1/8 Electric Taken to the Text Level!

[SpEEdyBL]

My patience waiting for companies to design an electric buggy from the ground up and done correctly had run out. Therefore it was time for me to go to the drawing board and attempt to do it myself. The compatibility a single brick pack or dual battery packs, a centerline driveline, centerline weight distribution and low CG all seemed simultaneously possible and favorable, yet did not seem to exist. So here is what I came up with, and it is a few steps ahead of both the Caster Fusion and Hyper 9e in terms of chassis layout.

It began with a Losi 8ight chassis, and me being a mechanical engineering student with access to the machine shop at school. I know the offset rear driveshaft makes it all that much more difficult to make completely centerline, but I’ve owned my 8ight as an electric for almost three years. I trust it, I know it inside and out – I could make it work. In short, after A LOT of thought, taking countless measurements with calipers, making a series of CAD models, drawings, and hours track mill time, here it finally is! (See attachments)

The first thing that had to happen was to put the front diff housing in the rear. This was not easy. The pivot braces that hold the a-arms are optimized for front suspension geometry and a front shock tower, which forced me to integrate the diff housing into the rear of the chassis… a few extra parts and some custom fitting, whatever… done.

As you can see, the center diff is moved as far forward as possible – the front outdrive nearly touches front diff housing. Keeping the wheelbase the same as stock, this leaves 214mm of space in the chassis for everything else. Dual battery packs of ROAR spec take up no more than 140mm, leaving enough room for a Tekin or Castle buggy motor on one side of the driveline and the rest of the electronics on the other side – even the big Mamba monster will fit with the receiver pushed off to the side. If one brick pack is used, everything else goes behind the motor. In the pictures are dual 40C 3000mAh 3s packs and a Tekno-Neu 1509 2.5Y/Mamba Max Pro esc.

Additional Design Features

Chassis: Made out of 3/16 inch thick 7075-T6 aluminum, countersunk .1100 inches to lower batteries by nearly a half inch, and then some due to the dual pack layout vs. a tall single pack. Right now, packs are just Velcro-ed to the chassis (works really well for slim packs weighing less than 12 ounces), but I will eventually make brackets that hold battery straps.

Motor plate: easy slide in allowing the motor screws to only need partial adjusting upon changing motors and pinion gears. Since the chassis is 3/16” thick, the Kyosho 46 tooth spur fits with ease. The motor plate also doubles as a servo holder and the servo mounts to it the same way the servo mounts in the Losi xxx-4 or in many other 1/10 scale vehicles.

Center drive shaft: Just an oversized aluminum rod poorly turned down on the lathe with holes to fit the CVD coupling and a press-fit pin for the dog bone end. It works.
Shock towers: Similar hole positions, but half inch lower shock mounts in the rear, and will be a quarter inch lower in the front (haven’t made the front shock tower to match the rear yet). I found that lowering the shock towers by this amount works just fine for all off road conditions through experience with using modded L8ight Model shock towers on the 8ight beforehand.

The end result?

A setup is approximately 6.6lb, and drops to 6.1lb with dual 40c 1800 mAh 3s packs – more than enough juice for 10 minute mains. I’ve only done one race night (I guess I can say I won) and some bashing in the street, but after this, the buggy’s handling is so much more precise with a lot more grip and no more lifting wheels in corners.

I am hoping after this, and the word is spread, companies will start catching on to finally do 1/8 electric the way it should be done. If by chance, you are an interested representative of a company, a PM would be highly appreciated.

I will add updates as this project continues.