (mounted lenghtwise, and as far forward as possible, for better balance), and a radio gear plate, and sent the designs off to Fibre-Lyte in England to be cut in CSC, a carbon/glass composite. I used some RC10 battery cups to mount the battery.

The CSC plates I designed and had Fibre-Lyte cut for me.

Here I have mounted the CSC plates, and have started to mount the electrics. I’m using black RC10 battery cups, and the battery sits nice and tight a quarter under the radio plate, but it’s still possible to remove it quite easily. The body and wing are still not painted. The wing mount is the plastic option part for the re-released Scorpion, but this I later changed for the original Turbo Scorpion aluminum part.

In the next pictures I have wired and mounted the electronics. The receiver is a black and gold Tekin Terx and the ESC is a black and gold Magic K-80 Power Mosfet II. The steering servo is a black and gold Futaba S3003.

In these last pics, the body and wing are painted. I still need to add the pin-stripes, with white Kyosho micron line tape, to cover all the rough edges between the colors, as well as apply the decals. I still suck at painting. No matter how much attention I pay to the masking, the paint always seems to bleed and produce rough edges. Luckily on this build the micron line tape will cover that. I wanted the yellow to be a bit darker than the standard Assault color, but the Tamiya Camel Yellow came out maybe a bit to dark for my liking. We’ll see how it looks with the micron tape and the decals, it might be good enough.

Here is a list of parts used:

-Kyosho gold front shocks
-Kyosho gold rear shock
-Kyosho Advance/Assault transmission
-Kyosho Advance/Assault wheels and tires
-Kyosho re-release Beetle/Tomahawk front shock tower spacers
-Kyosho Turbo Scorpion aluminum wing mount
-Kyosho/Mabuchi Torque motor
-Associated #6334 black battery cups
-Ansmann Racing motor mount
-CRP wide front axle
-Custom made cage
-Custom made front shock tower stiffener
-Custom made rear stabilizer/sway bar
-Dirt Burners! mono shock unit (replica)
-Fibre-Lyte made battery plate (my custom design)
-Fibre-Lyte made radio plate (my custom design)
-Futaba servo
-Magic K-80 Power Mosfet II ESC
-MST turnbuckles for the mono shock linkage
-Novak Mod.1 pinion for 5mm axle
-Ofna Racing 5mm to 3mm axle adapter
-Pargu long front shock towers
-Tekin TERX receiver

This is not a web-shop

This is not a web-shop, and beside what’s listed under the “FOR SALE” tab in the menu, nothing presented here is for sale, so please don’t ask. If I have anything I would like to sell, I’ll post it in the “FOR SALE” section.

About TomEG 56 Articles
I have been into RC cars since the beginning of the 80's, but have really never been much of a racer. I competed in some local races and some "Tamiya Cups", and actually came 6th in the Tamiya Cup Norwegian Nationals in 1987. My main interest has always been building and modifying, and that's where I still am today. Through the years I have been able to build a solid network of contacts around the world, consisting of both former and current members of the industry, as well as quite a few of the former top drivers. I have a genuine interest for the history of the 1/10 scale off-road buggies from the 80's.

4 Comments

    • Hi Chad. Still not 100% finished, but this is for the shelf, and will not be run. Maybe a short run on a dry and clean place once in the future.

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